28 results about "Exciton dissociation" patented technology

The invention relates to modified nitrogen-rich carbon nitride as well as a preparation method and photocatalytic application thereof. The preparation method comprises the following steps: mixing nitrogen-rich carbon nitride and fused salt, and performing secondary calcination to obtain an intermediate; the secondary calcining temperature is 550 DEG C to 600 DEG C; the fused salt comprises a potassium source; and washing and drying the intermediate to obtain the modified nitrogen-rich carbon nitride. According to the invention, potassium ion doping modification is carried out in nitrogen-rich carbon nitride, so that the nitrogen-rich carbon nitride has stronger photon-generated carrier separation and transmission capability because the internal transmission resistance is reduced due to high crystallinity of KC3N5 and K < + > is successfully introduced to serve as a transmission channel for interlayer electron transfer, after introduction of K < + >, Eb of C3N5 is significantly reduced, exciton dissociation and generation of photon-generated carriers are facilitated, and the performance of the material is improved. The effect of producing H2O2 through photocatalysis of the KC3N5 is enhanced; when the photocatalyst is applied to photocatalytic production of H2O2, the production rate of H2O2 can reach up to 117 times of that of C3N5, and the photocatalyst has excellent photocatalytic stability, can efficiently produce H2O2 in a wide pH range, and is suitable for various complex water substrates to remarkably improve the production rate of H2O2.

The invention relates to the technical field of photoelectric detection, and discloses a wide-spectrum photoelectric detector based on a crystalline silicon-organic composite heterojunction, which comprises a crystalline silicon avalanche photodiode (APD) layer and an organic semiconductor active layer. Through an energy band matching design, the organic layer covers the surface of the micro-nano structure of the crystalline silicon APD to form a synergistic photoelectric response interface. The structure utilizes the high gain characteristic of the crystalline silicon APD and the broadband spectrum absorption advantage of the organic material to realize the broadband spectrum detection from visible light to near infrared light. In addition, the light capture efficiency is remarkably enhanced through the micro-nano structure design, and the exciton dissociation efficiency is improved through interface electric field regulation and control. The invention solves the problems of narrow spectral range and low sensitivity of the traditional photoelectric detector, and is suitable for medical health monitoring and high-speed optical communication systems.

The invention discloses an application of diphenyl disulfide as an additive of an active layer of a photovoltaic cell and the photovoltaic cell, which comprises the step of adding a volatile solid additive diphenyl disulfide into the active layer to regulate and control the performance of the active layer. The solid additive is added in the acceptor film forming process, and acceptor molecule aggregation and crystallization behaviors are continuously regulated and controlled in the film forming process and the thermal annealing process. The introduction of diphenyl disulfide can synergistically optimize multi-stage crystallization kinetics, enhance H-aggregation and J-aggregation at the same time, promote the formation of a receptor fibrous polycrystalline structure, improve the carrier mobility, and effectively improve the exciton dissociation and charge transfer capabilities of the active layer. Based on the regulation and control, the organic photovoltaic device using the diphenyl disulfide as the additive realizes the significant improvement of photovoltaic performance, the energy conversion efficiency reaches 19%, a new development direction is provided for the design of a multifunctional solid additive and the accurate control of the form of an active layer in the future, and a powerful technical support is provided for organic photovoltaic industrialization in the future.

The invention belongs to the technical field of photocatalytic materials, and particularly relates to a method based on one-step in-situ synthesis of a copper cyanophenylacetylene / copper phenylacetylene (CN-PhCCu / PhCCu) homogeneous heterojunction composite photocatalyst and application. The homogeneous heterojunction composite photocatalyst with a compact interface structure is synthesized in situ in one step under a mild condition by regulating and controlling the ratio of copper cyanophenylacetylene (CN-PhCCu) to copper phenylacetylene (PhCCu). The heterojunction can effectively promote exciton dissociation and photo-induced electron delocalization, remarkably inhibit charge recombination and improve the utilization efficiency of visible light. Experiments show that the composite photocatalyst shows excellent degradation performance on various water pollutants such as diclofenac (DCF) under irradiation of visible light, and has the advantages of high degradation efficiency, wide pH application range, strong coexisting ion interference resistance and the like. The method disclosed by the invention is simple in process and mild in condition, and provides a new material and technical support for efficient visible light driven water body pollution control.

