The expensive and unstable organic hole transport layer (HTL) is one of the crucial problems that hampers the wide application of perovskite solar cells. Here, an MAPbI₃-(BA)₂(MA)_n−1Pb_nI_3n+1 3D-2D perovskite-perovskite planar heterojunction (PPPH) through a facile BAI and MAPbI₃ interfacial ion exchange process was conducted. A graded band structure was formed for efficient charge separation, and the conductivity of the 2D perovskite can be tuned by extrinsic FA incorporation, which provides effective conducting channels for holes, making the modified 2D perovskite layer a promising and stable HTL. Optimized solar cells based on 3D-2D PPPH showed a champion power conversion efficiency (PCE) of 13.15% initially and 16.13% after thermal aging, and could maintain 71% output for 50 days under 65% humidity, and 74% for 30 days under 85°C, without encapsulation. This work points to realize low cost and ambient compatible PPPH solar cells with high PCE and robust stability.

昂贵且不稳定的有机空穴传输层（HTL）是阻碍钙钛矿太阳能电池广泛应用的关键问题之一。在此，通过简单的BAI和MAPbI ₃形成MAPbI _3-（BA）₂（MA）_n-1 Pb _n I _{3 n + 1} 3D-2D钙钛矿-钙钛矿平面异质结（PPPH）进行了界面离子交换过程。形成梯度带结构以有效分离电荷，并且可以通过非固有FA掺入来调节2D钙钛矿的电导率，这为空穴提供了有效的导电通道，使改性的2D钙钛矿层成为有前途且稳定的HTL。基于3D-2D PPPH的优化太阳能电池的初始功率转换效率（PCE）最初为13.15％，热老化后为16.13％，并且在65％的湿度下可保持71％的输出功率50天，在65％的湿度下可保持74％的功率30天85°C，无封装。这项工作旨在实现具有高PCE和稳定稳定性的低成本和环境兼容的PPPH太阳能电池。