摘要
In this study, lead-free perovskite CsSn(I x Br 1− x ) 3 films with photoluminescence emission wavelengths from 677 to 887 nm are prepared. The influence of air exposure on their characteristics is also investigated. It is found that CsSnI 3 can be transformed to Cs 2 SnI 6 upon increasing the air exposure time. The decomposition and oxidation mechanisms are confirmed by the X-ray diffraction pattern due to the presence of CsI peak. It is observed that devices based on the CsSn(I x Br 1− x ) 3 film with increased Br − ratio and the CsSnI 3 film with prolonged air exposure time show inferior performance. These results are mainly attributed to the highest occupied molecular orbital levels of CsSn(I x Br 1− x ) 3 and Cs 2 SnI 6 . Defect density of state and binding energy of these materials are also investigated and reported in this study.