Method of manufacturing an optoelectronic device with integration of quantum dots, esp. in green energy applications, and system therefor

Abstract

This invention concerns a remarkable method of an integration of Quantum Dots in optoelectronic devices in for including embedding quantum dots (metallic, inorganic or colloidal) within different layers of the multilayer structure of the emerging thin film optoelectronic devices such as Organic Photovoltaics - OPVs, Perovskite Photovoltaics - PPVs, Organic Light Emitting Diodes - OLEDs to achieve higher performance and subsequently deploying these improved flexible and lightweight devices in Agriculture notably Greenhouses, Open Field Cultivations, Breeding, as well as notably Glass Buildings, UV Health-care protection. This invention promotes the enhancement of power conversion efficiency of semitransparent OPV panels and desirable properties of optoelectronic devices as well as the enhancement of crop production more than 30%. This phenomenon is attributed to a combination of factors: the shading effect generated by OPV panels and an even bigger enhancement as a result of the incorporation of quantum dots within a nanolayer of the multilayer structure of an optoelectronic device. These quantum dots, acting as additives in solutions, are printed onto a substrate and have the ability to achieve optical engineering and optical tuning by controlling the solar spectrum that penetrates through optoelectronic devices, thus the manipulation of absorption across a range of wavelengths, including far UV, UV, and even less beneficial visible wavelengths, is realized. Consequently, these wavelengths are efficiently converted into more advantageous blue and red wavelengths for agricultural applications, or even in any preferable wavelength of the visible spectrum in applications such as glass buildings.

Description

[0001] Method of manufacturing an Optoelectronic Device with Integration of Quantum Dots, esp. in Green Energy Applications, and system therefor

[0002] DESCRIPTION

[0003] Technical field of the invention

[0004] The present invention relates to a method for Quantum Dots production and their integration on a multilayer structure of optoelectronic devices, esp. in a variety of applications notably in the field of energy production from renewable sources in greenhouses and open field cultivations, glass buildings and architectural structure, health, tourism, transportation.

[0005] Background of the invention

[0006] Organic photovoltaics -referred to hereinafter as OPVs- have emerged as a promising alternative to traditional inorganic solar cells (Si based- 1stgeneration, and thin film based-2ndgeneration) owing to their semitransparency, lightweight, flexibility, low cost in production, easy installation and recyclability. The power conversion efficiency -referred to hereinafter as PCE- of OPV Panels is still lower than that of inorganic solar cells, even though the new organic semiconducting materials provide lab efficiencies of almost 20%. Nevertheless, there is a promising upward trend in PCE for OPVs as they represent the 3rdgeneration of photovoltaics PVs, indicating a potential improvement in the upcoming years, while conventional PVs have already reached their peak in power conversion efficiency. To improve the performance of OPVs, researchers have explored various strategies, such as incorporating different types of organic and inorganic materials, optimizing the device architecture, and improving the charge transport properties of the active layer contained therein.

[0007] As solar power gains global popularity, recent advancements have introduced organic solar cells, replacing traditional thin-film and PV technology. They constitute lightweight, recyclable, and flexible cells offering a higher efficiency in various types of locations due to their easy installation and adaptability to different surfaces.

[0008] In the specific case of agrivoltaics where solar modules are placed strategically above crops to provide shade and generate power, semitransparent organic solar OPV panels emerge as a game-changer. Organic cells in comparison with conventional solar cells overcome many challenges by allowing the full area to be used for crop growth and facilitating the use of standard machinery. The flexibility of organic modules ensures a balance between shade and sunlight, optimizing agricultural productivity. With benefits such as increased energy savings, healthier crop yields, and resilience against damage, organic solar technology is promising to revolutionize agrivoltaics and find an increased adoption among farmers seeking sustainable and efficient solutions.

[0009] On the other hand, greenhouse and open field cultivations have become increasingly important for sustainable food production, especially in regions with adverse weather conditions. However, the growth and yield of crops in greenhouses or open field cultivations are often limited by the low light intensity and narrow spectrum of artificial lighting. To overcome this challenge, researchers have investigated the use of different types of light sources, such as LEDs and fluorescent lamps, as well as the use of light filters and coatings.

[0010] Besides, there has been recently a growing interest in incorporating photovoltaic technologies into building structures to enhance sustainability. The focus extends beyond traditional rooftop solar panels, as researchers explore innovative ways to integrate photovoltaics into various components of a building. One notable avenue of exploration involves embedding photovoltaics within glass windows or retrofitted in glass surfaces, thereby utilizing the entire building surface for energy generation. But because of the opacity, the size and the weight of silicon-based photovoltaics, PVs cannot be embedded within glass windows. This approach not only would maximize energy production, but it would also address health and furniture protection concerns associated with ultraviolet UV radiation. To mitigate the impact of UV radiation on human health and prevent skin-related issues, researchers are developing materials that can be either integrated or incorporated into glass windows. This dual-purpose strategy not only transforms buildings into energy generators but also promotes the well-being of people.

[0011] To achieve these goals, alternative technologies such as organic photovoltaics OPVs and thin- film technologies are being considered as viable options for integration into glass surfaces, offering a promising step towards a more sustainable and health-conscious future.

[0012] Quantum dots -referred to hereinafter as QDs- have attracted significant attention in recent years due to their unique optical properties, including strong light absorption and emission in the visible and near-infrared regions, as well as high photoluminescence quantum yield and stability. QDs have been used in various applications, such as bioimaging, sensing, and catalysis. However, their potential application in OPVs in greenhouse and open field cultivation, as well as in OPVs in glass buildings, in Organic LEDs -referred to as OLEDs- has not been explored extensively yet. These QDs are to be understood herein in this application as particles that are so small that their electronic energy levels become discrete — similar to those of atoms. This is known as the quantum size effect or quantum confinement, which results in a) Size-dependent energy levels and b) Discrete absorption and emission spectra. At these sizes, plasmonic behavior disappears, and fluorescence with long lifetimes (nanoseconds to microseconds) appears.

[0013] There is thus a need for an improved method for enhancing the performance of optoelectronic devices, notably in greenhouse and open field cultivation, buildings, by incorporating QDs into the multilayer structure of the devices, e.g. OPVs, Perovskite Photovoltaics -referred to as PPVs, Organic Light Emitting Diodes OLEDs.

[0014] Prior art

[0015] Previous studies have incorporated additional elements like metallic gratings or plasmonic nanoparticles in combination with QDs. However, a novel approach that involves integrating QDs within the electron transport layer of OPVs or in more than one layers of the multilayer structure of optoelectronic devices, is a strategy not previously explored. Plasmonic nanoparticles have been employed inside optoelectronic devices, such as in the photoactive or electron transport layer of an OPV device, but this was done independently, without utilization of any kind of quantum dots.

[0016] In US9318648B2 a method to produce artificial light for plant cultivation is disclosed. However, this document neither addresses nor discloses utilization of OPV technology in combination with said Quantum Dots.

[0017] In this respect US9905790B2 discloses a method to use quantum dots as an active layer of an optoelectronic device.

[0018] Aim of the invention

[0019] This invention aims to address the above-mentioned need by providing a novel approach for a simultaneous enhancement of desirable properties OPVs’ efficiency, such as UV absorption, emission at desirable wavelengths for specific applications, of optoelectronic devices.

[0020] An object of the invention is also to promote certain applications with the optimization thereof notably including crop yield in greenhouses and open field cultivations using Quantum Dots QDs.

[0021] Summary of the invention

[0022] There is thus provided according to the invention, a method as defined in claim 1 below for the fabrication of an optoelectronic device with a multi-layer structure provided with additives comprising the following steps:

[0023] - depositing a nanolayer or nanocoating of electron transport material as an intermediate layer, on a substrate, esp. wherein said nanolayer deposition coating consists of a layer or film with nanometer thickness formed by the deposition of material, - depositing an active nanolayer solution on top of the said electron transport layer,

[0024] - depositing a hole transport nanolayer solution on top of the active layer,

[0025] - depositing a layer of anode material, on top of the hole transport layer; wherein the method is remarkable in that said additives are made of small-sized nanoparticles of the type referred to as quantum dots QD, wherein said quantum dots are sized at a few nanometers, typically 2-10 nm, that are incorporated in at least one of above-mentioned layers, particularly in one of said intermediate layers, more particularly in said electron transport material layer; a wet chemical synthesis is further applied through which said quantum dots are synthesized with a targeted size and shape. Thereafter, the synthesized quantum dots QD are dispersed into said solution(s), which is resp. are mixed, wherein said quantum dots QD remain as individual additives without getting mutually agglomerated during said mixing, thereby forming a Quantum Dot QD enhanced Solution, which constitutes the original solution that is getting modified by the addition of Quantum Dot QDs in order to enhance the operation performance of the optoelectronic device.

[0026] Each said nanolayer solution is dried after said mixing through intermediate drying between layer depositions, thereby constituting a multi-layer structure of said optoelectronic device.

[0027] Said multi-layer structure thus reinforced with said Quantum Dots QDs generates a power enhanced optoelectronic device yielding an improved performance of an OPV photovoltaic device due to the addition of said Quantum Dots QDs in one of the intermediate layers of the OPV, wherein said power-enhanced optoelectronic device corresponds to an improved operation of the optoelectronic device due to the addition of QDs in one of its layers. In an OPV, this results in an increased Power Conversion Efficiency PCE.