A tin-containing asymmetric donor material has a structural formula as follow:where X represents fluorine or chlorine. The small-molecule tin-containing donor material designed by the present disclosure can form an appropriate energy level difference from an acceptor material L8-BO, which is conducive to the exciton dissociation. In addition, the small-molecule tin-containing donor material exhibits excellent photovoltaic performance in an organic solar cell test. When used in all-small-molecule organic solar cells, the small-molecule tin-containing donor material enables well-defined molecular structures and small batch-to-batch variations for materials and devices. Therefore, the small-molecule tin-containing donor material has unique advantages in commercialization. The small-molecule tin-containing donor material is of great significance for the building of high-efficiency organic solar cell systems.

The invention discloses application of an imide-based large-dipole-moment volatile solid additive in a bulk heterojunction organic solar cell, and belongs to the technical field of solar cell solid additives. The large-dipole-moment additive can better act on donor and acceptor molecules, the morphology of an active layer is improved, exciton dissociation and charge transfer are optimized, and finally the energy conversion efficiency of the organic solar cell is enhanced. The good volatility can prevent the additive from continuously influencing the morphology of the active layer and damaging the long-term stability of the organic solar cell. The development of the imide type additive also widens the variety of additives. More importantly, the imide type additive can induce a receptor to nucleate and then grow, so that a receptor domain with a uniform size is formed, and carrier transport is optimized.

The invention belongs to the technical field of organic solar cells, and particularly discloses a metal type coordination additive material and a preparation method and application thereof. The coordination additive material takes Y6 as a starting material, and is obtained through a reduction reaction, a 1, 10-phenanthroline-5, 6-diketone ring closing reaction and a 4, 4, 4-trifluoro-1-(thiophene-2-yl) butane-1, 3-diketone coordination reaction. When the additive material is added into the active layer, JSC and FF can be enhanced. According to the preparation method, a good phase separation morphology and a high-purity structural domain are promoted to be formed, construction of a high-quality interpenetrating network is facilitated, more efficient and more balanced carrier transport is realized, dissociation of excitons is effectively promoted, and charge recombination is inhibited. Meanwhile, the electron transport performance is enhanced, and the non-radiation voltage loss is reduced. The synthesis process provided by the invention is simple and easy to purify, and has a good practical application prospect.

The invention discloses a chiral lead-free perovskite flexible X-ray detector based on enantiomer proportion regulation and a preparation method thereof, and belongs to the technical field of photoelectric detectors, and the method comprises the following steps: introducing proportion-adjustable chiral organic cations (S-CHEA and R-CHEA) into a Bi / Sb-based lead-free perovskite precursor to form (S1-rR r-CHEA) 4 (Bi < 0.5 > Sb < 0.5 >) 2I < 10 > perovskite; according to the method, a local asymmetric electric field and an ordered chiral environment are formed in the material by regulating and controlling the proportion and crystal structure of the enantiomers, and the local inversion symmetry of the crystal is destroyed by the effect, so that the spin degeneracy of an electron energy band is broken, the momentum overturning process related to spin is promoted, the exciton dissociation and carrier separation efficiency is enhanced, and the efficiency of the material is improved. And a new regulation and control way is provided for improving the performance of the device. According to the mechanism, the separation and transmission efficiency of current carriers is remarkably improved, the charge collection performance of the detector in X-ray detection is further enhanced, and a foundation is laid for large-scale preparation and commercial application of devices.

This invention discloses a solid additive material for photoelectric converters, its application, and its preparation. The solid additive material for photoelectric converters comprises compounds having the structure shown in the following formula: the structure of the photoelectric converter, from bottom to top, includes a transparent substrate, a transparent electrode layer, a hole transport layer, a photoactive layer, an electron transport layer, and a metal electrode layer; the material of the photoactive layer includes a donor material, an acceptor material, and the solid additive material for photoelectric converters. The solid additive material for photoelectric converters of this invention can effectively control the morphology of the active layer, thereby improving the performance of photovoltaic devices. After addition, the acceptor molecules in the active layer are arranged more compactly and orderly, thereby improving the internal carrier physics processes, enhancing exciton dissociation, improving charge transport, and reducing charge recombination, thus significantly increasing the short-circuit current density and fill factor of the photoelectric converter, and obtaining higher photoelectric conversion efficiency.

