FAPbI_3 perovskite thin film having α/δ phase junction and its light harvesting performance in solar cell

摘要

In this study, FAPbI_3 perovskite thin films having α/δ phase junction have been prepared by the two-step solution method at short annealing time. In first stage, the structural, morphological and optical properties of the PbI_2 and FAPbI_3 films have been investigated. The XRD, SEM and UV-Visible analyses have shown that the FAPbI_3 film quality has improved with increasing annealing temperature and the film annealed at 170 °C have bandgap of 1.49 eV and high covering capability with average grain size of ～ 61 nm. The transition from PbI_2 to FAPbI_3 form has enhanced with increasing annealing temperature. Moreover, the α/δ phase junction form crystalline depend annealing temperature has been observed in FAPbI_3 films and the α/δ phase junction has enhanced with increasing annealing temperature. In second stage, performance of the FAPbI_3 films have been investigated as active layer in solar cell having structure of Glass/ITOPEDOT:PSS(～ 50 nm)/FAPbI_3(～ 400 nm)/PC_(61)BM(～ 70 nm)/ Al(～ 100 nm). The best solar cell has performance parameters; J_(sc) is 18.12 mA/ cm~2, V_(oc) is 0.74 V, FF is 59% and PCE is 7.91%. The results showed that presence of dominant δ phase in FAPbI_3-based solar cells has caused S-sharped J-V character.