[0028] According to the method of the invention, it is thus started from Synthesizing a Quantum Dot- Enhanced Solution, to form an Optoelectronic devices intermediate Layer. In KR20160052871 , a solution of gold nanoclusters is deposited via spin coating onto a zinc oxide layer that was previously deposited separately on a glass substrate. In contrast, the invention refers to the incorporation of a QD solution into a separate material solution, such as electron transport material, which is then deposited to form a nanolayer. The mixing of QDs prior to deposition introduces a functional differentiation in the electronic behavior of the resulting nanolayer. Furthermore, the device in KR20160052871 is a solar cell, but no encapsulation process is mentioned to protect it from environmental factors. The absence of encapsulation significantly reduces the lifetime of the device. In contrast, a QD solution of the invention is incorporated into a separate material solution, such as electron transport material, and then deposited to form a nanolayer. Said method particularly comprises sequentially depositing onto the said substrate the multiple layers that are formed by drying the respective fluids of said solutions.

[0029] Regarding said QDs, the Bohr radius of an exciton is the average distance between the electron and the hole in a bulk semiconductor. Exciton Bohr radius is not defined for gold because it is a metal, not a semiconductor, so the concept of an exciton Bohr radius doesn’t directly apply in the same way it does for semiconductors like CdSe or GaAs. The term “QD or quantum dot” is justified by the fact that noble metal particles like gold, when sized at a few nanometers (typically 2-10 nm), are so small that their electronic energy levels become discrete, similar to those of atoms, i.e. the quantum size effect or quantum confinement. At these sizes, plasmonic behavior disappears, and fluorescence with long lifetimes of the order of nanoseconds to microseconds appears. In the case of the invention, the metallic particles have a metallic core with a diameter of 1 ,5 to 3 nm and are surrounded by a protein-based stabilizing agent. Therefore, a bandgap is formed between the valence band and the conduction band. This approach leverages the unique electronic structure of the QDs to enhance the spectral absorption of the device according to the invention.

[0030] In KR20160052871 , a solution of gold nanoclusters is deposited via spin coating onto a zinc oxide layer that was previously deposited separately on a glass substrate. In contrast, the invention refers to the incorporation of a QD solution into a separate material solution, such as an electron transport material, which is then deposited to form a nanolayer. The mixing of QDs prior to deposition introduces a functional differentiation in the electronic behavior of the resulting nanolayer. In contrast, a QD solution is incorporated into a separate material solution, such as electron transport material, and then deposited to form a nanolayer.

[0031] US2022 / 0328781A1 discloses a simple mixture of ZnO nanoparticles with Au and S that is used for a hydrothermal reaction. There is no mention of gold QDs. Moreover, a separate QD nanolayer is used in Figure 3, and on top of it a ZnO@ZnS-Au nanolayer. In contrast, in the invention above, a QD solution is incorporated into a separate material solution, especially in said electron transport material, and then deposited to form a nanolayer, which is different from the invention, which is also the case for the intermediate drying between layer depositions.

[0032] The term "nanolayer deposition," resp. "nanolayer coating," refers to a layer (film) with nanometer thickness formed by the deposition of material.

[0033] The expression " dispersed within a material solution" means that the quantum dots are dispersed in the mentioned solution and remain as individual QDs without forming agglomerates during mixing. The expression "QD-enhanced pattern" refers to the improved performance of an OPV photovoltaic device due to the addition of QDs in one of the intermediate layers of the OPV.

[0034] The phrase "power-enhanced optoelectronic device" refers to the improved operation of the optoelectronic device due to the addition of QDs in one of its layers; e.g. in an OPV, this results in an increased Power Conversion Efficiency PCE.

[0035] The expression "QD-enhanced solution" means that the original solution has been modified by the addition of QDs in order to enhance the operation performance of the optoelectronic device.

[0036] According to a particular embodiment of the method of the invention, said intermediate layer is formed as a thin film, particularly substantially uniformly, by synthesizing the Quantum Dot- Enhanced Solution, wherein said electron transport material layer is deposited as an intermediate layer on said substrate, which consists of a plastic substrate that is coated esp. with an indium tin oxide ITO, thereby forming a uniform thin film; and / or said active layer solution is deposited on said electron transport layer film as a substantially uniform thin film; and / or said hole transport layer solution is deposited on said active layer as a substantially uniform thin film; and / or said anode material layer, esp. silver or gold, is deposited on said hole transport layer, wherein said additives are incorporated as quantum dots at least in said intermediate layer; wherein said Quantum Dot enhanced Solution produces a photoactive layer, an emissive layer and / or the electron or hole transport layer of the optoelectronic device as well.

[0037] Although individual components such as metal oxides notably ITO and plastic substrates may occur in the field of organic electronics, it is not referred to herein to a mere aggregation of known techniques but to a specific combination and layering of materials and processes aimed at improving device stability, compatibility with R2R printing, and enhanced functionality (electrical / optical). The incorporation of a QD solution into a metal oxide solution and its use as an electron transport layer in fully printed flexible optoelectronic devices with improved efficiency does not obviously arise from KR20160052871.

[0038] According to a more particular embodiment of the method of the invention, said respective fluids comprise solvents that are compatible with each other, thereby preventing a previously deposited / printed layer from being damaged by a solvent of a subsequently deposited or printed layer. There is specified herewith the careful selection of solvents to ensure compatibility between successive layers to avoid interlayer diffusion, which is not disclosed in KR20160052871. It is thus referred on the one hand to the compatibility of the solvents used for the deposition and formation of each distinct nanolayer, and on the other hand to the intermediate drying of the successively deposited nanolayers. Furthermore, it highlights that all nanolayers have been deposited using printing techniques, such as slot-die, blade coating, screen printing, gravure, which are compatible with Roll-to-Roll (R2R) printing and suitable for large-scale production. In addition, a specific selection of solvents is proposed that prevents the intermixing of materials between successive layers, thereby avoiding inter-diffusion between the functional layers of the optoelectronic device. All of the above constitute a technique and process that is neither disclosed in KR20160052871.

[0039] According to a still more particular embodiment of the method of the invention, said multi-layer structure of said optoelectronic device is encapsulated, esp. through laminated barrier films using multilayer flexible membranes that include inorganic barrier layers and moisture absorbers thereby isolating said multi-layer structure for protecting said optoelectronic device. This is thus intended for the protection of the optoelectronic device from environmental factors that negatively affect its operation and lifespan, such as moisture and oxygen. Encapsulation is a critical factor for the exploitation of OPVs as it ensures operational stability during long-time use. The combination of QDs and encapsulation constitutes an undisclosed functional configuration with improved stability and performance characteristics. No encapsulation process is mentioned to protect it from environmental factors in KR20160052871. Furthermore, the device therein is a solar cell, but no encapsulation process is mentioned to protect it from environmental factors. The absence of encapsulation significantly reduces the lifetime of the device.

[0040] According to an even more particular embodiment of the method of the invention, the electron transport layer is made with a blend, which is quantum dot QD enhanced, notably consisting of a quantum dot QD enhanced metal oxide, and wherein a blend of SnO, SnO2, AZO or MoO nanoparticles and gold, silver or other metallic quantum dots QD is incorporated in said quantum dot QD enhanced metal oxide; it is formed by

[0041] (i) blending the metal oxide nanoparticles solution contained in a first solvent comprising water or alcohol with the metallic quantum dots QD contained in a second solvent that is compatible with the said first solvent,

[0042] (ii) mild stirring through which a uniform blend is created, after drying same and depositing the blend, thereby generating the formation of a homogeneous layer.

[0043] Again, although individual components such as the abovementioned metal oxides SnO, SnO2, AZO, MoO are in the field of organic electronics, it is not referred to herein to a mere aggregation of known techniques but Instead, they concern a specific combination and layering of materials and processes aimed at improving device stability, compatibility with Roll-to-Roll (R2R) printing, and enhanced functionality (electrical / optical). The blending of a QD solution with a metal oxide solution and its use for forming an electron transport nanolayer in fully printed flexible optoelectronic devices with enhanced performance does not arise in an obvious manner from KR20160052871.

[0044] According to a yet more particular embodiment of the method of the invention, any of said -or even each- layer of the multiple layer structure of said optoelectronic device is fabricated by slotdie, or screen printing; or possibly by blade coating, inject printing, gravure, flexography.

[0045] So, all the layers are deposited via printing processes, such as slot-die, blade coating, screen printing, gravure, compatible with roll-to-roll printing, in contrast with KR20160052871 wherein it is not the case.

[0046] According to a specific embodiment of the fabrication method of the invention of an optoelectronic device with said multi-layer structure enhanced with quantum dots QD as additives, it is made with the following components and comprises the following steps:

[0047] (a) starting from the substrate that is a flexible substrate, which is selected notably from an ITO- coated plastic PET or PEN substrate;

[0048] (b) the electron transport layer solution consists of a metal oxide that is blended with quantum dots, particularly gold quantum dots that are tailored with specific sizes and concentrations;

[0049] (c) the active layer that is formed by depositing a solution of a conjugated polymer or small molecule or micromolecule, notably P3HT polymer and fullerenes like PCBM, esp. by applying a Roll to Roll (R2R) compatible printing technique, particularly slot-die coating;

[0050] (d) the hole transport interfacial layer comprises organic materials like PEDOT:PSS, and it is deposited on the active layer facilitating hole transport;

[0051] (e) an Anode Layer is made of a metal or metal oxide material, esp. aluminum or silver.