The invention discloses a solar cell additive and a preparation method and application thereof, and belongs to the technical field of organic photoelectric devices. According to the application of siloxane in the solar cell additive, siloxane has the following structural formula, Ar is an aromatic unit and comprises an electron-rich conjugated unit or an electron-deficient conjugated unit; r is selected from alkylene of C1-10, alkyleneoxy of C1-10, alkylenesulfenyl of C1-10, and alkylene group of C1-10; siO is a siloxy group; and n is the number of silicon and oxygen in a side chain and is equal to 1-4. The invention provides a siloxane additive which can be used in an active layer of an organic semiconductor device and can effectively promote exciton dissociation and transportation, reduce charge recombination and promote and improve the morphology and crystallinity of a thin film, so that the performance of the device is improved. The siloxane additive can be subjected to intermolecular interaction, the morphology is regulated and controlled, and the stability of the device can be effectively improved; the silica group has low surface energy and hydrophobic property, and is beneficial to large-area processing in air. # imgabs0 #

A preparation method and application of a zinc oxide-coated copper plasma composite photocatalytic material for phenol degradation, which relates to a preparation method and application of a photocatalytic material. The present invention aims to solve the problem that the existing semiconductor catalyst has a competitive relationship between excitons and free charge carriers, resulting in a single deficiency of ROS generated by the semiconductor in the photocatalytic system. The present invention uses ZnO, a direct bandgap semiconductor with a good exciton dissociation effect, as a substrate, and introduces bulk oxygen vacancies and elemental copper with a plasmon resonance effect in situ to precisely control the balance between excitons and photogenerated carriers, thereby achieving the generation of enriched oxidative active species in the photocatalytic system. Method: 1. Material mixing; 2. Hydrothermal reaction. Application: It is used as a photocatalyst for the photocatalytic degradation of phenol. The present invention discloses the preparation and application of a zinc oxide-coated copper plasma composite photocatalytic material for phenol degradation.

The invention belongs to the technical field of preparation of active layers, and particularly relates to an active layer based on polymer aggregation structure regulation and a preparation method and application thereof. Comprising the following steps: S1, reacting chlorobenzene with 2-bromothiophene according to a ratio of (10-n): n (0lt; n is less than or equal to 10) to obtain a mixed solvent; s2, mixing and stirring the mixed solvent and the donor powder to obtain a donor precursor solution; s3, preparing an acceptor precursor solution; and S4, sequentially spin-coating the donor precursor solution and the acceptor precursor solution to prepare the active layer film. The active layer is prepared by accurately regulating and controlling a polymer aggregation structure through an optimized solvent, efficient internal exciton dissociation and charge collection are realized, and the active layer film is applied to a solar cell device or an organic light-emitting diode device, so that the overall performance of the device can be remarkably improved.

The invention discloses an organic photovoltaic device based on a chloroform ethyl benzene mixed solvent system and a preparation method thereof, and belongs to the technical field of organic photovoltaic devices. According to the method, an electron donor material and a non-fullerene acceptor material are jointly dissolved in a mixed solvent composed of chloroform (CF) and ethylbenzene (EB) to prepare a stable blended solution, and a spin-coating method is adopted to prepare the high-quality organic active layer film. By optimizing the ratio of chloroform to ethyl benzene, the synergistic regulation of donor and acceptor molecules in a solution state and a solidification state is realized, the phase separation structure, crystallinity and morphology uniformity of the active layer film are remarkably improved, and exciton dissociation and charge transfer are promoted. According to the mixed solvent system strategy, the efficiency of the device is improved from 17.43% to 19.09%, and the performance of the device is remarkably improved.

This invention belongs to the field of photocatalytic materials technology, specifically relating to a method and application of a one-step in-situ synthesis of a homo-heterojunction composite photocatalyst based on cyanophenylacetylene copper / phenylacetylene copper (CN-PhC₂Cu / PhC₂Cu). This invention achieves one-step in-situ synthesis of a homo-heterojunction composite photocatalyst with a tight interface structure under mild conditions by controlling the ratio of cyanophenylacetylene copper (CN-PhC₂Cu) to phenylacetylene copper (PhC₂Cu). This heterojunction effectively promotes exciton dissociation and photogenerated electron delocalization, significantly suppresses charge recombination, and improves visible light utilization efficiency. Experiments show that this composite photocatalyst exhibits excellent degradation performance for various water pollutants such as diclofenac (DCF) under visible light irradiation, possessing advantages such as high degradation efficiency, wide pH adaptability, and strong resistance to interference from coexisting ions. The method of this invention is simple and operates under mild conditions, providing new materials and technical support for efficient visible light-driven water pollution control.

