Low-Temperature Crystallization Enables 21.9% Efficient Single-Crystal MAPbI₃ Inverted Perovskite Solar Cells

Abstract

Lead halide perovskite solar cells (PSCs) have advanced rapidly in performance over the past decade. Single-crystal PSCs based on micrometers-thick grain-boundary-free films with long charge carrier diffusion lengths and enhanced light absorption (relative to polycrystalline films) have recently emerged as candidates for advancing PSCs further toward their theoretical limit. To date, the preferred method to grow MAPbI3 single-crystal films for PSCs involves solution processing at temperatures ≳120 °C, which adversely affects the films’ crystalline quality, especially at the surface, primarily because of methylammonium iodide loss at such high temperatures. Here we devise a solvent-engineering approach to reduce the crystallization temperature of MAPbI3 single-crystal films (<90 °C), yielding better quality films with longer carrier lifetimes. Single-crystal MAPbI3 inverted PSCs fabricated with this strategy show markedly enhanced open-circuit voltages (1.15 V vs 1.08 V for controls), leading to power conversion efficiencies of up to 21.9%, which are among the highest reported for MAPbI3-based devices.

Ultrathin Perovskite Monocrystals Boost the Solar Cell Performance

“…Organic/inorganic hybrid perovskites have emerged as highly efficient solar cell materials and achieved a staggering 25.2% power conversion efficiency (PCE) in the past few years. [ 1–5 ] However, the record efficiency is still lower than the detailed balance model predicted by Shockley–Queisser which believe the efficiency limit of perovskite solar cells can go up to 31%. [ 6 ] It is necessary to overcome the bottleneck that hinders the performance of perovskite solar cells.…”

Halide Perovskite Single Crystals: Optoelectronic Applications and Strategical Approaches

“…It was speculated that the easy-to-oxidize I − may result in I 3 − trimers that form deep-level defects [77,78], which the N 2 environment can prevent. Most recently, a new record of a PCE of 21.93% with a J SC of 23.68 mA cm −2 , a V OC of 1.144 V, and a FF of 81% was made by Bakr's group using the same device configuration [26]. They optimised the composition of the precursor solvent to a solvent mixture of propylene carbonate (PC) and γ-butyrolactone (GBL) for low-temperature crystallisation for high-quality single crystal thin film.…”

“…There are other obstacles like a defective surface with high trap density and the weak interaction with the functional layers, which causes interfacial voids hindering the progress. Recently, a 20 µm-thick MAPbI 3 (MA + : methylammonium, CH 3 NH 3 + ) monocrystalline made by space-limited low-temperature crystallisation was fabricated into inverted-structure solar cells with a PCE of 21.9% [26], thus narrowing the gap between the single crystals and polycrystalline thin films. The confined thickness increases the chances for carriers to be collected at electrodes, which can be controlled as small as tens-of-nm scale to hundreds-of-µm scale [27][28][29][30][31].…”

Facile and noninvasive passivation, doping and chemical tuning of macroscopic hybrid perovskite crystals

“…We note, however, that there has been recent interest in solar cells that employ~20 μm thick perovskite single crystals as the active layer. [49,50] Given the suppressed trap states and longer carrier diffusion lengths in single crystals, these cells have shown excellent carrier extraction. We believe that the Br-treatment developed in this paper is directly applicable to such single crystal solar cells for device performance improvements.…”