[0052] Still again, although individual components such as the abovementioned metal oxides and plastic substrates occur in the field of organic electronics, it is not referred to herewith to a mere compilation of known techniques, but to a specific combination and layering of selected materials and processes aimed at improving device stability, compatibility with R2R printing, and enhanced functionality (electrical / optical). The incorporation of a QD solution into a selected metal oxide solution and its use as an electron transport layer in fully printed flexible optoelectronic devices with improved efficiency does not obviously arise from KR2016005287.

[0053] According to a more specific embodiment of the fabrication method of the invention, an Organic photovoltaic panel referred to as OPV is selected as the optoelectronic device, wherein metallic quantum dots QD are embedded, thereby generating an increased power conversion efficiency corresponding to an enhanced power output for said optoelectronic device by an upgrade up to 20% percentage, esp. in comparison with a reference OPV without quantum dots. According to a still more specific embodiment of the fabrication method of the invention, for synthesizing gold quantum dots, it comprises the following steps:

[0054] (a) Preparing a solution of a gold precursor, such as HAuCk in the appropriate concentration inside a suitable solvent, including water or ethanol, wherein the said solution is then mixed with a stabilizing agent such as Bovine Serum Albumin BSA solution and the gold precursor solution is formed, wherein Controlled stirring conditions are implemented leading to the reduction of Au3+to Au1+of most of the gold atoms, resulting from reducing and stabilizing activities of BSA protein;

[0055] (b) a Reduction Reaction, wherein a reducing agent, such as sodium hydroxide, borohydride or citrate, is added to the gold precursor solution under controlled conditions of temperature, pH, stirring and reaction time, thereby facilitating the controlled formation of gold nanoparticles, during which reaction, gold atoms are reduced from Au1+to Au° to form clusters, wherein BSA acts as a reducing and stabilizing agent, contributing to controlling the size of BSA-Au quantum dots, wherein the addition of a base such as a hydroxide esp. NaOH raises the pH, enhancing the reducing capability of BSA, wherein the concentration of gold atoms increases progressively over time in accordance with the reaction duration, after which the gold precursor becomes depleted and undergoes reduction once the reducing agent is introduced;

[0056] (c) the size and shape of the gold nanoparticles are controlled by adjusting reaction parameters, including the concentration of the reducing agent, stirring, temperature and incubation time;

[0057] (d) thereafter, the synthesized gold quantum dots solution is purified through a process involving centrifugation, filtration and washing, removing any unreacted precursors or byproducts.

[0058] KR 20160052871A discloses a solution of gold nanoclusters that is deposited via spin coating onto a zinc oxide layer that was previously deposited separately on a glass substrate. In contrast, it is referred in the invention above to the incorporation of a QD solution into a separate material solution esp. electron transport material, which is then deposited to form a nanolayer, which is different from the invention.

[0059] According to an alternative embodiment of the fabrication method of the invention, the quantum dots’ QD solution is made colloidal with desired size, design and QD characteristics, and synthesized by means of a wet chemical process, in particular by co-precipitation. More particularly, said colloidal quantum dots are made of various sizes, esp. with hydrodynamic diameters of 4,8 nm, and / or to 5,6 nm in order to exhibit preferential features for a variety of applications. A colloidal quantum dots’ solution of desired QD size may thus be synthesized using a wet chemical process esp. a co-precipitation method. According to a further embodiment of the fabrication method of the invention, for synthesizing a quantum dot-enhanced solution for the intermediate layer of said optoelectronic device, it comprises the following steps:

[0060] (a) synthesis of the Quantum dots of specific sizes and shapes are synthesized using the above- mentioned wet chemical synthesis;

[0061] (b) preparation of the electron transport layer solution by dispersing the appropriate amount of the synthesized Quantum dots in the solution of an electron transport material, such as a metal oxide, and mild stirring afterwards;

[0062] (c) deposition of the electron transport layer solution onto a plastic substrate using a Roll-to-Roll compatible printing technique such as slot-die or blade coating, thus generating the formation of a uniform thin film;

[0063] (d) annealing the deposited layer at optimized temperature and duration conditions, thereby enhancing the properties of the electron transport material with embedded Quantum dots.

[0064] According to another embodiment of the fabrication method of the invention, metallic quantum dots are introduced inside the intermediate layer of said optoelectronic device thereby generating the absorption of Far-LIV and UV-light and its conversion to visible light wavelengths A.

[0065] These QD particles are so small that their electronic energy levels become discrete, similar to those of atoms.

[0066] Said Optoelectronic device is manufactured with a method as defined above, wherein said optoelectronic device is fully printed. It is fully printed in that all the individual layers of the multilayer structure of the respective optoelectronic device are deposited using printing techniques compatible with roll-to-roll printing, such as slot-die, blade coating, or screen printing. The attribute "fully printed" constitutes an essential technical feature that differentiates the abovementioned device according to the invention from conventional or partially printed devices, which are realized using alternative or incompatible technologies such as thermal evaporation, sputtering. The fully printed device introduces a technical innovation, enabling the implementation of optoelectronic devices with improved compatibility for mass production, reduced cost, and the use of flexible substrates. In contrast, document KR2016005287 discloses deposition techniques such as spin coating on glass and not on flexible substrates and there is no mention of fully printed optoelectronic devices. US2022 / 0328781A1 also uses deposition techniques such as spin coating on glass and thermal evaporation, again with no reference to fully printed optoelectronic devices. According to a remarkable embodiment of the fabrication method of the invention, the optical spectrum is tuned by controlling the size of synthesized quantum dots, thereby transforming UV or visible wavelengths to longer visible wavelengths, esp. wherein the QDs synthesis is modified by varying and tailor-made emission characteristics, thereby producing QDs, esp. tailored OPVs that integrate QDs of specific sizes meeting unique wavelength requirements. It is referred to herein to the emission and down-conversion characteristics of the QDs described below with reference to Figs. 8, 9, and 12, where the ability of QDs to emit light and to be used as downconversion materials to modify spectral response is discussed. According to the method, said transformation of wavelength is carried out as a conversion of UV, green and yellow wavelengths to red and blue wavelengths, which are transmitted through an OPV panel and are especially selected. While the photoluminescence of ultra-small noble metal clusters is a known design feature, the above applications of QDs with proper incorporation into solutions for forming device layers are not disclosed in KR2016005287. The aforementioned application of QDs through their tailored incorporation into a solution for the formation of nanolayers within the optoelectronic device is not described in KR2016005287. The exploitation of photoluminescence here does not simply reference a known property, but rather emphasizes the functional role of these nanoclusters within the device architecture.

[0067] The invention also relates to an optoelectronic device where it consists of an organic photovoltaic panel OPV, a Perovskite panel PPV or an Organic Light Emitting Diode OLED.

[0068] According to a particular embodiment of the device of the invention, said optoelectronic device consisting of an Organic photovoltaic panel, esp. semitransparent, is bifacial, in that it generates energy from both sides of the said panel, wherein one side is designed to capture maximum power and operates at a peak efficiency, whereas the opposite side contributes thereto as well by harnessing diffuse light, wherein this dual-sided panel means enhances the overall efficiency of the OPV system, maximizing energy production even including from indirect light sources.

[0069] This invention further relates to an optoelectronic system for operating a device as set out above wherein said optoelectronic device is provided with a tilting system by means whereof light transmittance is controlled completely regarding climatic conditions and season, wherein the angle and tilt of the panels are adjusted, thereby generating a dynamic tracking mechanism by means whereof enhanced light is absorbed and utilized, thereby increasing the overall energy efficiency.

[0070] According to an outstanding embodiment of the system of the invention, there is provided an Optoelectronic system for operating a device wherein the application of OPV consists of said tilting system in open field cultivation, and Greenhouse, esp. of fruits and / or vegetables, wherein said integrated OPV system is arranged on a frame, notably metallic, wooden, or concrete, on top of said open field cultivation, for both energy generation as well as an enhanced crop yield.

[0071] This invention also relates to a use of said device resp. system as set out above, wherein a shading effect is generated by said enhanced optoelectronic device on its streamdownward radiated environment, esp. on plants, by means whereof the associated crop production is increased, esp. exceeding 30% and / or water consumption decreased resp., depending on reduced evapo-transpiration thereby improving growth conditions, with simultaneous efficient energy harvesting. The enhanced optoelectronic device may thus provide an efficient shading effect on plants that are located in the sunbath, generating an increased crop production potentially > 30% and in a decreased water consumption depending on reduced evapotranspiration resulting in optimal growth conditions, with simultaneous efficient energy harvesting.

[0072] This can be implemented in greenhouse applications by incorporating quantum dots into the multilayer structure of semitransparent OPVs. The present invention thus provides a method of Integration of Quantum Dots in optoelectronic devices for Performance Enhancement in Green Energy Applications providing an increased efficiency and operation of printed optoelectronic devices. In particular, Organic Photovoltaics-OPVs can have a potential performance enhancement by 20%, using metallic quantum dots to increase energy production in greenhouses and open field cultivations, and to increase crop yield and improve crop quality. The integration of OPVs into transparent greenhouse surfaces is not described in KR2016005287 and does not include parameters related to transparency, light transmission, and selective absorption, which are covered by the claims. This application foresees combined energy generation and plant growth functionality.

