A High Mobility Conjugated Polymer Enables Air and Thermally Stable CsPbI2Br Perovskite Solar Cells with an Efficiency Exceeding 15%. Issue 9 (31st July 2019) - Zhao, Huan
Abstract: Inorganic cesium lead halide perovskite solar cells (PSCs), such as CsPbI2 Br, have made a striking breakthrough with a power conversion efficiency of over 16%. However, CsPbI2 Br is known to be very sensitive to moisture, and the intrinsic long‐term stability of CsPbI2 Br film remains a critical challenge. Interface engineering has been proven to be an effective way for solving the instability‐to‐moisture issue and enhancing the performance of inorganic–organic hybrid PSCs, while there are a few reports on interface engineering for inorganic PSCs. Here, a conjugated polymer, poly( N ‐alkyldiketopyrrolo‐pyrrole dithienylthieno[3, 2‐b]thio‐phene) (DPP‐DTT), with high mobility is introduced as a novel interface passivation for CsPbI2 Br PSCs, which can significantly reduce nonradiative recombination in perovskite, leading to significant enhancement in both efficiency and stability of CsPbI2 Br PSCs. Through DPP‐DTT passivation, a champion efficiency of 15.14% is obtained in CsPbI2 Br PSCs. Moreover, the Lewis base DPP‐DTT can serve as an ultrahydrophobic agent to hold the photovoltaic performance of CsPbI2 Br PSCs under ambient environment with humidity or thermal stress. These results provide a simple while highly effective route of fabricating the highly efficient and stable inorganic PSCs. Abstract : A high mobility Lewis base polymer, poly( N ‐alkyldiketopyrrolo‐pyrrole dithienylthieno[3, 2‐b]thio‐phene) (DPP‐DTT) is first applied as a multifunctional passivation layer to achieve highly efficient and stable inorganic perovskite solar cells (PSCs). A power conversion efficiency of 15.14% is obtained in the planar CsPbI2 Br PSCs. Moreover, the Lewis base DPP‐DTT can serve as ultrahydrophobic agent to protect the devices from moisture.