Differential Space‐Limited Crystallization of Mixed‐Cation Lead Iodide Single‐Crystal Micro‐Plates Enhances the Performance of Perovskite Solar Cells

Abstract

The synthesis of certain asymmetric perovskite single crystals (SCs)-including CH 3 NH 3 PbI 3 , which is used most commonly-for application in highperformance perovskite solar cells (PeSCs), remains very challenging. Herein, a promising but general method, differential space-limited crystallization (DSLC), is described for synthesizing high-quality perovskite single-crystal micro-plates. The thickness of the perovskite SCs is controlled by the difference between the thicknesses of two sets of polytetrafluoroethylene (PTFE) spacers. Because the DSLC method does not require very thin spacers, it simplifies the procedure of crystal growth. More importantly, the hydrophobicity of the PTFE spacers weakens the attraction between the surfaces of the confined space and the precursor complexes, thereby increasing the rate of diffusion of the precursor ions. Accordingly, the critical nucleation step is not limited by the low rate of diffusion of the ions. This approach is used to prepare mixed-cation lead iodide single-crystalline micro-plates for solar cell applications. The device performance of single-crystal PeSCs improves after introducing formamidinium ions. The stability of the single-crystal devices also improves relative to that of conventional thin-film counterparts. It is anticipated that this DSLC method can also be used to synthesize different types of asymmetrical perovskite SCs for other optoelectronic applications.

Polymer-Controlled Growth and Wrapping of Perovskite Single Crystals Leading to Better Device Stability and Performance

“…Recently, it has been reported that the polymeric Lewis base adduct formation with the perovskite precursors can increase the activation energy for nucleation and lead to high crystallinity and improved optoelectronic properties in polycrystalline film. , Organic–inorganic halide perovskites are a promising semiconductor material due to their high light absorption coefficient, large charge carrier lifetime, long carrier diffusion length, and high carrier mobility, which enable a broad range of photovoltaic and optoelectronic applications. − In particular, methylammonium lead iodide (MAPbI 3 ) perovskite single crystals show exceptionally low density of traps and long carrier diffusion length and are much better than its polycrystalline thin films due to the absence of grain boundaries and fewer defects in the single crystals. , Typically, the perovskite single crystals are synthesized by lowering solution temperature, antisolvent diffusion, inverse temperature crystallization, and geometry-defined dynamic flow reaction system . One common limitation with most of these methods is that they are time-consuming and take several days to grow the high-quality MAPbI 3 single crystals and hence do not meet the demands of large-scale production.…”

Asymmetrical Single Crystals Containing Tilted Ruddlesden–Popper Phases for Efficient Perovskite Solar Cells

“…During the synthesis of asymmetrical SCs, the perovskite precursor solution is positioned between two substrates, with the thickness controlled by altering the geometric space (i.e., the distance between the two substrates). [ 33–38 ] As a result, SCs are obtained in a form of thin films, which can improve the charge collection efficiencies and minimize the degree of charge recombination. In the present work, we propose a space‐confined method (V 2 SLC) to grow 2D perovskite SCs.…”

“…To validate our assumption, we performed a diffusion test, following the approach described previously (Figure S2, Supporting Information). [ 31,34 ] The upper and lower surfaces of the channels were VB‐FNPD and PTFE, respectively. Precursor solutions were used containing various molar ratios of PEAI.…”

Strategies for high‐performance perovskite solar cells from materials, film engineering to carrier dynamics and photon management

“…The obtained grain is over 2 μm, the maximum PCE of the HPSCs reaches to 20.44%. Sung et al 246 developed a promising and general method of differential space‐limited crystallization to synthesize the high‐quality perovskite single‐crystalline micro‐plates. Therein, the thickness of perovskite films was controlled by the difference between thicknesses of two spacers.…”