[0073] According to the invention, said method of incorporating Quantum Dots QDs into a multilayer structure of an optoelectronic device is further proposed to subsequently place the enhanced device, such as an OPV, PPV or OLED, for a desired application in a Greenhouse or Open Field cultivation, as well as Glass Buildings and architectural structures, UV Health-care protection, tourism, transportation, food processing and packaging.

[0074] According to an additional embodiment of the invention, there is provided a further use of said device resp. system as well as with a method as defined above, wherein said optoelectronic device is enhanced for carrying out specific applications comprising Agriculture, notably Greenhouses, Open Field Cultivations, Breeding, esp. wherein said optoelectronic device OPV comprising PPV, OLEDs is integrated in structures for Greenhouses, Open Field Cultivations and Breeding for the agricultural applications; as well as Glass Buildings, tourism, transportation, food processing and packaging.

[0075] According to a useful embodiment of the invention, there is provided a still further use of said device or system for an installation wherein said optoelectronic device is integrated at the greenhouse metallic structure, esp. by means of their fixation into aluminum frames, in particular aluminum beams of tailored dimensions, that are positioned strategically by means whereof said OPV panels are stabilized uniformly esp. across a greenhouse roof, above an open field cultivation, or above a corral. The integration of OPVs into transparent greenhouse surfaces is not described in KR2016005287 and does not include parameters related to transparency, light transmission, and selective absorption, which are covered by the invention. This application foresees combined energy generation and plant growth functionality.

[0076] According to another embodiment of the invention, there is provided the use of said device or system wherein said enhanced optoelectronic device, resp. system is integrated in a glass building, or wherein said enhanced optoelectronic device is integrated in a glass building either by applying a retrofitted method onto an already existing structure, or by integrating said enhanced optoelectronic device, which is embedded within double-glazed windows as an integral component of said Glass Buildings.

[0077] An overview of the several applications provided with the invention is summarized below.

[0078] The OPVs and PPVs comprise a tilting system overall which is able to control light transmittance from 20% - 90%. Adjusting the angle and tilt of the OPV panels provides a dynamic tracking mechanism which allows an enhanced light absorption and utilization, thereby increasing the overall energy efficiency of the system.

[0079] The enhanced optoelectronic device provides an efficient shading effect on plants that are located in the sunbath, generating an increased crop production potentially exceeding 30% and in a decreased water consumption depending on reduced evapotranspiration resulting in optimal growth conditions, with simultaneous efficient energy harvesting.

[0080] It includes enhanced OPVs with metallic quantum dots and their application in energy-efficient greenhouses and open field cultivations which is analyzed below.

[0081] In first instance, the particular application of OPVs, PPVs and OLEDs in Greenhouses and Open Field cultivation comprises the following stages: a) Optical engineering to enhance red and blue regions of the visible spectrum boosting cultivation growth. b) Synthesis of metallic Quantum Dots Solution by applying a wet chemical technique, such as the Co-Precipitation method, which involves the chemical preparation of metallic quantum dots, notably Gold Quantum Dots. c) Purification of metallic Quantum Dots Solution notably Gold Quantum Dots by centrifugation to isolate and segregate common nanoparticles from the quantum dots, ensuring the purity of the quantum dot sample. d) Size Distribution Measurements of Quantum Dots which can be performed by Dynamic Light Scattering Spectroscopy (DLS), offering precise insights into the size variation within the quantum dot solution population. e) Embodiment of Quantum Dots into the Solution of the material to be deposited to form a specific layer of the optoelectronic device multilayer structure, by incorporating the appropriate concentration of quantum dots inside the solution. f) Fabrication of the layers of enhanced OPV, OLED or PPV by Roll to Roll (R2R) manufacturing i. Deposition of the Electron Transport Layer by a coating technique, such as Slot die Coating, or blade Coating Technique; ii. Deposition of Photoactive or Emissive Layer by a coating technique, such as Slot die Coating or blade Coating Technique, (esp. R2R compatible); iii. Deposition of Hole Transport Layer by a coating technique, such as Slot die Coating. iv. Deposition of Metallic Electrode by a coating or printing technique, such as Screen Printing or Slot Die Coating; g) Encapsulation of the Enhanced OPV, PPV or OLED modules to ensure the effective protection of modules from various from external environmental factors, including moisture, oxygen, UV radiation, and contaminants, which can degrade their performance and reduce device’s operational lifetime. h) Integration and connection of OPVs, PPVs or OLEDs with QDs and enhanced performance at about 20%, in Plastic or Glass Greenhouses and / or in Open Field cultivations, in order to increase the agricultural output.

[0082] According to a preferential embodiment of the method of the invention, an enhanced optoelectronic device is integrated in glass buildings, which involves inhibition of health risks and furniture corrosion with simultaneous efficient energy harvesting.

[0083] In addition, enhanced optoelectronic devices are integrated in glass buildings comprising two distinguished ways, wherein the first one is the retrofitted method which can be applied onto already existing structures, while the second one is the integration of enhanced optoelectronic device embedded within double-glazed windows as an integral component.

[0084] Secondly, the Application of enhanced OPVs on glass buildings: a) Optical engineering to enhance the visible spectrum, protecting health and reducing the deterioration of furniture from UV radiation; b) The experimental parts are common with the application in Greenhouses and Open Field cultivation; c) Integration and connection of OPVs, OLEDs, PPVs in the intermediate of glass windows or retrofitted on the surface of the glass.

[0085] According to another preferential embodiment of the method of the invention, it comprises sequentially depositing onto the substrate, respective fluids that are dried to form the multiple layers, wherein the respective fluids comprise solvents that are compatible with each other so that a solvent of a subsequently deposited or printed layer does not damage a previously deposited / printed layer. As a result, the blend with quantum dot can be enhanced used for the fabrication of high- performance optoelectronic devices.

[0086] According to a preferential embodiment of the method of the invention, the electron transport layer of the OPV device comprise a blend such as a metal oxide enhanced with quantum dot.

[0087] According to an outstanding embodiment of the invention, there is proposed a method of optical engineering by introducing metallic quantum dots inside an intermediate layer of said OPV, PPV or OLED device for absorbing Far-LIV and UV-light and converting some to visible light wavelengths, so as to simultaneously improve the optoelectronic device performance, crop and energy production and eliminate any negative effect of UV radiation for a variety of applications.

[0088] According to a further developed embodiment of the invention, there is proposed a method of tuning the optical spectrum by controlling the size of synthesized quantum dots to efficiently transform UV or visible wavelengths to longer visible wavelengths. Therefore, by modifying properly the QDs synthesis, one can craft QDs with varying and tailor-made emission characteristics. This adaptability facilitates the creation of tailored OPVs that integrate QDs of specific sizes to meet the unique wavelength requirements that may be specified in accordance with diverse cultivations.

[0089] Through the QDs' confinement, the conversion of solar UV and FUV energy spectra, even the 500-600 nm energy spectra into beneficial Photosynthetically Active Radiation PAR is achieved in plants growth. This optical engineering by an appropriate tuning contributes to an augmented and tailored made crop yield, optimal lighting conditions, effective filtering of UV radiation. More particularly, the tuning of the optical spectrum comprises-the conversion of UV, green and yellow wavelengths to red and blue wavelengths, which are transmitted through an OPV panel; they are especially selected for their beneficial effects on plant growth and crop production due to the absorption of chlorophyll a and b at these spectral regions.

[0090] In summary, this invention provides a remarkable development for embedding quantum dots, notably metallic, inorganic or colloidal within different layers of the-multilayer structure of the emerging thin film optoelectronic devices, such as Organic Photovoltaics OPVs, Perovskite Photovoltaics PPVs, Organic Light Emitting Diodes OLEDs, to achieve higher performance; and subsequently deploying these improved flexible and lightweight devices in Agriculture, notably including Greenhouses, Open Field Cultivations, Breeding, as well as Glass Buildings, UV Health-care protection, tourism, transportation, food processing and packaging. This invention promotes the enhancement of power conversion efficiency of semitransparent OPV panels and desirable properties of optoelectronic devices as well as the enhancement of crop production up to more than 30%. This enhancement phenomenon is attributed to a combination of factors: the shading effect generated by OPV panels with an even bigger enhancement as an outstanding result of the incorporation of quantum dots within a nanolayer of the multilayer structure of an optoelectronic device. These quantum dots, acting as additives in solutions are printed onto a substrate and have the ability to achieve optical engineering with optical tuning by controlling the solar spectrum that penetrates through optoelectronic devices. The manipulation of absorption across a range of wavelengths, including far UV, UV, and even less beneficial visible wavelengths is thus realized. Consequently, these possibly less desirable wavelengths are efficiently converted into more advantageous blue and red wavelengths for agricultural applications, or even in any preferable wavelength of the visible spectrum in other applications such as glass buildings.

[0091] Brief description of the drawings

[0092] FIG. 1 is a lateral view of an embodiment of a flexible printed organic photovoltaic OPV Panel showing the penetration of a solar radiation therethrough and its bifacial format.

[0093] FIG. 2a is a schematic illustration of an external top view, wherein FIG. 2b is a perspective view according to the invention and FIG 2c an internal perspective top view respectively of a further embodiment of an OPV Panels array integrated in a greenhouse according to the present invention.

