Improved Performance of Kesterite Cu2znsn(S,Se)4 Solar Cells via Enhanced Carrier Management

Cu2ZnSn(S,Se)4 (CZTSSe) materials have been extensively studied for use in next-generation solar cells. Their properties, such as tunable direct band gap of 1.0–1.5 eV, which matches well with incident solar radiation, and large absorption coefficient make CZTSSe an attractive choice for thin film solar cells. Most importantly, the elements of CZTSSe are earth-abundant, inexpensive and environmentally benign. However, the current efficiency of CZTSSe champion solar cell, ~12.7%, is much lower than its theoretically predicted Shockley–Queisser (SQ) limit, ~32%. This performance gap is caused by the narrow phase stability of the quaternary kesterite phase, Cu2ZnSn(SxSe1-x)4, and the existence of other competitive and complex secondary phases and defect-complexes along with interfacial carrier recombination. The main objective of this 3-years project is to improve the performance of CZTSSe photovoltaic devices by amending the photogenerated carrier management with defect and interface engineering. Besides, a novel Cd-free process and surface micro/nano-structures are adopted to develop non-toxic, flexible and high efficiency kesterite photovoltaic devices. Research categories include both fundamental physics and practical implementation. It is important to comprehend different interfaces and recombination mechanisms. Defect and interface engineering is crucial in improving the efficiency CZTSSe solar cells. In addition, the impacts of these defects and defect-complexes on device performance should be correlated with the photogenerated carrier dynamics. The Raman spectra, time-resolved photoluminescence spectroscopy (TRPL), deep level transient spectroscopy (DLTS) and admittance spectroscopy (AS) measurement techniques help to understand the physics of defects and defect-complexes, their density and relative energy levels in the absorbing material. Finally, carrier management through defect and interface engineering will help to achieve ultra-high efficiency in CZTSSe material.

Project ID:PA10901-1259
External Project ID:MOST108-2112-M182-001-MY3