【Angew.Chem.】南昌大学陈义旺、谈利承|26.47%效率与超强稳态追踪：调控晶面生长构筑高稳定性钙钛矿太阳能电池#

(a) Schematic diagram of the interaction between PbI2 and various molecules. (b) Calculated changes in surface energy and ((c) XRD patterns for pristine PbI2 and PbI2 modified with different molecules. (d) and (e) HR-TEM images of PbI2 and PbI2-PhOAaCl films (the FFT patterns corresponding to the marked regions are provided in Figure S6). (f) and (g) 2D GIXRD patterns, (h) and (i) surface SEM, (j) and (k) cross-sectional SEM images, and (l) and (m) XRD patterns at different incident angles of PbI2 and PbI2-PhOAaCl films.#

(a) Conversion process from PbI2 with specific crystallographic facets into α-phase perovskite via reaction with FAI. (b) Calculated Gibbs free energy differences and ((c) enthalpy changes for the reactions between FAI and PbI2 with distinct crystallographic facets. (d) and (e) Focused ion beam transmission electron microscopy (FIB-TEM) images of control and target perovskite films. To elucidate the PbI2-templated perovskite formation pathway and lattice matching behavior, the reaction extent is modulated by reducing cation concentration. (f) and (g) 2D GIXRD patterns and (h) and (i) semi in situ XRD patterns of control and target perovskite films during thermal annealing.#

结合密度功能理论（DFT）模拟与半原位/原位表征，团队深入挖掘了固-液界面的相转变动力学过程。热力学计算表明，FAI与$\text{PbI}_2$（001）晶面反应生成 $\alpha$ 相钙钛矿的吉布斯自由能变（$\Delta G$）为 $-5.444\text{ eV}$，具有最强的热力学驱动力，能有效抑制反应残留物及未转换 $\text{PbI}_2$ 的存在。聚焦离子束透射电镜（FIB-TEM）图像清晰观测到钙钛矿与$\text{PbI}_2$模板之间形成了高度匹配的晶格相干生长界面。半原位XRD与原位吸收光谱则显示，在热退火过程中，目标薄膜能经历更快速且彻底的相转变，直接转化为纯 $\alpha$ 相钙钛矿，而对照组薄膜中则长期残留未反应的 $\text{PbI}_2$ 杂相。

(a) Schematic illustration of coherent crystal plane growth of perovskite on (001) crystal surface of PbI2. (b) and (c) Top-view SEM images of control and target perovskite films (the corresponding cross-sectional SEM images are provided in Figure S24). (d) and (e) Bottom view SEM images, (f) and (g) CLSM PL mappings, and (h) and (i) spatial potential distribution mappings of control and target perovskite films.#

高质量的相干晶面生长赋予了钙钛矿薄膜优异的形貌和电学性能。形貌表征和电荷动力学测试表明，目标钙钛矿薄膜晶粒显著增大、表面更加平整光滑且内部无孔洞缺陷。共聚焦激光扫描荧光显微镜（CLSM）和开尔文探针力显微镜（KPFM）结果显示，目标薄膜展现出更强且更均匀的荧光发射强度，其表面电势大幅提升且分布高度均匀，证实了空间电荷复合的有效抑制和缺陷密度的显著降低。此外，借由 XRD 残余应力分析证实，PhOAaCl 辅助的晶面生长成功释放了薄膜内部的拉伸应变，从根本上增强了钙钛矿晶格的内在稳定性。

(a) J–V curves based on ITO/SnO2/perovskite/spiro-OMeTAD/Au structure, (b) external quantum efficiency (EQE) spectra and integrated photocurrents, (c) steady-state photocurrents and output PCEs at the maximum power point, (d) 1/C2 versus applied voltage plots (Mott–Schottky), (e) dependence of _V_oc on different light intensities, (f) transient photovoltage decay (TPV) curves, (g) dark current measurement, and (h) Nyquist plots of electrochemical impedance spectroscopy (EIS) of control and target devices. (i) Space-charge limited current (SCLC) measurements of hole-only devices.#

优化的薄膜质量最终转化为器件光伏性能与稳定性的全面跃升。电学性能表征显示，基于 $n\text{-}i\text{-}p$ 平面结构的改性电池器件实现了高达 26.47% 的光电转换效率（PCE），其开路电压提升至 $1.185\text{ V}$，填充因子达到 $84.39\%$，且稳态功率输出表现极其平稳。更为亮眼的是器件令人惊叹的耐受性表现：在 85°C 和 85% 相对湿度（RH）的严苛双 85 湿热环境下，目标薄膜历经 1000 小时仍几乎未见分解；在 ISOS-D-3 考核下运行 1000 小时后仍能保持初始效率的 $94\%$。在环境空气中进行持续一太阳光照下的最大功率点（MPP）稳态追踪测试中，未封装的目标器件在运行超过 2500 小时后依然保留了高达 91% 的初始效率，展现出跻身同类工艺制备器件最高梯队的超强光热稳态运行寿命。

(a) and (b) ToF-SIMS depth profiles and (c) ToF-SIMS 3D images of n–i–p devices after aging at 85°C for 1000 h. (d) Optical images, (e) and (f) time-dependent photoluminescence spectra after aging at 85°C and 85% RH for 1000 h, (g) and (h) XRD patterns under 365 nm UV illumination and (i) the comparison of defect formation energies (DFEs) of different defects of control and target perovskite films. (j) PCE stability of unencapsulated devices after aging at 85 °C and 65% RH over 1000 h. (k) MPP tracking of unencapsulated devices under continuous one sun illumination in ambient air over 2500 h (above measurements were performed on devices with the structure of ITO/SnO2/perovskite/spiro-OMeTAD/Ag). (l) Statistical comparison of MPP stability values from the recently reported n–i–p devices fabricated via two-step sequential deposition.#