[0094] FIG. 3 is a schematic illustration of a roof of a greenhouse with an OPV Panel array, esp. wherein the interconnection of OPV panels in series for implementation under the roof is depicted in FIG. 3a, while FIG. 3b represents an integrated tilting system of OPV Panels by means whereof the amount of solar radiation that penetrates and reaches the surface of the plants is regulated. FIG. 4a depicts a schematic illustration of an inverted OPV device structure for a conventional classic OPV and FIG. 4b an OPV with quantum dots according to the invention respectively.

[0095] FIG. 5 is a graphic representation of the transmission spectrum of the organic photovoltaics OPV device printed with so-called quantum dots QDs as referred to according to the invention. FIG. 6 is a schematic illustration of a metallic quantum dots synthesis process in a method according to the invention.

[0096] FIG. 7 depicts a schematic illustration of a gold quantum dots structure for two individual cases according to the invention, where in the center the metallic core of said quantum dots is identified, with diameter of 1 ,5 nm in FIG. 7a and of 3,0 nm in FIG. 7b respectively, and around the stabilizing protein agent.

[0097] FIG. 8 is a graphic representation diagram of an example of size measurements of a colloidal quantum dot solution in the method according to the invention, utilizing the Dynamic Light Scattering process.

[0098] FIG. 9 is a graphic representation diagram, combining absorbance and transmission spectra of the quantum dot solution according to the invention.

[0099] FIG. 10 depicts a schematic illustration of a smart window with integrated OPV Panel according to the invention in FIG. 10a retrofitted or embedded and its intermediate structure in the exploded view of FIG. 10b.

[0100] FIG. 11 is a representation of a tilting OPV Panel system according to the invention in FIG. 11b integrated above an Open Field cultivation of grapes in FIG. 11a.

[0101] FIG. 12 depicts a diagram with the absorption of chlorophyll (a) and (b), along with a solar spectrum and a representative example of photoluminescence emission of Gold Quantum Dots according to the invention.

[0102] Detailed description

[0103] The present invention provides a method for fabricating enhanced emerging and flexible devices such as organic photovoltaics OPVs, perovskite photovoltaics PPVs and Organic Light Emitting Diodes OLEDs incorporating quantum dots QDs, either metallic, organic, inorganic, or colloidal, or combining QDs with plasmonic NPs nanoparticles to improve their performance. Additionally, there is implemented a method for synthesizing quantum dots and fabricating quantum dot- enhanced layers for an optoelectronic device, notably including an emissive, photoactive, and transport layer. Quantum dots referred to herein are to be understood as nanoparticles wherein it is to be considered that the Bohr radius of an exciton is the average distance between the electron and the hole in a bulk semiconductor. The term “QD or quantum dot” is founded by the fact that noble metal particles like gold, when sized at a few nanometers (typically 2-10 nm), are so small that their electronic energy levels become discrete, similar to those of atoms. This is known as the quantum size effect or quantum confinement, which results in: a) Sizedependent energy levels, b) Discrete absorption and emission spectra. At these sizes, plasmonic behavior disappears, and fluorescence with long lifetimes (nanoseconds to microseconds) appears. In the present case of the invention, the metallic particles have a metallic core with a diameter of 1 ,5 nm - 3 nm and are surrounded by a protein-based stabilizing agent with reference to Figure 7. As a result, a bandgap is formed between the valence band and the conduction band. This approach leverages the unique electronic structure of the QDs to enhance the spectral absorption of the device.

[0104] A standard process for synthesizing Quantum Dots QDs is outlined, wherein control over QDs absorption in far UV, UV and even visible wavelengths allows for their conversion into blue and red wavelengths. The particle size dictates the wavelength emitted from the QDs. By introducing modifications to the method and their size, it becomes possible to generate QDs with diverse wavelength emissions. This versatility facilitates the production of optoelectronics tailored to various cultivation requirements, incorporating QDs of suitable material and sizes to match specific wavelength needs. For instance, there is the ability to design QDs that have the outstandingly beneficial property to absorb unwanted wavelengths, such as in far UV to UV, and the 500-600 nm spectra region, and in a particular cultivation scenario, on the one hand, and that have the capacity to convert them into beneficial wavelengths, on the other hand, which enhances the precision of environmental control. This fine-tuning of QDs fosters an optimal growth environment for cultivation growth, leading to a potential increase in height and crop production by 30% or more, as well as the crop quality.

[0105] A representative example of this method involving enhanced OPVs with metallic quantum dots and their application in energy-efficient greenhouses and open field cultivations is analyzed below in a more extended way. The application of OPVs, PPVs and OLEDs in Greenhouses and Open Field cultivation is set out hereafter accordingly. The method encompasses the application of the metallic quantum dot-enhanced OPVs and / or OLED lighting systems in energy-efficient plastic and glass greenhouses, and in open field cultivations. These semitransparent OPV panels 101 as shown in FIG. 1 , allow the required amount of Photosynthetically Active Radiation of 400-700 nm designated as PAR to penetrate beyond. This spectrum is optimal for plant photosynthesis and supports various essential functions. The OPV panel 101 acts as a filter for solar radiation 102, allowing the penetration of PAR. The interconnected contacts 104 link all OPVs, creating a pathway to either batteries or the grid. Organic photovoltaics OPVs have the innovative capability of being bifacial, meaning they generate energy from both sides of the panel. One side is designed to capture maximum power and operates at peak efficiency 101A. Meanwhile, the opposite side 101 B, though less efficient, still contributes by harnessing diffuse light. This dual-sided approach enhances the overall efficiency of the OPV system, maximizing energy production even from indirect light sources. The application of OPV panels, PPV panels and OLED devices in greenhouses or in open field cultivations includes the following steps as detailed hereafter:

[0106] (a) an Installation step, wherein the OPVs, PPVs and OLED lighting systems enhanced by the embedded quantum dots QDs are installed in the greenhouse and / or on open field cultivations resp. to provide the required light intensity and spectrum for an optimized plant growth. FIG. 2a depicts a panoramic view of the greenhouse roof top with the integrated OPVs 105 interconnected electrically. OPV panels 105 are implemented on an aluminum frame attached to the greenhouse metallic structure 103.

[0107] FIG. 2b shows an elevational view of the greenhouse 103 and integrated OPV system with positive and negative terminals 106 for further connection to batteries or the grid. FIG. 2c depicts the internal view of the particular greenhouse roof top integrated OPV system. FIG. 3a is a schematic representation of the installation of the OPV panels in a greenhouse rooftop where OPVs are interconnected in series and installed on the greenhouse construction. For this installation, a tilting system may be integrated therein in order to control the amount of light radiation 102 that reaches the plant surface and optimize the interior environmental conditions, with reference to FIG. 3b, by modulating the orientation of the OPV panels 105, which are rotatably arranged in coordination therewith with a pivoting movement between a passing state in upright position A as represented, allowing a full passage of the incident radiation 102, and a blocking state in a closed, filtering position B not shown, that is substantially orthogonal to the open position A, which constitutes the most filtrating position for said incident radiation 102.

[0108] Another paradigm of the application of OPVs consists of a tilting system 123 in open field cultivation of various kinds of fruits, e.g. grapes or other cultivations as peers, peaches, apples, tomatoes, berries, kiwis. This paradigm is depicted in FIG. 11. Specifically, FIG. 11a illustrates an integrated OPV system 121 on a frame 122, notably metallic or also wooden or concrete, above an open field cultivation of grapes cultivation, for both energy generation and enhanced crop yield. An alternative variant of the previous application demonstrating a tilting OPV system 123 is displayed in FIG. 11b as shown by the arrows therein.

[0109] (b) a Parameter Adjustment step, wherein Parameters of the OLED lighting system, such as light intensity, spectrum and duration, are adjusted and optimized to ensure the growth and yield of various crops.

[0110] (c) the Monitoring step, wherein Monitoring of the lighting system's performance and crop growth is undertaken using sensors and feedback control systems. Fabrication of the layers of enhanced printed optoelectronics is implemented in a fabrication method of the above-mentioned optoelectronic devices OPVs, PPVs and OLEDs that includes the deposition of specific functional layers on a substrate 107, esp. in plastic, glass, to form a multilayer structure as shown in FIG. 4a. These layers are enhanced by embedding a quantum dot-dispersion into a particular material to be used as an intermediate layer of the optoelectronic device. The fabrication process comprises the following steps: i. Deposition of the Electron Transport Layer 108 by slot die coating or other R2R compatible coating technique; ii. Formation of Photoactive or Emissive Layer 109 by a R2R compatible coating technique, such as slot die Coating or blade Coating Technique; iii. Deposition of Hole Transport Layer 110 by a R2R compatible printing technique; iv. Deposition of Metallic Electrode 111 by a R2R compatible coating or printing technique, such as Screen Printing or Slot Die Coating.

[0111] A representative example of a Fabrication Method of OPV with inverted structure is shown in FIG. 4a as described below. It comprises the following steps:

[0112] (a) Preparation of an Active Layer Solution: a solution of photoactive layer material for the OPV, such as a conjugated polymer or small molecule, is prepared to form a donor: an acceptor blend system. This solution may become the active layer of the OPV device.

[0113] (b) Incorporation of a Substrate 107: the device includes a flexible or rigid substrate 107, such as ITO-coated plastic PET and PEN, other plastic or glass, in which the optoelectronic device is fabricated.

