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Updated: Jul 7, 2026
Monovalent Cation Doping of CH3NH3PbI3 for Efficient Perovskite Solar Cells
Published on: March 19, 2017
Synergistic dual-surface passivation via 1-butyl-3-methylimidazolium iodide for efficient and stable inverted
Xin Liu1, Chengguo Liu1, Lang Wang1
1Optoelectronic Sensor Devices and Systems Key Laboratory of Sichuan Provincial Universities, Sichuan Meteorological Optoelectronic Sensor Technology and Application Engineering Research Center, Information Materials and Device Applications Key Laboratory of Sichuan Provincial Universities, College of Optoelectronic Engineering (Chengdu IC Valley Industrial College), Chengdu University of Information Technology Chengdu 610225 China liuxin@cuit.edu.cn yangdingyu@cuit.edu.cn.
Abstract:
All-inorganic CsPbI2Br perovskites have garnered significant interest for their superior thermal stability and suitable bandgap, rendering them promising candidates for tandem and indoor photovoltaics. However, the pronounced non-radiative recombination losses at both the buried hole transport layer (HTL)/perovskite and the top perovskite/electron transport layer (ETL) interfaces severely curtail the power conversion efficiency (PCE) of inverted p-i-n architecture devices. Herein, we systematically elucidate the distinct interfacial modification roles of imidazolium-based ionic liquids (ILs) with varying halide anions, 1-butyl-3-methylimidazolium iodide (BMIMI), bromide (BMIMBr), and chloride (BMIMCl). Density functional theory (DFT) calculations reveal that BMIMBr and BMIMCl unexpectedly lower the formation energy of iodine vacancies (V I) in CsPbI2Br, paradoxically promoting detrimental defect formation, whereas BMIMI maintains a benign profile and powerfully passivates both cationic and anionic defects through synergistic Lewis acid-base interactions. We decouple the effects of single- and dual-interface modification: bottom-interface BMIMI treatment predominantly enhances fill factor (FF) by improving hole extraction and perovskite crystallization, while top-interface modification substantially elevates open-circuit voltage (V oc) through effective surface defect passivation. Consequently, the synergistic dual surface modification (DSM) with BMIMI yields a champion PCE of 15.28% for inverted CsPbI2Br devices, representing a 23.12% enhancement over the control device (12.41%). The DSM devices exhibit a substantially mitigated hysteresis index of 2.03% and retain 91% of their initial efficiency after 2100 h of nitrogen storage.
