Traditional P-i-N perovskite solar cells have achieved high efficiency over 25%, but the device structure is relatively complex, and generally requires expensive low-conductivity p-type organic semiconductors as hole transport materials. As a typical semiconductor, it is very important to realize the bipolar doping of methylamine lead iodine (CH₃NH₃PbI₃) that is the light-absorbing layer of perovskite solar cell. Also, it is significant to develop perovskite cells with new device structure. Here, we chose lithium iodide (LiI) as the dopant and successfully grow p-type Li⁺ doped CH₃NH₃PbI₃ (MAPbI₃:Li) perovskite films with low resistivity (10³ Ω•cm). The temperature-dependent photoluminescence, Hall effect and Kelvin probe force microscope (KPFM) results strongly confirmed that Li⁺ doping promotes the transformation of pristine weak n-type MAPbI₃ to intentionally doped p-type film. Subsequently, the p-type MAPbI₃ film is used as both the light absorption layer and hole transport layer, and form a PN heterojunction with n-type titanium dioxide (TiO₂), which is used as the electron transport layer, to construct the heterostructural perovskite cell with a photoelectric conversion efficiency (PCE) of 10.43%. The electron beam induced current (EBIC) signal also strongly confirms the existence of the PN heterojunction and the new working mechanism of such new solar cells.

传统的PiN钙钛矿太阳能电池已经实现了25%以上的高效率，但器件结构相对复杂，一般需要昂贵的低电导p型有机半导体作为空穴传输材料。作为典型的半导体，实现钙钛矿太阳能电池吸光层甲胺铅碘（CH ₃ NH ₃ PbI ₃）的双极掺杂非常重要。此外，开发具有新器件结构的钙钛矿电池具有重要意义。这里，我们选择了碘化锂（LII）作为掺杂剂，并成功地生长p型锂⁺掺杂CH ₃ NH ₃碘化铅₃（MAPbI ₃:Li) 具有低电阻率 (10 ³ Ω•cm) 的钙钛矿薄膜。温度相关的光致发光、霍尔效应和开尔文探针力显微镜 (KPFM) 结果有力地证实了 Li ⁺掺杂促进了原始弱 n 型 MAPbI ₃向有意掺杂的 p 型薄膜的转变。随后，p型MAPbI ₃薄膜同时作为光吸收层和空穴传输层，并与n型二氧化钛（TiO ₂)，用作电子传输层，构建光电转换效率 (PCE) 为 10.43% 的异质结构钙钛矿电池。电子束感应电流（EBIC）信号也有力地证实了PN异质结的存在以及这种新型太阳能电池的新工作机制。