[0114] (c) Deposition of an Electron Transport Layer 108: a layer of electron transport material 108, such as zinc oxide ZnO or tin oxide SnO2, is deposited onto the substrate notably using R2R compatible printing techniques, such as slot-die or blade coating, inject and screen printing, spin coating, gravure, flexography, vacuum techniques. The substrate 107 is e.g. an indium tin oxide ITO coated plastic. The deposition results in a uniform thin film, serving as the electron transport layer.

[0115] (d) Deposition of an Active Layer 109: the active layer solution is deposited onto the electron transport layer film using e.g. R2R compatible printing techniques such as slot-die coating, inject and screen printing or blade coating, spin coating, gravure, flexography, vacuum techniques. This deposition forms a uniform thin film, comprising the active layer material 109.

[0116] (e) Deposition of a Hole Transport Layer 110: a solution of hole transport interfacial layer material, notably including PEDOT:PSS or P3HT is deposited on top of the above-mentioned active layer 109 notably using R2R compatible printing techniques, such as slot-die coating, inject and screen printing or blade coating or spin coating, gravure, flexography or vacuum techniques. This Hole Transport Layer HTL 110 formation enhances the hole transport properties of the device.

[0117] (f) Deposition of an Anode Layer 111 : a layer 111 of anode notably including metallic material, such as silver, gold, is deposited onto the hole transport layer 110, utilizing various coating and printed techniques, such as vacuum thermal evaporation, inject or screen printing, slot-die coating, to complete the said inverted OPV device structure shown in FIG. 4a.

[0118] (g) Encapsulation and contacts: encapsulation measures are taken to improve device stability and performance of OPV panels.

[0119] Additionally, suitable metallic wires are connected to form the electrical contacts 104 of the OPV panel 105.

[0120] A representative paradigm of an enhanced OPV with Quantum Dots is shown in FIG. 4b and set out hereafter. The fabrication process for enhanced OPVs with quantum dots, involves the same method of fabricating OPVs, as described above, yet with a specific modification of the Electron Transport Layer ETL 108 solution.

[0121] A paradigm of an enhanced OPV with quantum dots comprises the following components:

[0122] (a) a Substrate 107: the device notably includes a flexible substrate 107, such as an ITO-coated plastic PET or PEN substrate.

[0123] (b) an Electron Transport Layer 108 Solution: this solution consists of a metal oxide blended with quantum dots, such as gold quantum dots 112 of specific sizes and concentrations, as shown in as margin to enhance electron transport layer 108 properties.

[0124] (c) an Active Layer 109: the active layer is formed by depositing a solution of a conjugated polymer or small molecule such as P3HT polymer and fullerenes like PCBM, notably using a Roll to Roll (R2R) compatible printing technique, such as slot-die coating.

[0125] (d) a Hole Transport Interfacial Layer 110: this layer, comprising organic materials like PEDOT:PSS, is deposited on the active layer 109 to facilitate hole transport.

[0126] (e) an Anode Layer 111 : the multilayer device 113 includes an anode layer 111 made of a metal or metal oxide material, such as aluminum or silver.

[0127] The incorporation of quantum dots 112 into an OPV can have a potential increase in the power conversion efficiency of the photovoltaics device up to more than 20%.

[0128] Optical engineering, OPV transmission properties and irradiation requirements for plant growth, crop production and glass building applications is set out hereafter. FIG. 5 shows the transmission spectrum of a specific printed organic photovoltaic panel 105. The amount of solar radiation 102 that penetrates through the enhanced OPV panel was measured, for a specific printed OPV at about 40% for particular wavelengths as represented in FIG. 5. Although, by incorporating quantum dots 112 into the OPVs, there is first an increase in OPV convention efficiency and second a prospect of achieving greater transmission percentages, thereby potentially further increasing crop production.

[0129] On the other hand, plants absorb more efficiently at red and blue light regions of the solar spectrum. Therefore, to optimize plant growth, it is essential to consider the photosynthetically active radiation PAR range, which is the spectrum of light that plants use for photosynthesis. The PAR spectroscopic or wavelengths range generally falls between 400 and 700 nm. Within this spectrum range, there are specific wavelengths that plants utilize most efficiently as follows: Blue light (~ 400-500 nm): this range is crucial for promoting vegetative growth and is essential for photosynthesis. Blue light is particularly important for the early stages of plant development as taught by FIG. 12.

[0130] Red light (- 600-780 nm): red light is essential for flowering and fruiting stages. It is crucial for the overall growth and development of the plant as visible from FIG. 12.

[0131] Green and Yellow light (~ 500-600 nm): this spectroscopic range is a low photosynthetic activity range.

[0132] Based on the diagram presented in FIG. 5 regarding the transmittance of the OPV panel 105, a clear correlation emerges with the optimal wavelengths essential for promoting plant growth: the peak transmittance at almost 500-530 nm is favorable because it falls within the blue light range, which is beneficial for vegetative growth.

[0133] The second peak at around 740 nm corresponds to a transmittance higher than 40% and is within the red-light range, essential for flowering and fruiting stages.

[0134] Considering these factors, the OPV panel 105 appears to have a reasonably good transmittance range for supporting plant growth. It allows sufficient light in both the blue and red ranges, which are critical for different stages of plant development. Concluding, with the incorporation of Au QDs 112 into the OPV panel 105, it appears to emit more red light, a crucial factor for enhancing plant growth.

[0135] Moreover, through the application of optical engineering, there is the capability to regulate the spectrum penetrating from Organic Photovoltaics using quantum dots QDs 112. In agriculture, this technology helps to selectively filter out harmful UV and far UV rays, which are destructive for plant growth: it notably hinders photosynthesis and harm plant tissues. Additionally, the influence of beneficial blue and red light is enhanced by optimizing growth and productivity of plants. Simultaneously, the unnecessary green-yellow light can be converted into red light, optimizing the overall light spectrum for plant development.

[0136] The beneficial effect of red and blue wavelengths of solar spectrum for plant growth can be further observed by the absorption peaks of chlorophyll (a) and (b) shown in FIG. 12. In specific, chlorophyll (a), which is the primary pigment of photosynthesis, absorbs at around 420 nm and 660 nm. Chlorophyll (b) is a supplementary pigment of photosynthesis and expands the range of wavelengths that can be utilized for solar light harvesting. Its absorption peaks are at around 453 nm and 643 nm as visible in FIG. 12.

[0137] To improve the light capturing of chlorophyll pigments, optical tuning can be performed. This tuning includes the control of absorption of Far UV and UV wavelengths by quantum dots and its conversion into preferable visible light, such as red and blue light. Furthermore, the undesirable wavelengths like green light can be also converted into beneficial wavelengths, such as red light. An indicating example of the above can be seen in FIG. 12 where Ultraviolet radiation is converted by gold quantum dots 112 into beneficial red light with a photoluminescence emission peak at around 700 nm and a range of 620-800 nm.

[0138] This innovation of tuning the optical spectrum extends beyond agricultural applications, also finding relevance in diverse domains such as glass buildings. When it comes to glass buildings, the focus shifts to the visible spectrum. Optical engineering offers the opportunity to convert wavelengths below 400 nm, UV and far UV, into visible light. This not only prevents potential health issues but also addresses concerns such as furniture corrosion.

[0139] The concept of utilizing OPVs in glass buildings encompasses the integration of OPV panels at every glass surface of the building such as windows. The OPV can be integrated either retrofitted as shown in FIG. 10a or embedded inside a double-glazed window as an intermediate part of its structure as shown in FIG. 10b.

[0140] A typical example of Synthesis, Tuning and Control of Metallic Quantum Dots Properties is represented hereafter. A typical method for synthesizing metallic quantum dots involves several steps. An indicative example comprises the synthesis of gold quantum dots which is analyzed below in view of FIG. 6:

[0141] (a) Preparation of a Gold Precursor Solution, wherein a solution of a gold precursor, such as HAuCI4, is prepared in the appropriate concentration inside a suitable solvent, notably including water or ethanol. The above solution is then mixed with a stabilizing agent such as Bovine Serum Albumin 113 BSA solution and the gold precursor solution is formed. Controlled vigorous stirring conditions lead to the reduction of Au3+112 to Au1+115 of most of the gold atoms, due to the reducing and stabilizing activities of BSA protein.

[0142] (b) a Reduction Reaction, wherein a reducing agent, such as sodium hydroxide, borohydride or citrate, is added to the gold precursor solution under controlled conditions of temperature, pH, stirring and reaction time. This facilitates the controlled formation of gold nanoparticles 118. During this reaction, gold atoms are reduced from Au1+115 to Au° 116 to form clusters, which can be confirmed by the color change of the solution.

[0143] BSA acts as both a reducing and stabilizing agent, playing a crucial part in controlling the size of BSA-Au quantum dots 114. The addition of NaOH raises the pH, enhancing the reducing capability of BSA. The concentration of gold atoms exhibits a progressive increase over time in accordance with the reaction duration. Subsequently, the gold precursor becomes depleted and undergoes reduction once the reducing agent is introduced.

[0144] (c) Size and Shape Control, wherein the size and shape of the gold nanoparticles are controlled by adjusting reaction parameters, including the concentration of the reducing agent, stirring, temperature and incubation time.

[0145] Representative Dynamic Light Scattering measurements of quantum dots solution depicted in FIG.8 suggest a size distribution with an average value of hydrodynamic diameter at about 4,8 nm and 5,6 nm, which corresponds to a metallic core size at —1 ,5 nm and 3,0 nm, respectively.

