Effects of defect states on the performance of perovskite solar cells**Project supported by the National Natural Science Foundation of China (Nos. 11164014, 11364025), the Gansu Science and Technology Pillar Program (No. 1204GKCA057), and the Gansu Supercomputer Center.

Abstract

We built an ideal perovskite solar cell model and investigated the effects of defect states on the solar cell's performance. The verities of defect states with a different energy level in the band gap and those in the absorption layer CH3NH3PbI3 (MAPbI3), the interface between the buffer layer/MAPbI3, and the interface between the hole transport material (HTM) and MAPbI3, were studied. We have quantitatively analyzed these effects on perovskite solar cells' performance parameters. They are open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency. We found that the performances of perovskite solar cells change worse with defect state density increasing, but when defect state density is lower than 1016 cm−3, the effects are small. Defect states in the absorption layer have much larger effects than those in the adjacent interface layers. The perovskite solar cells have better performance as its working temperature is reduced. When the thickness of MAPbI3 is about 0.3 μm, perovskite solar cells show better comprehensive performance, while the thickness 0.05 μm for Spiro-OMeTAD is enough.