Understanding and Eliminating Hysteresis for Highly Efficient Planar Perovskite Solar Cells

• Published in: Advanced energy materials Vol. 7; no. 17
• Main Authors: Wang, Changlei, Xiao, Chuanxiao, Yu, Yue, Zhao, Dewei, Awni, Rasha A., Grice, Corey R., Ghimire, Kiran, Constantinou, Iordania, Liao, Weiqiang, Cimaroli, Alexander J., Liu, Pei, Chen, Jing, Podraza, Nikolas J., Jiang, Chun‐Sheng, Al‐Jassim, Mowafak M., Zhao, Xingzhong, Yan, Yanfa
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 06-09-2017; Wiley
• Subjects: Charge transport; Deposition; Electrical resistivity; Hysteresis; Kelvin probe force microscopy; Optimization; perovskite solar cells; Perovskites; Photovoltaic cells; post annealing; Solar cells; SOLAR ENERGY; Tin dioxide
• DOI: 10.1002/aenm.201700414
• EISSN: 1614-6840
• ISSN: 1614-6832

Through detailed device characterization using cross‐sectional Kelvin probe force microscopy (KPFM) and trap density of states measurements, we identify that the J–V hysteresis seen in planar organic–inorganic hybrid perovskite solar cells (PVSCs) using SnO2 electron selective layers (ESLs) synthesized by low‐temperature plasma‐enhanced atomic‐layer deposition (PEALD) method is mainly caused by the imbalanced charge transportation between the ESL/perovskite and the hole selective layer/perovskite interfaces. We find that this charge transportation imbalance is originated from the poor electrical conductivity of the low‐temperature PEALD SnO2 ESL. We further discover that a facile low‐temperature thermal annealing of SnO2 ESLs can effectively improve the electrical mobility of low‐temperature PEALD SnO2 ESLs and consequently significantly reduce or even eliminate the J–V hysteresis. With the reduction of J–V hysteresis and optimization of deposition process, planar PVSCs with stabilized output powers up to 20.3% are achieved. The results of this study provide insights for further enhancing the efficiency of planar PVSCs.
Through detailed characterizations, it is identified that the current density‐voltage hysteresis of planar perovskite solar cells using low‐temperature atomic‐layer deposited SnO2 electron selective layers originates from the poor‐electrical conductivity of the SnO2 layers. A facile low‐temperature thermal annealing in ambient air can effectively reduce the degrees of the hysteresis and improve the power conversion efficiency of planar perovskite solar cells.