Seeded Space‐Limited Crystallization of CH₃NH₃PbI₃ Single‐Crystal Plates for Perovskite Solar Cells

Abstract

might, however, still affect the transport of charge carriers, thereby limiting the device efficiencies. A very long electron diffusion length, greater than 175 µm, has been reported for a CH 3 NH 3 PbI 3 single crystal (SC); [7] it decreases to ≈100 nm in polycrystalline films, due to these traps. [8] Therefore, higher efficiencies are expected for PeSCs incorporating perovskite SCs. Indeed, SC perovskitebased electronic devices have attracted much attention recently. [7,[9][10][11][12][13][14][15][16][17][18] In addition to solar cells, high-performance photodetectors [14][15][16][17] and X-ray detectors [18] featuring perovskite SCs have also been demonstrated. Perovskite SCs also exhibit greater thermostability and humidity stability when compared with their thin films. As a result, the challenge remains to develop relevant technologies for synthesizing and fabricating high-quality perovskite SCs for future applications.Many approaches have been proposed for growing perovskite SCs, [19] including temperature-lowering methods, [7] antisolvent vapor-assisted crystallization, [9] and inverse temperature crystallization. [20] The fabrication of efficient solar cells from perovskite SCs has, however, been mostly unsatisfactory, due to the imbalance between the absorption length and the carrier diffusion length; the thickness of the SCs is usually too great, resulting in poor charge carrier collection efficiencies. Laterally structured CH 3 NH 3 PbI 3 SC solar cells have been constructed through piezoelectric poling, but the PCEs obtained have remained low. [10] Several methods for growing planar/thin-film perovskite SCs effectively have been demonstrated recently. [11,12,16] For example, CH 3 NH 3 PbBr 3 SCs having thicknesses ranging from one to several tens of micrometers and lateral dimensions of up to several millimeters have been grown using cavitation-triggered asymmetric crystallization (CTAC), which provides additional energy to overcome the nucleation barrier; a PCE of 6.5% has been achieved for solar cells fabricated using this method. [11] Furthermore, space-limited inverse-temperature crystallization (SLITC) has been used to grow planar CH 3 NH 3 PbBr 3 SCs having a controllable thickness of 16 µm and lateral dimensions of 6 × 8 mm; a remarkable PCE of 7.11% was reported for such a device, which also displayed excellent stability. [12] Therefore, these novel approaches can allow the preparation of perovskite SC geometries having lateral crystal structures for applications in electronic devices.The synthesis of certain perovskite single crystals (SCs), including CH 3 NH 3 PbI 3 , through asymmetric crystallization is difficult, mainly because of the large difference in solubility of the precursors and/or the intrinsic nonpreference for growth in a direction along the substrate. Herein, an effective method is reported, seeded space-limited inverse-temperature crystallization (SSLITC), for growing CH 3 NH 3 PbI 3 SC plates having micrometer-scale diameters. In this process, a seed CH 3 NH 3 PbI 3 crystal ...

Recent Advances in Halide Perovskite Single‐Crystal Thin Films: Fabrication Methods and Optoelectronic Applications

“…To date, the inverse temperature crystallization method has been widely evidenced as a universal procedure for the fabrication of various bulk halide‐perovskite single crystals as well as single‐crystal MAPbBr 3 thin film, while the applicability of this method towards growing narrow‐bandgap iodine‐based single‐crystal perovskite (such as MAPbI 3 ) thin films is challenging. Yue et al found that the difficulties in single‐crystal MAPbI 3 film preparation originated from a high nucleation‐energy barrier owing to the distinct solubilities of MAI and PbI 2 in GBL. To solve this obstacle, MAPbI 3 seed crystals were introduced into the confined space to bypass the nucleation barrier, and single‐crystal MAPbI 3 thin films with thicknesses of 50 μm and lateral dimensions of up to 2 mm were obtained through the inverse temperature crystallization process …”

“…Yue et al found that the difficulties in single‐crystal MAPbI 3 film preparation originated from a high nucleation‐energy barrier owing to the distinct solubilities of MAI and PbI 2 in GBL. To solve this obstacle, MAPbI 3 seed crystals were introduced into the confined space to bypass the nucleation barrier, and single‐crystal MAPbI 3 thin films with thicknesses of 50 μm and lateral dimensions of up to 2 mm were obtained through the inverse temperature crystallization process …”

Recent progress of two‐dimensional lead halide perovskite single crystals: Crystal growth, physical properties, and device applications

“…However, a number of key problems, such as the lack of resistance to water, light and heat, and many grain boundaries and defects of polycrystalline and nanocrystalline thin films, have hindered large‐scale industrial production of PSCs. PSCs with single‐crystal thin film as the light absorption layer have mainly been constructed with MAPbI 3 5, 96 and MAPbBr 3 6, 97, 98 . Although the PCE of 3D single‐crystal PSCs has increased rapidly to 21.09% in the past 23 years, it is still far lower than that of polycrystalline silicon cells 99–101 …”

Defect Engineering of Grain Boundaries in Lead‐Free Halide Double Perovskites for Better Optoelectronic Performance

“…Polycrystalline semiconductors generally exhibit poorer electronic or optoelectronic properties compared to their single‐crystal counterparts . For example, it is reported that single crystals of hybrid organic–inorganic halide perovskite CH 3 NH 3 PbI 3 , a promising high‐efficient photovoltaic (PV) absorber, are far superior to their polycrystalline thinfilm counterparts in terms of trap‐state density, carrier diffusion length, lifetime, and carrier mobility .…”