Department of Chemistry, Laboratory of Advanced Materials, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University , 2205 Songhu Road, Shanghai 200438, China.
State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Department of Physics, Collaborative Innovation Center of Advanced Microstructures, Fudan University , 220 Handan Road, Shanghai 200433, China.
J Am Chem Soc. 2016 Jul 13;138(27):8581-7. doi: 10.1021/jacs.6b04519. Epub 2016 Jul 1.
To improve the interfacial charge transfer that is crucial to the performance of perovskite solar cells, the interface engineering in a device should be rationally designed. Here we have developed an interface engineering method to tune the photovoltaic performance of planar-heterojunction perovskite solar cells by incorporating MAPbBr3-xIx (MA = CH3NH3) quantum dots (QDs) between the MAPbI3 perovskite film and the hole-transporting material (HTM) layer. By adjustment of the Br:I ratio, the as-synthesized MAPbBr3-xIx QDs show tunable fluorescence and band edge positions. When the valence band (VB) edge of MAPbBr3-xIx QDs is located below that of the MAPbI3 perovskite, the hole transfer from the MAPbI3 perovskite film to the HTM layer is hindered, and hence, the power conversion efficiency decreases. In contrast, when the VB edge of MAPbBr3-xIx QDs is located between the VB edge of the MAPbI3 perovskite film and the highest occupied molecular orbital of the HTM layer, the hole transfer from the MAPbI3 perovskite film to the HTM layer is well-facilitated, resulting in significant improvements in the fill factor, short-circuit photocurrent, and power conversion efficiency.
为了改善钙钛矿太阳能电池性能至关重要的界面电荷转移，器件中的界面工程应进行合理设计。在这里，我们通过在 MAPbI3 钙钛矿薄膜和空穴传输材料（HTM）层之间引入 MAPbBr3-xIx（MA = CH3NH3）量子点（QD），开发了一种界面工程方法来调节平面异质结钙钛矿太阳能电池的光伏性能。通过调整 Br:I 比，合成的 MAPbBr3-xIx QD 表现出可调谐的荧光和能带边缘位置。当 MAPbBr3-xIx QD 的价带（VB）边缘低于 MAPbI3 钙钛矿时，MAPbI3 钙钛矿薄膜到 HTM 层的空穴转移受到阻碍，因此，功率转换效率降低。相比之下，当 MAPbBr3-xIx QD 的 VB 边缘位于 MAPbI3 钙钛矿薄膜的 VB 边缘和 HTM 层的最高占据分子轨道之间时，MAPbI3 钙钛矿薄膜到 HTM 层的空穴转移得到很好的促进，从而显著提高填充因子、短路光电流和功率转换效率。
