Influence of precursor concentration on printable mesoscopic perovskite solar cells
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RESEARCH ARTICLE
Influence of precursor concentration on printable mesoscopic perovskite solar cells Shuangquan JIANG*, Yusong SHENG*, Yue HU, Yaoguang RONG, Anyi MEI (✉), Hongwei HAN Michael Grätzel Center for Mesoscopic Solar Cells, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
© Higher Education Press 2020
Abstract Over the last decade, the power conversion efficiency of hybrid organic–inorganic perovskite solar cells (PSCs) has increased dramatically from 3.8% to 25.2%. This rapid progress has been possible due to the accurate control of the morphology and crystallinity of solution-processed perovskites, which are significantly affected by the concentration of the precursor used. This study explores the influence of precursor concentrations on the performance of printable hole-conductor-free mesoscopic PSCs via a simple one-step drop-coating method. The results reveal that lower concentrations lead to larger grains with inferior pore filling, while higher concentrations result in smaller grains with improved pore filling. Among concentrations ranging from 0.24–1.20 M1), devices based on a moderate strength of 0.70 M were confirmed to exhibit the best efficiency at 16.32%. Keywords printable perovskite solar cell (PSC), precursor concentration, crystallization, morphology
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Introduction
Over the past decade, perovskite solar cells (PSCs) have been the focus of much research [1–8]. The record-certified power conversion efficiency (PCE) of PSCs has increased rapidly to 25.2%, rivaling the optimum efficiency of silicon-based solar cells [2]. This rapid increase in efficiency is largely attributed to the improved control of the crystallinity and morphology of halide perovskites, which generally have the formula of ABX3, where A is a Received February 8, 2020; accepted April 28, 2020 E-mail: [email protected] *
These authors contributed equally.
1) 1 M = 1 mol/L
monovalent cation, such as methylammonium (MA+); B is a divalent metal, such as lead (Pb2+); and X is a halogen anion, such as iodide (I–) [9–11]. Generally, properties of good crystallinity, such as large grain size, along with welldeveloped orientation are required for inhibiting nonradiative recombination and promoting charge-carrier transport in halide perovskite films [12,13]. Additionally, morphological preferences, such as good uniformity and effective coverage, are essential for absorbing light and inhibiting shunt caused by undesired contact between the other layers in PSCs [12,13]. Since halide perovskites are solution-processable, most PSCs are currently prepared via solution-processed methods [2]. The composition of the precursor is fundamental in the processing of solutions [14,15]. For example, the precursor of MAPbI3 is usually prepared by directly dissolving methylammonium iodide (MAI) and lead iodide (PbI2) in selected solvents, such as dimethylformamide (DMF) or g-butyrolactone (GBL) [16–18]. An intensive study on the precursor of MAPbI3 revealed that the precursor is not a pu
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