Understanding Microstructural Development of Perovskite Crystallization for High Performance Solar Cells

Abstract

Solution crystallization in film devices has attracted broad interest from various fields such as perovskite solar cells. However, the detailed perovskite crystallization kinetics remain unclear due to the difficulty of in situ observation of grain cluster growth during annealing. This article presents the development of an in situ laser scanning confocal polarized microscopy with a temperature‐controlled stage to observe nucleation and growth of perovskite crystal clusters. It is found that enhanced interactions by a liquid crystal with perovskite form a new intermediate complex that induces diffusion‐controlled growth according to Avrami equation. The retarded cluster growth (63 nm s−1) originates from enlarged diffusion activation energy 40 kJ mol−1 compared with 152 nm s−1 and 37 kJ mol−1 for the Control film during annealing. Finally, the optimized perovskite films with enhanced crystallographic and optical characteristics are applied in solar cells to achieve a champion efficiency of 24.53% with open circuit voltage of 1.172 V and fill factor of 82.78%. The bare device without any protection maintains 89% of its initial efficiency after 6600 h of aging in ambient environment. This work implies that the in situ observation using fluorescence microscopy is a critical for understanding of crystallization kinetics in film devices.

Synergetic Optimization of Upper and Lower Surfaces of the SnO2 Electron Transport Layer for High-Performance n–i–p Perovskite Solar Cells

“…The lower dark saturation current (9.7 × 10 −9 vs 3.4 × 10 −6 A), as shown in the Supporting Information (Figure S25), also indicates a lower trap density when the perovskite film is deposited on AlO x /SnO 2 -RbAc instead of SnO 2 -c. Additionally, electrochemical impedance spectroscopy (EIS) was conducted to measure the series resistance (R s ) and the transport resistance (R tr ). 57 Nyquist plots indicate that the R s and R tr of AlO x / SnO 2 -RbAc ETL are significantly smaller than those of SnO 2 -c (46.71 vs 60.58 Ω and 22,578 vs 25,030 Ω), as shown in the Supporting Information (Figure S26). Furthermore, the trapfilled limit voltage (V TFL ) of 1.05 and 2.05 V for PSCs utilizing AlO x /SnO 2 -RbAc and SnO 2 -c ETL, respectively, can be verified by SCLC curves, 58 as shown in the Supporting Information (Figure S27).…”

Custom-tailored solvent engineering for efficient wide-bandgap perovskite solar cells with a wide processing window and low VOC losses

“…Moreover, a new peak appears in the target films, and we speculate that this peak belongs to the PbI 2 –DMPU interphase. 8,20,21,26 Interestingly, the intensity of the PbI 2 –DMPU interphase decreases with the increase of the annealing time and finally disappears, indicating that DMPU slowly evaporates and simultaneously releases PbI 2 , thereby extending the growth time of perovskite grains to enhance film crystallinity. 26 Moreover, the more stable PbI 2 –DMPU interphase can effectively regulate the release of PbI 2 for promoting the formation of high-quality perovskite films during the annealing process.…”

Minireview and Perspectives of Liquid Crystals in Perovskite Solar Cells

“…Copyright 2023 Wiley-VCH. (j) Crystallization kinetics for the perovskite films obtained by Ma et al Panel j was adapted with permission from ref . Copyright 2023 Wiley-VCH.…”

“…Recently, Ma et al designed two types of organic molecules bearing similar functionalities (CO and CN) to compare the interaction between mesogenic and non-mesogenic molecules with perovskite. Among those two, 4′-cyano-[1,1′-biphenyl]-4-methacrylate (CBECV) is a non-mesogenic molecule (Figure ), while 4′-cyano-[1,1′-biphenyl]-4-acyl acrylate (LC10) is a mesogenic molecule (Figure ).…”