Germanium monoselenide(GeSe)is an emerging promising photovoltaic absorber material due to its attractive optoelectronic properties as well as non-toxic and earth-abundant constitutes.However,all previously reported G...Germanium monoselenide(GeSe)is an emerging promising photovoltaic absorber material due to its attractive optoelectronic properties as well as non-toxic and earth-abundant constitutes.However,all previously reported GeSe solar cells rely on a superstrate configuration coupled with a CdS buffer layer,and suffer from unsatisfactory performance.Here we demonstrate that this low efficiency arises from the inevitable high-temperature treatment of p-n junction in superstrate configuration.This results in the diffusion of Cd atoms from CdS layer into GeSe film that introduces detrimental deep trap states inside the bandgap of GeSe(~0.34 eV below conduction band minimum).We adopt therefore a substrate configuration that enables the deposition of CdS atop pre-deposited polycrystalline GeSe film at room temperature,avoiding the Cd diffusion.By optimizing the annealing temperature of complete devices via a highthroughput screening method,the resulting substrate solar cells annealed at 150℃achieve an efficiency of 3.1%,two times that of the best previously reported superstrate GeSe results.展开更多
基金supported by the National Natural Science Foundation of China (21922512 and 21875264)the Youth Innovation Promotion Association CAS (2017050)
文摘Germanium monoselenide(GeSe)is an emerging promising photovoltaic absorber material due to its attractive optoelectronic properties as well as non-toxic and earth-abundant constitutes.However,all previously reported GeSe solar cells rely on a superstrate configuration coupled with a CdS buffer layer,and suffer from unsatisfactory performance.Here we demonstrate that this low efficiency arises from the inevitable high-temperature treatment of p-n junction in superstrate configuration.This results in the diffusion of Cd atoms from CdS layer into GeSe film that introduces detrimental deep trap states inside the bandgap of GeSe(~0.34 eV below conduction band minimum).We adopt therefore a substrate configuration that enables the deposition of CdS atop pre-deposited polycrystalline GeSe film at room temperature,avoiding the Cd diffusion.By optimizing the annealing temperature of complete devices via a highthroughput screening method,the resulting substrate solar cells annealed at 150℃achieve an efficiency of 3.1%,two times that of the best previously reported superstrate GeSe results.
