卤化物钙钛矿太阳能电池（PSCs）由于其低成本和出色的光电特性受到了广泛关注。为了提高效率和稳定性，二维/三维（2D/3D）卤化物钙钛矿异质结构被广泛应用于PSCs中。但2D和3D钙钛矿之间的界面缺陷以及2D覆盖层的不均匀覆盖，限制了PSCs的长期稳定性和均匀电荷提取。
基于以上问题，丘龙斌和戚亚冰教授团队等提出了一种在3D钙钛矿表面进行表面平整化的策略。通过气相辅助过程实现均匀的2D/3D钙钛矿异质结构的外延生长。他们使用异丙醇（IPA）和二甲基亚砜（DMSO）的混合溶剂为平整化剂，对3D钙钛矿表面进行重构，以形成均匀的2D覆盖层。在平整化的3D钙钛矿表面，通过气相辅助过程沉积PbI₂，形成均匀的2D/3D钙钛矿异质结构。并通过形成均匀的2D/3D界面，实现均匀电荷提取和界面非辐射复合的抑制。
表面平整化策略显著提高了2D/3D钙钛矿异质结构的均匀性和稳定性，实现了25.97%的稳定功率输出效率。封装后的PSMs在65℃下连续光照1246小时后，效率仍保持96.9%；在ISOS-O-1协议下，862小时后效率保持91.1%。
此研究展示了通过表面平整化策略制备均匀2D/3D钙钛矿异质结构的方法，能显著提高了PSCs的效率和稳定性。通过平整化策略，实现了26.02%的高效率，并在22.8cm²的活性面积PSMs中实现了23.06%的效率。此外封装后的PSMs在长期操作条件下表现出优异的稳定性和耐用性，为大规模钙钛矿光伏技术的商业化应用提供了可能。
Figure 1. Scheme and effect of planarized 3D perovskites. a) Illustration of the benefits of planarized 2D/3D perovskites heterojunction. The surface planarization of 3D perovskites helps form a uniform 2D capping layer and reduce interfacial defects, which can slow down the outward diffusion of the components from perovskite, suppress interfacial nonradiative recombination, and improve the homogeneity of charge extraction. b) Illustration of the surface planarization. The DMSO@IPA can planarize the surface of 3D perovskite. c) Illustration of the growth model of PbI2 deposited on planarized and control 3D perovskites. The planarized 3D perovskite, with a higher surface energy and better lattice matching with PbI2, can form a uniform PbI2 layer. In contrast, the vapor-deposited PbI2 on the surface of the control 3D perovskite is discontinuous. d,e) AFM-IR images of (d) control 3D perovskite and (e) planarized 3D perovskite. f) The surface energy of control and planarized 3D perovskites.
Figure 2. Epitaxy vapor-assisted growth of uniform 2D/3D perovskites. Top surface SEM images of (a) control 3D perovskite with vapor-deposited PbI2 and (b) control 2D/3D perovskite. c) A cross-sectional SEM image of the planarized 2D/3D perovskite. Top surface SEM images of (d) planarized 3D perovskite with vapor-deposited PbI2 and (e) planarized 2D/3D perovskite. f) A cross-sectional SEM image of the planarized 2D/3D perovskite.patterns of (g) the control 2D/3D and (h) the planarized 2D/3D perovskite films. i) Radial intensity profiles averaged over the entire 2D GIWAXS image.
Figure 3. Carrier transport performance of planarization-epitaxial growth uniform 2D/3D perovskite heterojunction. UPS spectra: a) the secondary electron onset region and b) the valence band region for control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D perovskite films. c) Schematic of energy diagram for the control 2D/3D and planarized 2D/3D perovskite. The orange lines denote the surface trap state in control 3D perovskite, and the black arrows denote the nonradiative recombination pathways and the directions of carrier drift. The interface between control 3D and 2D forms a type-I band alignment, whereas the interface between planarized 3D and 2D forms a type-II band alignment. d) Steady-state PL spectra and (e) TRPL decay curves of control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D perovskite films deposited on glass substrates. f) XRD patterns of control 2D/3D and planarized 2D/3D perovskites before and after aging at 100 °C for 120 min
Figure 4. Performance of the PSCs based on the perovskites with a uniform 2D/3D heterojunction by the planarization-epitaxial growth strategy. a)J–V curves of the champion control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D p-i-n PSCs with a bandgap of 1.57 eV. b) J–V curves of the champion planarized 2D/3D p-i-n PSCs with a bandgap of 1.55 eV. c) The stabilized power outputs of the champion planarized 2D/3D PSCs. d)VOC versus light intensity curves of the control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D p-i-n PSCs. e) Nyquist plots of the control 3D, planarized 3D, control 2D/3D and planarized 2D/3D p-i-n PSCs. f) EQEEL versus voltage of the control 3D, planarized 3D, control 2D/3D, and planarized 2D/3D p-i-n PSCs. g) Stability of encapsulated PSCs under ISOS-L-1 protocol (1-sun illumination using LEDs source, ambient condition with RH of 70%). The initial PCEs of the devices based on control 3D, planarized 3D, control 2D/3D and planarized 2D/3D are 22.07%, 22.89%, 23.52%, and 24.57%, respectively. h) Stability of encapsulated PSCs under ISOS-D-3 protocol.
Figure 5. Homogeneous charge extraction in planarized 2D/3D PSMs. a) Optical photo of the planarized 2D/3D PSM. b,c) The photocurrent images of (b) control 2D/3D and (c) planarized 2D/3D PSM. d) J–V curves of the champion control 2D/3D and planarized 2D/3D PSMs with seven subcells connected in series. e) The stabilized power output of the champion planarized 2D/3D PSM. f) PCEAa distribution of the control 2D/3D and planarized 2D/3D PSMs. g) Stability of encapsulated planarized 2D/3D PSM under ISOS-L-3 protocol (1-sun illumination using LEDs source at 65 °C with RH of 70%). The initial PCEAa of planarized 2D/3D PSM is 22.53%. (h) Stability of encapsulated planarized 2D/3D PSM under ISOS-O-1 protocol (The solar module is stored outdoors, and its PCEAa was acquired using a solar simulator every two weeks).
本文来源：DOI: 10.1002/advs.202407380
https://doi.org/10.1002/advs.202407380