Ultrasonic Spray-Coated Mixed Cation Perovskite Films and Solar Cells

Abstract

A solar absorber composed of mixed cation perovskite films containing methylammonium (MA) and formamidinium (FA) lead triiodide (MA1–x FA x PbI3) was prepared by continuous ultrasonic spray-coating. This process combined features of substitutional modifications in perovskites and simple yet versatile processing to realize scalable fabrication. Herein, simultaneous growth from a precursor solution with controlled MA/FA stoichiometry in the inverted perovskite solar cells based on MA1–x FA x PbI3 was systematically investigated to link the thin film quality, optical properties, and crystal structures with photovoltaic performance. The result of the inherent advantages of increased photoabsorption, better film quality, and enhanced crystallinity, the perovskite solar cell composed of the MA0.75FA0.25PbI3 (x = 0.25) perovskite achieved an optimum power conversion efficiency (PCE) as high as 15.61% and an average PCE of 15.15 ± 0.45%. In particular, the spray-deposited MA0.75FA0.25PbI3 unencapsulated cells exhibited almost no hysteresis in the current density–voltage (J–V) curve and excellent long-term stability under ambient conditions (25 °C, 30–40% relative humidity). These results highlight the importance of choosing a suitable mixed cation perovskite composition and scalable spraying technique for high-throughput manufacturing of perovskite solar cells to prolong device lifetime and achieve good reproducibility.

Eco‐Friendly Spray Deposition of Perovskite Films on Macroscale Textured Surfaces

“…[5] In this communication, we present an innovative method to deposition metal halide perovskite thin films on microscale textured surfaces by using a sequential eco-friendly spray coating (SEF-SC) technique. Contrasting with previously reported studies on spray-coated perovskite solar cells, [6][7][8][9] our approach completely avoids the use of hazardous solvents. Spray coating is already an established scalable technique which can be easily adopted for various applications.…”

Progress and challenges on scaling up of perovskite solar cell technology

“…Ishihara et al 53 studied the fluid dynamics of droplets and Girotto et al 49 described the relationship between spray velocity and precursor solution spreading capabilities. Besides, factors affecting the deposition were systematically optimized, such as precursor solution (viscosity, concentration, compositions) 54,55 , substrate (wettability, roughness, temperature) 56,57 , boiling point of solution 58 , distance between the nozzle and substrate 59 . Park et al 56 prepared high-quality PVK layers by controlling the flow rate of precursor solution and the reaction temperature.…”

Progress in Spray Coated Perovskite Films for Solar Cell Applications

“…The optimized photovoltaic performance of the mixed cation MA 0.75 FA 0.25 PbI 3 PSC featured a PCE of 15.6%, negligible hysteresis, and long‐term stability as evidenced by the retention of >80% of its original PCE after 35 days. [ 26 ] In another example, Bishop et al demonstrated for the first time the ultrasonic spray deposition of the Cs‐containing triple cation perovskite, CsI 0.05 ((FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 ) 0.95 . Brief exposure of the partially wet spray‐cast films to low vacuum also proved useful in promoting the formation of smooth films composed of densely packed perovskite crystals.…”