胶体是钙钛矿前驱体溶液的重要组成部分，对钙钛矿的成膜质量有重大影响。
近日，南开大学李红时副教授等人在Science China Materials发表研究论文，探索了两种不同类型前驱体的胶体成分：原料单体混合溶解（MMD）和预合成的钙钛矿单晶再溶解（SCR）。
本文要点
1) 发现了一种新的溶解化学平衡机制，即从混合单体到3C立方相（α相）的转变涉及一个可逆的转变过程。2) MMD的方法产生了多聚Pb-I溶剂化胶束，而SCR方法产生的则是六方卤化铅基的钙钛矿胶体，这种胶体组成的差别显著影响了成膜质量。3) 六方相胶体是有利的成核位点，可促进形成晶粒更大、相更均匀、缺陷更少的α相钙钛矿薄膜。这项工作证明了调控胶体成分的重要性，并从理论上深入探讨了以粉末、微晶和单晶等形式重新溶解钙钛矿的有利影响。
Figure 1. (a) XRD pattern of fresh and aged perovskite single crystals. The inset is a photograph of synthesized perovskite single crystals. (b, c) DLS results of the perovskite precursors using MMD (denoted as C-Unfiltered) and synthesized perovskite single crystal (denoted as S-Unfiltered), respectively. The insets represent the distribution of small-sized colloids in the range of a few nanometers in the C-Unfiltered and S-Unfiltered precursors, respectively. (d, e) ICP-OES results of C-Filtered, C-Unfiltered, S-Filtered and S-Unfiltered. (f) 1H NMR spectra of C-Unfiltered and S-Unfiltered perovskite precursors aged for 5 days.Figure 2. (a) Formation energies of the five surfaces (2H100, 2H101, 4H100, 4H101, and 3C100) in DMSO/DMF solvent mixtures determined by AIMD. (b) Schematic diagram of the chemical equilibrium relationships for dissolution processes and the colloidal composition of precursors of MMD and SCR. (c) The energy schematic diagram of perovskite different phases.Figure 3. (a–d) Top-view SEM images of C-Filtered, C-Unfiltered, S-Filtered and S-Unfiltered films. (e) Steady-state PL spectra and (f) TRPL decays of the C-Unfiltered and S-Unfiltered perovskite films deposited on glass substrate. (h) Steady-state PL spectra and (i) TRPL decays of the C-Unfiltered and S-Unfiltered perovskite films deposited on the FTO/SnO2 substrates. (g) SCLC characteristics of electron-only devices. (j) M-S analysis of the devices. (k) EIS of the C-Filtered, C-Unfiltered, S-Filtered, and S-Unfiltered devices measured with a bias of 1.0 V under dark conditions. The inset presents the equivalent circuit model.![]()
Figure 4. (a) Statistical distributions of PCEs collected from a batch of 100 devices for the C-Filtered, C-Unfiltered, S-Filtered, and S-Unfiltered devices. (b) VOC distribution of perovskite solar cells. (c) J-V curves of the C-Unfiltered and S-Unfiltered devices under both forward and reverse scans. (d) The stabilized power outputs over 150 s of the C-Unfiltered and S-Unfiltered devices were measured at voltages of 0.84 and 0.92 V in the ambient environment, respectively. (e) Dark stability of the unencapsulated devices in the nitrogen environment.Tiantian Lou, Letian Chen, Guichun Yang, Peng Chen, Wenyan Zhao, Hongshi Li, Guoran Li. Unraveling the colloidal composition of perovskite precursor solutions and its impact on film formation. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3189-1
![]()
点击左下角“阅读原文”，阅读以上文章PDF原文
![]()
