Grain growth study of perovskite thin films prepared by flash evaporation and its effect on solar cell performance

Abstract

Flash-evaporated perovskite films with large grain sizes lead to high efficiency solar cell devices.

Scalable Deposition Methods for Large‐area Production of Perovskite Thin Films

“…[149] circumvents this challenge by heating up the final material alloy with a very high heat flux, which results in simultaneous evaporation of all of the perovskite components and the subsequent condensation of the materials on the substrate to form a thin film (illustrated in Figure 14a). Xu et al [152] followed this work and developed an approach to increase the grain size with a flash evaporation process by varying the pressure and the precursor composition ratios. They used a 1.2-mmthick layer of MAPI, prepared by meniscus coating which is subsequently placed on a large tungsten sheet and later heated rapidly under high vacuum conditions (0.1 mbar) to instantaneously evaporate and then deposit as thin-film onto a substrate.…”

“…Due to the high vapor pressure of MAI, a heated and covered petri dish was sufficient to achieve the conversion in a contained environment and solar cells with g = 12% for smallarea devices were shown. [152] c) Illustration of close space sublimation process. The layers can be individually deposited either via solution or vapor and then converted similarly via solution or vapor exposure.…”

“…This vapor-assisted solution process (VASP) led to an understanding that the formation of hybrid perovskite thin films allows for much flexibility. [153] [155] Flash evaporation 2 ITO/PEDOT:PSS/MAPI/polyTPD/PCBM/Ba/Ag 0.09 12.2% [151] Flash evaporation 1 FTO/PCBM/MAPI/spiro-OMeTAD/Au 0.09 10.01% [152] Pulsed laser flash evaporation 1 FTO/NiO x /MAPI/C60/BC/Ag N/A N/A [156] Samples with * are stabilized power conversion efficiency. Others followed the same technique to refine the crystal growth and morphology to improve the defects and interfaces (shown in Figure 15b,c) [158] for devices with small-area PCE of g = 10.5% or to form higher bandgap MAPbBr perovskites [159] with small-area PCE of g = 8.7%.…”

All-Inorganic CsPbBr3 Perovskite Films Prepared by Single Source Thermal Ablation

“…This simple method was used for organometal halide perovskites by Mitzi et al (2001) who named it as single source thermal ablation (SSTA) technique. In the era of halide perovskites for PVs, only few papers reported the deposition of three dimensional halide perovskites by flash evaporation (Longo et al, 2015;Xu et al, 2016), all dealing with MAPbI 3 . Due to the high vapor pressure of MAI, high quality films require not only high currents to make MAI and PbI 2 evaporation as simultaneous as possible, but also a MAI excess in the precursor (up to MAI to PbI 2 molar ratio of 2.0) in order to compensate the inevitable loss of MAI during the deposition process.…”

Tuning Nucleation Sites to Enable Monolayer Perovskite Films for Highly Efficient Perovskite Solar Cells

“…For perovskite solar cells (PSCs) with planar configuration, which are low cost and more suitable for industrialization, both the high conversion efficiency and high environmental stability strongly depend on the full coverage state of the perovskite film (PVK) at both macroscopic and microscopic scales on the substrate [5,6]. Until now, many approaches have been attempted to realize the scalable full coverage perovskite film [7][8][9]. Considering the one-step solution fabrication process is a promising method for the preparation of perovskite film, due to its easy operation, low cost, and no reverse reaction [10,11], a number of approaches have been explored to control the steps that link the initial precursors to the final perovskite film during the solution fabrication process.…”