In mesoporous organo-halide perovskite solar cells, the coexistence of tetragonal phase and cubic phase in the perovskite layer is found to result in strained crystal structure at the mesoporous TiO₂ (mp-TiO₂)/perovskite heterointerface. This results in structural defects pinholes, grain boundaries, and interfacial porosity which is detrimental towards photovoltaic performance and device stability. The strain at the interface originates from the lattice mismatch between the mp-TiO₂ nanoparticles (NPs) and perovskite. Here, a transformative approach is demonstrated to realize relaxed and high purity tetragonal phase MAPbI₃ (RP) near the mp-TiO₂ interface region. This approach involves inserting a ~2 nm lattice matched buffer layer of cubic CsPbBr₃ between mp-TiO₂ NPs and MAPbI₃, which serves as a template for epitaxial growth for top MAPbI₃. The solar cell with relaxed MAPbI₃ shows a power conversion efficiency (PCE) of 22.12% with significantly enhanced environmental, light, and thermal stability.

在介孔有机卤化物钙钛矿太阳能电池中，发现钙钛矿层中四方相和立方相的共存会导致介孔TiO ₂（mp-TiO ₂）/钙钛矿异质界面处的晶体结构发生应变。这导致结构缺陷针孔，晶界和界面孔隙度，这对光伏性能和器件稳定性有害。界面处的应变源自mp-TiO ₂纳米颗粒（NPs）和钙钛矿之间的晶格失配。在这里，展示了一种转化方法，可以在mp-TiO ₂附近实现弛豫的高纯度四方相MAPbI ₃（RP）界面区域。该方法涉及在mp-TiO ₂ NP和MAPbI ₃之间插入立方CsPbBr _3的〜2 nm晶格匹配缓冲层，该缓冲层用作顶部MAPbI ₃外延生长的模板。具有松弛的MAPbI ₃的太阳能电池的功率转换效率（PCE）为22.12％，具有显着增强的环境，光和热稳定性。