The present application relates to the technical field of organic solar cell, and particularly relates to a four-arm small molecule compound and a preparation method and application thereof. The four-arm small molecule compound is prepared from benzene [1,2-b:4,5-b'] dithiophene-4,8-diyl bis (trifluoromethanesulfonate) as a starting material through Suzuki coupling reaction, acetalization protection reaction, Vilsmeier haack acylation reaction, deprotection reaction and Knoevenage condensation reaction. The four-arm compound material is added into an active layer as an additive to optimize the stacking behavior and reduce energy disorder. The present application realizes the synergistic control of nanoscale phase separation morphology and photophysical process through the four-arm small molecule compound, inhibits the excessive aggregation of polymers, promotes the formation of a double-continuous interpenetrating network of a donor-acceptor, balances the exciton dissociation and charge transport efficiency, and thus high-efficiency organic solar cells can be prepared.

The invention discloses an organic solar cell active layer based on a thiophene solvent mediated donor molecular chain and a preparation method and application thereof, and the preparation method comprises the steps: dissolving a donor D18 in a mixed solvent of 2, 5-dichlorothiophene and chlorobenzene, heating and stirring an obtained 5-8mg / mLD18 solution, and spin-coating the solution on a substrate at 80-100 DEG C to obtain a donor layer; and dissolving a receptor L8-BO in chloroform to obtain an L8-BO solution, adding 1-chloronaphthalene to obtain a mixed solution, stirring the mixed solution, spin-coating the donor layer with the mixed solution, and performing vacuum drying to obtain the organic solar cell active layer. 2, 5-dichlorothiophene is used for mediating a donor D18 molecular chain to form a stable pre-aggregation structure, so that acceptor molecule permeation is promoted, ideal donor-acceptor phase separation scale and crystallinity control is synergistically realized, further, an active layer microstructure with good continuity is constructed, and efficient exciton dissociation and transmission are realized. When the active layer is applied to the organic solar cell, the photoelectric conversion performance of the organic solar cell is remarkably improved.

The present invention discloses a heterojunction for improving charge transport, a preparation method thereof, and a perovskite solar cell, relating to the field of perovskite solar cells. The heterojunction for improving charge transport includes: an SnO2 electron transport layer and a perovskite light-absorbing layer, and a dipole layer is compounded between the SnO2 electron transport layer and the perovskite light-absorbing layer, and the material of the dipole layer is 4-methylsulfonylphenylamidine. The present invention successfully realizes the synchronous increase of the dielectric constant of the heterojunction by using 4-methylsulfonylphenylamidine (SPA) dipole molecules, and adjusts the dielectric properties of the heterojunction to an equilibrium state; effectively reduces the exciton dissociation energy of the perovskite photoactive layer, and promotes the dissociation of excitons to generate free electrons and holes; successfully shields the capture of electrons by interface state traps and inhibits the recombination loss; effectively reduces the interfacial charge transport barrier and promotes the energy level alignment; effectively solves the problem of low efficiency of interfacial charge transport performance and improves the photoelectric conversion efficiency of the device during long-term operation.

The application of a class of imide-based large dipole moment volatile solid additives in bulk heterojunction organic solar cells belongs to the technical field of solar cell solid additives. The large dipole moment additive can better act on the acceptor molecule, improve the active layer morphology, optimize the exciton dissociation and charge transport, and finally enhance the energy conversion efficiency of the organic solar cell. Good volatility can avoid the continuous influence of the additive on the active layer morphology, and damage the long-term stability of the organic solar cell. The development of the imide type additive also widens the types of additives. More importantly, the imide type additive can induce the acceptor to nucleate first and then grow, forming uniform size acceptor domains, and optimizing the carrier transport.