[0146] (d) Purification, wherein the synthesized gold quantum dots solution is purified through processes like centrifugation, filtration and washing, removing any unreacted precursors or byproducts.

[0147] Gold Quantum Dots (AuQDs) colloidal solution absorption and transmission properties are set out hereafter: from absorbance and transmission spectra represented in FIG. 9a and 9b for two indicative distinct sizes of gold quantum dots, it can be seen that the gold quantum dots’ solution does not show plasmonic behavior as normal metallic nanoparticles, but due to their extremely small size display continuum absorption mainly in region below 400 nm, which corresponds to the ultraviolet wavelengths. The absorption spectrum of Au QDs exhibits a slight change for different sizes of quantum dots mainly in the onset, where the absorption of quantum dots begins.

[0148] The above optical properties suggest preferential features for a variety of applications in optoelectronics, such as in Agriculture, e.g. Greenhouses, Open Field Cultivations, Breeding, Glass Buildings, UV Health-care protection, tourism, transportation, food processing and packaging.

[0149] A method for Synthesizing Quantum Dot 112 - Enhanced Solution for optoelectronic devices’ intermediate Layer 108 is set out hereafter. An indicative example for synthesizing a quantum dot-enhanced solution to be used as an intermediate layer 108 of an optoelectronic device, includes the synthesis of quantum dot 112-enhanced electron transport layer solution for OPV. This case is analyzed below:

[0150] (a) Synthesis of QDs, wherein Quantum dots 112 of specific sizes and shapes are synthesized using a wet chemical synthesis method as described previously.

[0151] (b) Preparation of an Electron Transport Layer 108 Solution, wherein the electron transport layer 108 is prepared by dispersing the appropriate amount of the synthesized QDs 112 in the solution of an electron transport material, such as a metal oxide, and mild stirring afterwards.

[0152] (c) Deposition of Electron Transport Layer 108, wherein the electron transport layer solution is deposited onto a plastic substrate 107 using a Roll-to-Roll compatible printing technique such as slot-die or blade coating. This results in the formation of a uniform thin film.

[0153] (d) Annealing, wherein the deposited layer is annealed at optimized temperature and duration conditions to enhance the properties of the electron transport material with embedded QDs 112.

[0154] (e) Application in optoelectronic devices, wherein the resulting quantum dot-enhanced solution electron transport layer 108 can be employed, in OPV devices or other optoelectronic applications to improve device performance and optical properties.

[0155] The present invention thereby provides a comprehensive approach to fabricating enhanced OPVs or other optoelectronic devices, creating quantum dot layers 108, such as the ETL and applying the technology in various applications, such as energy-efficient greenhouse environments or open field cultivations, and glass building. One of the most promising applications is the integration of the enhanced optoelectronic device like OPVs as string / arrays in a greenhouse or in open field cultivation. This can be further supported by, though not limited to, a curved greenhouse structure, deployed closer to the roof or above an open field cultivation. In both applications, an OPV tilting system can be adjusted that enables the control of light transmittance form 20-100%, while blocking the UV radiation, which is destructive for plant mechanisms like growth and productivity. This integration provides adjustable shading, protecting plants from UV radiation and generating energy. An enhanced-OPV system also enables optimal PAR exposure, promotes germination, enhances crop production, regulates greenhouse microclimate, manages nutrients, and is easy to install and operate. Studies on tomatoes, peppers, eggplants, have shown more than 35% increase in crop production with OPV deployment in a Greenhouse. Additionally, the OPVs' high electricity generation capacity and air circulation during the day ensure sufficient cooling for crops and prevent sunburn caused by temperature surges. Furthermore, regarding the breeding methods, exposure of animals under UV-radiation can cause genetic abnormalities and reduced reproduction. Also, extreme heat condition by UV-radiation may disrupt gestation. Enhanced OPVs can provide shading and cut-off UV-radiation to prevent the above negative effects resulting in efficient breeding conditions.

[0156] Additionally, the innovation of tuning the optical spectrum extends its relevance to various applications like glass buildings, where emphasis is focused on the conversion of UV and far UV wavelengths below 400 nm into visible light. The integration of enhanced-OPV panels into glass buildings retrofitted onto existing structures or embedded within double-glazed windows as an integral component, mitigates health risks and addressing issues such as furniture corrosion while enable efficient energy harvesting.

[0157] References

[0158] 1. Logothetidis, S. (Ed.). (2014). Handbook of flexible organic electronics: Materials, manufacturing and applications. Elsevier

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[0160] 3. Ch. Varlamis, “Concepts for OPV, Smart Cities & Sustainability”, OPE Journal (2021)

[0161] 4. C. Baxevanou et. al. “Simulation of Radiation and Crop Activity in a Greenhouse Covered with Semitransparent Organic Photovoltaics, Appl. Sci. 2020, 10, 2550; doi:10.3390 / app 10072550

[0162] 5. C. Zisis et. al., “Organic Photovoltaics on Green Rooftops: Effects on Plant Growth”, Materials Today: Proceeding 19 (2019) 62.

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Claims

CLAIMS1. A fabrication method of an optoelectronic device with a multi-layer structure provided with additives comprising the following steps:- depositing a nanolayer esp. nanocoating of electron transport material (108) as an intermediate layer, on a substrate (107), esp. wherein said nanolayer deposition consists of a layer (film) having a nanometer thickness and formed by the deposition of material,- depositing an active nanolayer (109) solution (A’) on top of the electron transport layer (108),- depositing a hole transport nanolayer (110) solution (B’) on top of the active layer (109),- depositing a layer of anode material (111), on top of the hole transport layer (110), characterized in that said additives (112) are made of nano-sized particles of the type referred to as quantum dots (QD), which are sized at a few nanometers, typically 2-10 nm, that are incorporated in at least one of said layers, particularly in one of said intermediate layers, more particularly in said electron transport material layer (108), wherein a wet chemical synthesis is applied through which said so-called quantum dots (112) are synthesized with a targeted size and shape, after which the synthesized quantum dots (QD) are dispersed into said solution, which is mixed, wherein said quantum dots (QD) remain as individual additives without getting mutually agglomerated during said mixing, thereby forming a Quantum Dot enhanced Solution, wherein each said nanolayer solution is dried after said mixing through intermediate drying between layer depositions, thereby constituting a multi-layer structure of said optoelectronic device (113), particularly wherein said multiple layers (108, 109, 110, 111) that are formed by drying the respective fluids of said solutions (A’, B’,..) are sequentially deposited onto the substrate (107).

2. Method according to claim 1 , characterized in that said intermediate layer (108) is formed as a thin film, particularly substantially uniformly, by synthesizing the Quantum Dot-Enhanced Solution, wherein- said electron transport material layer (108) is deposited as an intermediate layer on said substrate (107), which consists of a plastic substrate that is coated with an indium tin oxide (ITO), thereby forming a uniform thin film; or- said active layer (109) solution is deposited on said electron transport layer film (108) as a substantially uniform thin film; or- said hole transport layer (110) solution is deposited on said active layer (109) as a substantially uniform thin film; or- said anode material layer (111), esp. of silver or gold, is deposited on hole transport layer (110),- wherein said additives (112) are incorporated as said so-called quantum dots (QDs) at least in said intermediate layer (108), wherein said Quantum Dot enhanced Solution is a photoactive layer (109), an emissive layer and / or the electron (108) or hole transport layer (110) of the optoelectronic device (113) as well.

3. Method according to claim 1v2, characterized in that said intermediate layer (108) is formed as a thin film, particularly substantially uniformly, by synthesizing the Quantum Dot- Enhanced Solution, wherein- said electron transport material layer (108) is deposited as an intermediate layer on said substrate (107), which consists of a plastic substrate that is coated with an indium tin oxide (ITO), thereby forming a uniform thin film;- said active layer (109) solution is deposited on said electron transport layer film (108) as a substantially uniform thin film.- said hole transport layer (110) solution is deposited on said active layer (109) as a substantially uniform thin film; and- said anode material layer (111), esp. of silver or gold, is deposited on hole transport layer (110),- wherein said additives (112) are incorporated as nanosized particles referred to as said quantum dots (QDs) at least in said intermediate layer (108), wherein said Quantum Dot enhanced Solution is a photoactive layer (109), an emissive layer and / or the electron or hole transport layer (108, resp. 110) of the optoelectronic device (113).

4. Method according to one of the claims 1 to 3, characterized in that said multi-layer structure of said optoelectronic device (113) is encapsulated esp. by means of laminated barrier films using multilayer flexible membranes that include inorganic barrier layers and moisture absorbers, thereby isolating said multi-layer structure (100) for protecting said optoelectronic device.

5. Method according to one of the preceding claims 1 to 4, characterized in that said respective fluids comprise solvents that are compatible with each other, thereby preventing a previously deposited / printed layer from being damaged by a solvent of a subsequently deposited or printed layer.

6. Method according to the preceding claim 5, characterized in that the electron transport layer (108) is made with a blend, which blend is quantum dot (QD) enhanced, notably consisting of a quantum dot (QD) enhanced metal oxide, andin that a blend of SnO, SnC>2, AZO or MoO nanoparticles, on the one hand, and gold, silver or other metallic quantum dots (QD), on the other hand, is incorporated in said quantum dot (QD) enhanced metal oxide, wherein it is formed by(i) blending the metal oxide nanoparticles solution contained in a first solvent comprising water or alcohol with the metallic quantum dots (QD) contained in a second solvent that is compatible with the said first solvent,(ii) mild stirring through which a uniform blend is created, after drying same and depositing the blend, thereby generating the formation of a homogeneous layer (108).

