金属卤化物钙钛矿晶格结构中卤素肖特基缺陷的存在降低了离子迁移的活化能。本研究以MAPbI3为钙钛矿原型，研究卤素离子相关点缺陷的来源和抑制机制。我们的研究结果表明，原始配位溶剂的使用使得MA+-PbI3-或MAI-PbI2空间分离是导致碘肖特基缺陷的主要原因。该工作通过引入氧化配位溶剂（o-NMP），使得MAI和PbI2可以在溶液中进行可逆的原位氧化还原反应。
因此，观察到增强的功率转换效率（PCE）， MAPbI3基钙钛矿太阳能电池（PSCs）超过22%，使用室温叶片涂层方法制造的FAMA混合器件接近24%。在相应的钙钛矿体系下，这两个效率值都是用类似的处理技术实现的最高记录。此外，PSCs在阳光照射、外部电场和水分渗透方面表现出更好的稳定性。
Fig. 1. Fabrication of o-NMP and chemical evolution in PPS. (a) 1H NMR spectra of NMP and o-NMP. (b) Absorption spectra of 2-ME-PPS and o-NMP-PPS, and I2 dissolved in 2-ME as a reference. (c) The change in the pH values of different PPSs before and after the single crystal growth. (d-f) Top view of MHP single crystals in 2-ME-PPS (d), NMP-PPS(e) and o-NMP-PPS (f) via reverse temperature crystallization method at 80 °C, where an LED light was placed underneath for better observation.
Fig. 2. The role of coordinating solvent in regulation of the PbI2-MAI segregation in MHP. In-situ XRD of MHP in the solutions with (a) 2-ME, (c) 2-ME/DMSO, (e)2-ME/NMP and (g) 2-ME/o-NMP as the solvent, respectively. The triangles represent the intermediate phase, the circles represent MHP and the diamond shape represents MA2Pb3I8·2DMSO. The characteristic crystallization morphologies of MHP in the solutions with (b) 2-ME, (d) 2-ME/DMSO, (f) 2-ME/NMP and (h) 2-ME/o-NMP as the solvent, during the progression of crystallization. The scale bar is 20 μm in b and d, and 4 μm in f and h.
Fig. 3.(a,d) 5×5 μm2 topographical morphologies and (b, e) CPD maps of MHP films characterized by KPFM. (c, f) CPD profiles for D-MHP and o-MHP along the dashed lines in (b, e). The violet lines derived from (a, d) are used to distinguish the location of GBs. (g,j) Topographical morphologies and (h, k) current intensity distributions of MHP films characterized by C-AFM. (i, l) Line scans of the current for D-MHP and o-MHP as respectively marked in (h, k); the corresponding height profiles (violet lines) are also provided.
Fig. 4.Fluorescence intensity evolution of D-MHP and o-NMP under light soaking for (a, d) 0 min and (b, e) 10 min, respectively. Fluorescence intensity distribution of (c) D-MHP and (f) o-MHP after 10 minutes following the cessation of light, respectively.
Fig. 5.(a) The current density–voltage (J–V) scanning of champion D- and o-PSCs with an active area of 0.09 cm−2. (b) Dark J–V curves of PSCs. (c) EL measurement for the PV devices working as the light-emitting diode (LED). Inset: Digital picture of o-PSC under a constant voltage of 1.5 V. (d) Nyquist plots of EIS spectra for D- and o-PSCs. (e) J-T curves of D- and o-PSCs under periodic illumination. (f) J–V curves of FA0.7MA0.3PbI3-based PSCs with a record efficiency of 23.94%.
Fig. 6.Consecutive forward J-V scans of (a) D-PSCs and (b) o-PSCs. The inset shows the PCE evolution of the photovoltaic (PV) devices derived from the corresponding J-V curves. In-situ observation of the PL evolution in (c) D-MHP and (d) o-MHP under a lateral bias of 5 V. (e) Stability of unencapsulated devices in humid air (T=25±2°C, relative humidity (RH)=40±10%), and (f) at 85°C in a nitrogen atmosphere.
Xudong Liu, Xuewei Jiao, Song Yin, Nasir Ali, MingxuanLiu, Bingshun Xu, Shaopeng Yang, Weiguang Kong. Oxidization Strategy of Coordinating Solvents Mitigates Composition Segregation in Perovskite. nanoen.2025.110717
https://doi.org/10.1016/j.nanoen.2025.110717
