The key challenge in reducing the cost of solar power lies in increasing the conversion efficiency of solar panels. Tandem solar cells are made from sub-cells that respond to different wavelengths of light and could double the efficiency of solar panels. Their deployment, however, has been limited by high fabrication costs. Perovskite solar cells hold promise for use in low-cost tandem solar cells due to ease of processing and chemical tuning of their absorption. Most perovskite solar cells are made from hybrid organic-inorganic materials which decompose at temperatures above 100°C and degrade in the presence of moisture. The aim of this project is to develop a perovskite device that is thermally stable to 300℃, and is relatively insensitive to moisture. The cell will be an all-inorganic structure, thereby potentially improving its stability against photo-induced degradation. The new device is likely to be useful for making tandem junction cells with silicon acting as the bottom cell in a tandem junction arrangement. The technology is likely to increase the efficiency of solar energy conversion and reduce its overall cost. The project will offer a significant opportunity for research to both graduate and undergraduate students, including those from underrepresented groups in STEM.
This project will develop photovoltaic devices based on a new inorganic perovskite—a bromide based inorganic perovskite alloy, Cs(Pb,Sn)Br3. Bandgap engineering will enable the fabrication of an optimized tandem structure. The bandgap of the CsPbBr3 can be reduced from 2.3 eV to 1.9 eV by incorporating tin, with further reductions possible by mixing cesium and rubidium. Inorganic heterojunction layers will be used to fabricate the devices. The material will be deposited using vacuum deposition processes which are easily scalable. Detailed structural and electronic characterization of the material and the device will be undertaken to understand the photovoltaic performance of the device. The devices will be tested for their stability against moisture and heat and against photoinduced degradation.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