7. Method according to one of the preceding claims 1 to 4, characterized in that any or each layer of the multiple layer structure (100) of said optoelectronic device (113) is fabricated by slotdie, or screen printing; possibly_by blade coating, inject printing, gravure, flexography.

8. Method of fabrication of an optoelectronic device with said multi-layer structure enhanced with said so-called quantum dots (QD) as nano-sized additives (112), according to one of the claims 1 to 4, characterized in that it is made with the following components comprising the following steps:(a) starting from the substrate (107) that is a flexible substrate, which is selected notably from an ITO-coated plastic PET or PEN substrate;(b) then the electron transport layer (108) solution consisting of a metal oxide that is blended with said so-called quantum dots (112), particularly gold nanoparticles, that are tailored with specific sizes and concentrations;(c) the active layer (109) is then formed by depositing a solution of a conjugated polymer or small molecule or micromolecule, notably P3HT polymer and fullerenes like PCBM, esp. by applying a Roll to Roll (R2R) compatible printing technique, particularly slot-die coating;(d) then the hole transport interfacial layer (110) comprising organic materials like PEDOT:PSS, which is deposited on the active layer (109) facilitating hole transport; and finally(e) an Anode Layer (111) which is made of a metal or metal oxide material, esp. aluminum or silver.

9. Method according to one of the claims 1 to 6, characterized in that an Organic photovoltaic panel (OPV) is selected as the optoelectronic device (113), wherein metallic quantum dots (QD) (112) are embedded, thereby generating an increased power conversion efficiency corresponding to an enhanced power output for said optoelectronic device by an upgrade up to 20% percentage, esp. in comparison with a reference OPV without quantum dots.

10. Method according to the preceding claim for synthesizing gold quantum dots (112), characterized in that it comprises the following steps:(a) Preparation of a solution of a gold precursor, such as HAuCk in the prescribed concentration notably 5-20 mM inside a selected solvent, including water or ethanol, wherein said solution is then mixed with a stabilizing agent such as Bovine Serum Albumin (113) (BSA) solution and the gold precursor solution is formed, wherein Controlled stirring conditions are implemented leading to the reduction of Au3+(112) to Au1+(115) of a majority of the gold atoms, resulting from reducing and stabilizing activities of BSA protein;(b) a Reduction Reaction, wherein a reducing agent, such as sodium hydroxide, borohydride or citrate, is added to the gold precursor solution under controlled conditions of temperature, pH, stirring and reaction time, thereby facilitating the controlled formation of gold nanoparticles (118), during which reaction, gold atoms are reduced from Au1+(115) to Au° (116) to form clusters, wherein BSA acts as a reducing and stabilizing agent, contributing to controlling the size of BSA- Au quantum dots (114), wherein a base esp. NaOH is added which raises the pH, enhancing the reducing capability of BSA, wherein the concentration of gold atoms increases progressively over time in accordance with the reaction duration, after which the gold precursor is getting depleted and undergoes reduction once the reducing agent is introduced;(c) wherein the size and shape of the gold nanoparticles are controlled by adjusting reaction parameters, including the concentration of the reducing agent, stirring, temperature and incubation time;(d) after which the synthesized gold quantum dots solution is purified through a process involving centrifugation, filtration and washing, removing any unreacted precursors or byproducts.

11. Method according to one of the claims 1 to 5, characterized in that the quantum dots’ (QD) (112) solution is made colloidal with targeted size, design and QD-characteristics, and synthesized by means of a wet chemical process, in particular by co-precipitation, more particularly wherein said colloidal quantum dots (112) are made of various sizes, esp. with hydrodynamic diameters of 4,8 nm, and / or to 5,6 nm.

12. Method for synthesizing a quantum dot-enhanced solution for the intermediate layer (108) of said optoelectronic device (113), according to one of the preceding claims particularly 1 , characterized in that it comprises the following steps:(a) synthesis of the Quantum dots (112) of specific sizes and shapes that are synthesized using the above-mentioned wet chemical synthesis;(b) preparation of the electron transport layer (108) solution (A) by dispersing the prescribed amount typically 1-5 % v / v of the synthesized Quantum dots (112) in the solution (A) of an electron transport material, such as a metal oxide, and mild stirring afterwards;(c) deposition of the electron transport layer solution (108) onto a plastic substrate (107) using a Roll-to-Roll compatible printing technique such as slot-die or blade coating, thus generating the formation of a uniform thin film;(d) annealing the deposited layer at optimized temperature and duration conditions, thereby enhancing the properties of the electron transport material with embedded Quantum dots (112).

13. Method according to one of the claims 1 to 10, characterized in that metallic quantum dots (QD) are introduced inside the intermediate layer (108) of said optoelectronic device (113) thereby generating the absorption of Far-LIV and UV-light and its conversion to visible light wavelengths (A).

14. Method according to one of the preceding claims, esp. claims 12 or 13, characterized in that the optical spectrum is tuned by controlling the size of synthesized quantum dots (QD), thereby transforming UV or visible wavelengths to longer visible wavelengths (A).

15. Method according to the preceding claim 14, characterized in that the QDs synthesis is modified by varying and tailor-made emission characteristics, thereby producing QDs, esp. tailored OPVs, that integrate QDs of specific sizes meeting unique wavelength requirements.

16. Method according to claim 14 or 15, characterized in that said transformation of wavelength is carried out as a conversion of UV, green and yellow wavelengths to red and blue wavelengths, which are transmitted through an OPV panel and are especially selected.

17. Method according to one of the preceding claims 1 to 16, characterized in that said optoelectronic device is fully printed, wherein all the individual layers of the multilayer structure of the respective optoelectronic device are deposited using printing techniques compatible with roll-to-roll printing, such as slot-die, blade coating, or screen printing.

18. Optoelectronic device manufactured with a method as defined according to one of the preceding claims 1 to 17, characterized in that it consists of an Organic photovoltaic panel (OPV), a Perovskite photovoltaic panel (PPV) or an Organic Light Emitting Diode (OLED).

19. Device according to the preceding claim 18, characterized in that said optoelectronic device consisting of an Organic photovoltaic panel (OPV), esp. semitransparent, which is bifacial i.e. having two sides (101A, 101 B), in that it generates energy from both sides of said panel, wherein the one side (101A) is configurated to operate at a peak efficiency and to capture a maximum power, whereas the opposite side (101 B) contributes thereto as well by harnessing diffuse light, wherein this dual-sided panel means (101A, 101 B) enhances the overall efficiency of the OPV system, maximizing energy production, even including from indirect light sources.

20. Optoelectronic system for operating a device according to claim 18 or 19, characterized in that said optoelectronic device (121) is provided with a tilting system (123) by means whereof light transmittance is controlled completely esp. regarding climatic conditions and season, wherein said panels (105) have an angle and tilt, wherein said angle and tilt thereof (105) are adjusted, thereby generating a dynamic tracking mechanism by means whereof enhanced light is absorbed and utilized, thereby increasing the overall energy efficiency.

21. Optoelectronic system for operating a device according to claim 18 or 19, resp. 20, characterized in that the application of OPV consists of said_tilting system (123) in open field cultivation, and Greenhouse, esp. of fruits and / or vegetables, wherein said integrated OPV system (121) is arranged on a frame (122), notably metallic, wooden, or concrete, on top of said open field cultivation, for both energy generation as well as an enhanced crop yield.

22. Use of said device resp. system according to claim 18 or 19, resp. 20, wherein a shading effect is generated by said enhanced optoelectronic device (113) on its streamdownward radiated environment, esp. on plants, by means whereof the associated crop production is increased, esp. exceeding 30% and / or water consumption decreased resp., depending on a reduced evapo-transpiration thereby improving growth conditions, with simultaneous efficient energy harvesting.

23. Use of said device resp. system according to claim 18 or 19, resp. 20 with a method as defined according to one of the claims 1 to 17, characterized in that said optoelectronic device (113) is enhanced for carrying out specific applications comprising Agriculture, notably Greenhouses, Open Field Cultivations, Breeding, esp. wherein said optoelectronic device (113) (OPV) comprising PPV, OLEDs is integrated in structures for Greenhouses, Open Field Cultivations and Breeding for the agricultural applications, as well as Glass Buildings, transportation, food processing and packaging.

24. Use of said device or system for an installation according to the preceding claim, characterized in that said optoelectronic device (113) is integrated at the greenhouse metallic structure, esp. by means of their fixation into aluminum frames, in particular aluminum beams of tailored dimensions, that are positioned in predetermined locations by means whereof said OPV panels are stabilized uniformly esp. across a greenhouse roof, above an open field cultivation, or above a corral.

25. Use of said device or system according to claim 22 or 23, characterized in that said enhanced optoelectronic device (113), resp. system is integrated in a glass building, or wherein said enhanced optoelectronic device (113) is integrated in a glass building either by applying a retrofitted method onto an already existing structure, or by integrating said enhanced optoelectronic device (113) which is embedded within double-glazed windows as an integral component of said Glass Buildings.

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