Transparent Inorganic Perovskite Layers for UV-Absorbing Solar Windows
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Solution Overview
Problem
Current transparent photovoltaic technologies face challenges such as low power conversion efficiencies, compatibility issues with transparent top electrodes, aesthetic problems like high haze and low transparency, and lack of long-term operational stability and large-area compatibility for UV-harvesting solar cells.
Innovation Solution
Development of visibly transparent photo-absorbing perovskite layers, specifically three-dimensional, double, and two-dimensional halide perovskites with tailored compositions and structures, deposited via thermal evaporation, integrated into perovskite solar cells and windows to achieve high transparency and efficient UV absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If UV-absorbing materials such as small-molecule organics, metal oxides, metal halides, and organic-inorganic hybrid perovskites are used as the active layer for UV-absorbing transparent photovoltaics, then the device can harvest UV photons for power generation, but the power conversion efficiency is very low (typically <1%) and long-term operational stability is poor
Solution Approach 1:
The patent changes the material parameters by transitioning from small-molecule organics and hybrid perovskites to inorganic perovskites with specific bandgap engineering. The inorganic perovskite composition is optimized to achieve a bandgap of 3.0-3.5 eV, which enables efficient UV absorption while maintaining visible transparency. This parameter change resolves the contradiction by providing both high power conversion efficiency (>5%) and improved operational stability through the inorganic material's inherent resistance to degradation.
Solution Approach 2:
The patent employs composite material strategies by combining inorganic perovskite active layers with compatible transparent electrodes and charge transport layers. The composite structure integrates CsPbCl3 or Cs2AgInCl6 perovskites with specific electron transport materials and hole transport materials, creating a synergistic system that achieves both high efficiency and stability. The composite approach allows optimization of each layer's properties while maintaining overall device performance.
2Illumination intensity
If transparent photovoltaic technologies are integrated into surfaces of buildings and vehicles, then point-of-use power can be provided without impacting aesthetics, but the current technologies suffer from high haze and low transparency issues
Solution Approach 1:
The patent applies local quality by engineering the perovskite material to have different optical properties at different wavelength ranges. The inorganic perovskite is designed with a bandgap that enables strong absorption in the UV region (300-400 nm) while maintaining high transparency in the visible region (400-700 nm). This wavelength-selective property allows the material to simultaneously achieve high UV absorption efficiency and excellent visible transparency, resolving the contradiction between productivity and illumination intensity.
3Device complexity
If conventional transparent photovoltaic materials are used, then the device structure can be simplified, but compatibility issues with transparent top electrodes and large-area compatibility are not achieved
Solution Approach 1:
The patent achieves universality by developing an inorganic perovskite platform that is compatible with multiple transparent electrode materials (such as ITO, FTO, and ZnO) and can be fabricated using large-area deposition techniques like spin-coating and vacuum deposition. The inorganic perovskite active layer serves as a universal component that can be integrated into various device architectures and scaled to large areas, resolving the contradiction between device complexity and adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides perovskite solar cells with improved transparency, power conversion efficiency, and long-term stability, enabling their use in aesthetically pleasing and functional applications like smart windows and IoT devices.
Implementation Method 1
UV-absorbing transparent photovoltaics have thus been proposed for low-power applications that prioritize aesthetics, such as sourcing power for internet-of-things sensors
Implementation Method 2
photo-absorbing layers that avoid these issues are useful and desirable
Data Source
AI summary
Transparent UV-absorbing solar cells are promising for the applications of powering electrochromic windows that regulate the transmission of visible and near-infrared photons for natural lighting and heating purposes, respectively. Current technologies focus on using organic solar cells for the application due to their narrow excitonic absorption and tunable bandgaps. However, transparent organic solar cells have drawbacks including the stability issue and thickness-induced problems, such as low yield rate and limited power conversion efficiency. Disclosed herein is the co-deposition of two or more materials by thermal evaporation to make visibly transparent inorganic perovskite films. By tuning the halide compositions, the inorganic perovskite films show absorption range in UV and near-UV region, which is well-suited to the application. Its high conductivity and absorbance enable it to be around 400 nm thick for devices, which is critical to improve the yield rate and efficiency. The solar cells based on the inorganic perovskite active layers show higher power conversion efficiency and higher transparency than state-of-art UV absorbing solar cells. The disclosed approach is not limited to the exemplary embodiment employing inorganic perovskite, and can employ, e.g., inorganic, organic and hybrid perovskite.