Exploration of Crystallization Kinetics in Quasi Two-Dimensional Perovskite and High Performance Solar Cells

Abstract

Halide perovskites with reduced-dimensionality (e.g., quasi-2D, Q-2D) have promising stability while retaining their high performance as compared to their three-dimensional counterpart. Generally, they are obtained in (A)(A)PbI thin films by adjusting A site cations, however, the underlying crystallization kinetics mechanism is less explored. In this manuscript, we employed ternary cations halides perovskite (BA)(MA,FA)PbI Q-2D perovskites as an archetypal model, to understand the principles that link the crystal orientation to the carrier behavior in the polycrystalline film. We reveal that appropriate FA incorporation can effectively control the perovskite crystallization kinetics, which reduces nonradiative recombination centers to acquire high-quality films with a limited nonorientated phase. We further developed an in situ photoluminescence technique to observe that the Q-2D phase (n = 2, 3, 4) was formed first followed by the generation of n = ∞ perovskite in Q-2D perovskites. These findings substantially benefit the understanding of doping behavior in Q-2D perovskites crystal growth, and ultimately lead to the highest efficiency of 12.81% in (BA)(MA,FA)PbI Q-2D perovskites based photovoltaic devices.

Compositional and Solvent Engineering in Dion–Jacobson 2D Perovskites Boosts Solar Cell Efficiency and Stability

“…The photocurrent density-voltage (J-V) curves of the representative solar cells based on different absorber Table S2 in the Supporting Information. [32,35,36,42] Therefore, further work such as improving the grain size and quality of the films should be able to achieve higher J sc values and PCEs. Note that the average J sc of our solar cells is lower than that in other reports.…”

“…[35,46,47] To understand the carrier recombination process in the devices, we measured J sc under different light intensities (I) ranging from 50 to 100 mW cm −2 . [35,46,47] To understand the carrier recombination process in the devices, we measured J sc under different light intensities (I) ranging from 50 to 100 mW cm −2 .…”

“…The power law dependence between J sc and I has a relationship of J sc ∝ I α , [48][49][50] where α should be close to 1 if the devices have sufficient electron and hole mobilities and no space charge effect. [35] We then measured V oc under different I to compare the recombination process in different devices. [35] We then measured V oc under different I to compare the recombination process in different devices.…”

“…[34] Their 2D (PEA) 2 (MA) 2 Pb 3 I 10 devices showed much better stability with respect to the 3D MAPbI 3 devices. [35][36][37][38][39][40][41][42] Dion-Jacobson (DJ) 2D perovskites of the type BA n−1 M n X 3n+1 , including a divalent organic B cation, are a very new entry in the class of perovskites and are very promising for solar cell applications. [32] The hot-casting technique used to prepare (BA) 2 (MA) 3 Pb 4 I 13 solar cells achieved an impressive PCE of 12.52% with significantly improved short-circuit current density (J sc ) and an enhanced environmental stability.…”

Enhanced Charge Transport by Incorporating Formamidinium and Cesium Cations into Two‐Dimensional Perovskite Solar Cells

“…[10] Studies have shown that cesium (Cs) ions are effective in assisting the crystallization of perovskite because of the entropic stabilization. [13] Studies have shown that perovskites with triple cations (Cs + -FA + -MA + )c ould suppress yellow phase impurities and eliminate halide segregation, compared with binary cations in 3D perovskite-based solar cells. [12] By partially replacing methylammonium (MA + )w ith Cs + ,b oth the grain size and surface quality of 2D perovskite films are effectively improved, resulting in reduced trap state density,s uperior charge-carrier mobility,and improved thermal stability.Zhou et al reported that (formamidinium) FA + incorporation can effectively control BA 2 (MA x FA 1Àx ) 3 Pb 4 I 13 crystallization kinetics,a nd reduces nonradiative recombination centers to acquire high-quality films with al imited non-oriented phase.…”