The invention discloses a non-fullerene acceptor material based on a two-dimensional conjugated core with an imidazole five-membered ring as well as a preparation method and application of the non-fullerene acceptor material, and belongs to the technical field of photovoltaic materials. The preparation method comprises the steps of amine reduction, Schiff base reaction, Knoevenagel condensation reaction and the like which are carried out under anhydrous and anaerobic conditions, the whole synthesis route is simple and convenient, the cost is low, and large-scale preparation can be realized. Based on good advantages of an imidazole five-membered ring structure and a two-dimensional conjugate plane of a molecular main body framework in molecular design, the acceptor material has good molecular accumulation, exciton dissociation, charge mobility and charge recombination are further controlled, and PCE of a device is improved. When the actually prepared BTQT-4F is used as an acceptor material to be applied to binary and ternary organic solar cells, the efficiencies respectively reach 18.22% and 19.40%, which shows that the BTQT-4F has huge actual development value.

This invention belongs to the field of organic solar cell technology, and particularly relates to a layered organic solar cell based on a bithiazole additive and its fabrication method. The active layer of this cell includes a D18 donor layer and an acceptor layer containing L8-BO and a bithiazole additive (DBB), wherein the additive is only present in the acceptor layer. A layer-by-layer spin-coating process is employed, and the morphology of the acceptor layer is controlled by solid-state additives to solve the solvent residue problem. This achieves synergistic optimization of the exciton dissociation interface and charge transport channels, resulting in a photoelectric conversion efficiency of 19.7% and significantly improved stability.

The invention provides a quasi-two-dimensional perovskite solar cell with a double-spacer cation formal structure and a method. Double spacer cations are adopted for co-nucleation to form a mixed 2D phase containing two spacer cations. The special low-dimensional perovskite has the remarkable advantages that firstly, rigid thiophene ring positive ions and flexible alkyl positive ions are mixed, and a large amount of residual strain in the thin film is successfully released, so that the surface appearance of the thin film is obviously improved; secondly, the distribution of the n phase of perovskite is optimized, and reverse ordered phase distribution which is most beneficial to exciton dissociation and carrier transportation is successfully established through p-n junctions formed in the thin film from top to bottom; and thirdly, more matched energy level alignment between the perovskite layer and the transmission layer is realized by adjusting the perovskite energy level distribution. The above factors finally cause the photoelectric conversion efficiency (PCE) of the double-spacer cation RP PSCs to reach 18.67%, and the problems existing in the single-spacer cation perovskite are successfully solved.

The invention discloses injectable near-infrared light response photoelectric nanoparticle hydrogel and a preparation method thereof, and belongs to the technical field of medical materials.The preparation method comprises the steps that a photoelectric nanoparticle aqueous dispersion containing a surfactant and an organic photoelectric semiconductor is added into a mixed solution of a NaOH aqueous solution and an HBSS solution, then rat tail collagen is added, the mixture is stirred to be uniform, and the injectable near-infrared light response photoelectric nanoparticle hydrogel is obtained. And then uniformly mixing with a PBS (Phosphate Buffer Solution) for crosslinking. By adjusting a donor-acceptor material system and a phase separation scale, the particles realize efficient exciton dissociation and photon-generated carrier generation in a brain tissue optical window (approximately equal to 850 nm). According to the invention, rat tail collagen is used as a biocompatible matrix, near-infrared response BHJ photoelectric nanoparticles are introduced into a gel forming process, and injectable photoelectric-collagen composite gel with fluidity, rapid gel forming and uniformly distributed photoelectric functions is constructed and can be used as a three-dimensional hydrogel material system with near-infrared light triggered electric response characteristics. And a material basis is provided for related biomedical engineering application.

The present application relates to the technical field of optoelectronic devices and organic semiconductor, in particular to a high bias-resistance single photosensitive material organic photodetector and a preparation method, and its technical key points are: using single-component organic thin film as single-component photosensitive unit, and connecting in series with light-light gain variable resistance unit; by using single-component photosensitive unit and light-light gain variable resistance unit in series structure, using the nonlinear impedance characteristics (high impedance in dark state, low impedance under illumination) of light-light gain variable resistance unit, the technical problems of traditional single-component organic photodetector, such as dark current surge under high bias and inability to withstand high reverse bias, are successfully solved, so that the dark current can still be maintained at 10 ‑7 A / cm² order of magnitude and not breakdown, while significantly improving the efficiency of exciton dissociation, achieving the highest external quantum efficiency of more than 55% and 10 12 Jones detectivity, with the effects of narrow-band spectral response and high sensitivity.

