Defect Passivation by Pyridine-Carbazole Molecules for Efficient and Stable Perovskite Solar Cells
Ganbaatar Tumen‐Ulzii, Morgan Auffray, Dino Klotz, George F. Harrington, Xiankai Chen, Umamahesh Balijapalli, Vediyappan Veeramani, Nozomi Nakamura, Zhao Feng, Kotaro Takekuma, Yuki Fujita, Pangpang Wang, Sunao Yamada, Kaoru Tamada, Munkhbayar Batmunkh, Yu Lin Zhong, Fabrice Mathevet, Hayden Salway, Miguel Anaya, Samuel D. Stranks, Toshinori Matsushima, Chihaya Adachi
Abstract
The defects in the light-harvesting perovskite absorber layer play a key role in limiting power conversion efficiencies (PCEs) and long-term stability of lead halide perovskite solar cells (PSCs). Although organic ammonium halides have been used for defect passivation in high-performance PSCs, the stability issue is still a challenge. Herein, we develop a novel material of pyridine-carbazole (Py-Cz) to passivate defects via coordination bonding. With this passivation, the photoluminescence intensity of perovskite films was increased. In addition, the formation of under-coordinated Pb2+ defects in perovskite films was reduced significantly, enabling high-performance and long-term stable PSCs. Three different sets of PSCs were constructed, namely, without passivation, with phenethylammonium iodide (PEAI) (commonly used for passivation), and with Py-Cz passivation. Remarkably, the PSCs fabricated using the Py-Cz passivation not only achieved PCEs of over 20% but also retained 85% of their initial performances over more than 5000 h. In contrast, the PSCs without or with PEAI passivation degraded quickly during the long-term operational stability test under light illumination. This method opens up a new opportunity to develop highly efficient and operationally stable PSCs.