FAPbI3 perovskite thin film having α/δ phase junction and its light harvesting performance in solar cell

Abstract

In this study, FAPbI3 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 PbI2 and FAPbI3 films have been investigated. The XRD, SEM and UV–Visible analyses have shown that the FAPbI3 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 PbI2 to FAPbI3 form has enhanced with increasing annealing temperature. Moreover, the α/δ phase junction form crystalline depend annealing temperature has been observed in FAPbI3 films and the α/δ phase junction has enhanced with increasing annealing temperature. In second stage, performance of the FAPbI3 films have been investigated as active layer in solar cell having structure of Glass/ITOPEDOT:PSS(~ 50 nm)/FAPbI3(~ 400 nm)/PC61BM(~ 70 nm)/Al(~ 100 nm). The best solar cell has performance parameters; Jsc is 18.12 mA/cm2, Voc is 0.74 V, FF is 59% and PCE is 7.91%. The results showed that presence of dominant δ phase in FAPbI3-based solar cells has caused S-sharped J–V character.