The invention discloses a visible light-near infrared organic polymer photoelectric detector and a preparation method thereof, and relates to the field of organic photoelectric detectors, the organic photoelectric detector adopts an inverted structure, can effectively block dark-state carriers, and further greatly reduces the dark current density. The device comprises a transparent conductive cathode ITO, an electron transport layer, a bulk heterojunction BHJ active layer, a planar heterojunction PHJ active layer, a MoO3 hole transport layer and a metal anode, the BHJ active layer is spin-coated on the ITO upper layer through a wet method to form BHJ, and the BHJ can obviously increase the donor / receptor area, shorten the transmission distance and realize efficient exciton dissociation; a PHJ active layer thin film is obtained on the upper layer of the BHJ active layer through water transfer printing, a P-BHJ structure is formed by the PHJ active layer thin film and the BHJ active layer, low dark current is ensured, the transition time of current carriers is remarkably shortened through combination of the PHJ active layer thin film and the P-BHJ active layer, dissociation of excitons is enhanced, and finally the high-performance organic photoelectric detector is achieved.

The present invention relates to the technical field of organic optoelectronic materials, in particular to an asymmetric donor material with different fluorine contents, its preparation method and application, including an organic small molecule donor material with an asymmetric two-dimensional side chain containing different fluorine atoms, abbreviated as Z-2F, whose structural formula is shown in Formula 1, and the preparation method of the donor material; the application of the donor material in the preparation of the following functional energy devices also belongs to the protection scope of the present invention: solar cells, organic light-emitting diodes and flexible display fields, including applications in the field of floating photovoltaics. The small molecule donor material containing fluorine atoms designed in the present invention forms an appropriate energy level difference with the acceptor material L8-BO, which is beneficial to exciton dissociation, and has better photovoltaic performance and a wider range of floating photovoltaic applications in the testing of organic solar cells.

The invention provides an application of a solid additive in an organic solar cell and the solar cell. The structure of the solid additive provided by the invention is that a methoxy group and a halogen atom simultaneously exist in a benzene nucleus side group. The solid additive can effectively regulate and control the morphology of an active layer so as to improve the performance of a photovoltaic device, and after the solid additive is added, receptor molecules are arranged more tightly and orderly in the active layer, so that the physical process of internal carriers is improved, exciton dissociation is enhanced, charge transfer is improved, charge recombination is reduced, and the performance of the photovoltaic device is improved. Therefore, the short-circuit current density and the filling factor of a cell device are greatly improved, and relatively high photoelectric conversion efficiency is obtained. Besides, in the organic solar cell preparation method provided by the invention, the solid additive concentration, the annealing temperature and the annealing time are systematically optimized, so that the prepared organic solar cell has relatively high photoelectric conversion efficiency, and compared with a traditional liquid additive cell device, the photoelectric conversion efficiency is greatly improved.

The invention discloses an organic solar cell with a ternary composite material as a hole transport layer. The organic solar cell sequentially comprises an anode substrate, the hole transport layer, an organic active layer, an electron transport layer and a cathode layer from bottom to top, the material of the hole transport layer is a ternary composite hole transport material obtained by gold nano bipyramid, hexadecyl trimethyl ammonium chloride and PEDOT: PSS through ionic bond action, the sedimentation problem is solved, and meanwhile, the charge recombination loss is inhibited by improving the conductivity and promoting exciton dissociation and transport, so that the hole transport efficiency is improved. And the photoelectric conversion efficiency of the organic solar cell is obviously improved.

The present invention relates to a high-efficiency all-polymer organic solar cell structure and a preparation method thereof, comprising a substrate, an anode, a hole transport layer, an active layer, an electron transport layer and a cathode from bottom to top; PM6:PY-IT is added to the active layer. The present invention selects the polymer acceptor BL-102 as the third component material. When the incorporation amount of the third component is 3 wt%, while realizing complementary absorption with the main system to enhance the utilization of sunlight, it also affects the crystallinity of the donors and acceptors in the active layer, inhibits the aggregation of the donors and acceptors, forms a more ordered molecular packing, enhances the solubility of the donors and acceptors, thereby forming a more donor-acceptor interpenetrating nanoscale percolation network, and finally realizes efficient exciton dissociation and carrier transport in the ternary system.