Self-sacrifice PbI2 seed layer-assisted crystal growth for improved perovskite thin films for efficient and stable transportation layer-free photodetectors

Recently, the growth of improved perovskite thin films with high crystallinity and low defects has been an important research subject owing to their critical roles in achieving efficient and stable optoelectronic devices. In this work, we introduced a self-sacrifice PbI2 seed layer to prepare improved CH3NH3PbI3 thin films with high crystallinity and reduced defects. It showed that the PbI2 seed layer at the buried interface acted as nuclei and modulated the crystal growth of CH3NH3PbI3, which induced the vertically upward growth of CH3NH3PbI3, resulting in increased sizes of grains and reduced grain boundaries. Further observations verified the suppression of defect and trap states in the obtained CH3NH3PbI3 thin films. On this basis, efficient and stable transportation layer-free Au/CH3NH3PbI3/indium tin oxide photodetectors have been demonstrated, where the responsivity and detectivity are as high as 0.54 A/W and 7.5 × 1012 Jones, respectively, at the bias of 0 V. It is supposed that the self-sacrifice PbI2 seed layer-assisted crystal growth method will find applications in fabricating high-quality and stable perovskite thin film devices in the future.