An efficient method for performance improvement of organometal halide perovskite solar cell via external electric field
An effective method, performed adding external electric field (EEF) on CH3NH3PbI3-xClx (OPIC) perovskite layer during the annealing process, is proposed to improve the performance of the solar cell. By harmonizing EEF direction with the hole/electron modified layer, a significant improvement on the short circuit current and fill factor is obtained. Using the simplest planar device, the largest positive EEF of 2.5*10^6 V/m makes PCE increase from 12.86 to 14.33, whose increment reaches 11.4% compared with non-EFE sample. By analyzing the best and the statistics data, a fine positive correlation between EEF and PEC is found. The physical mechanism which a displacement polarization field induced by the ionic migration enhances the built in field of the perovskite heterojunction is discussed. The study proposed a physical process in modifying the cell efficiency and provides a new evidence on current-voltage hysteresis of OPIC devices.