Co‐Adsorbent Boosting the Performance of Perovskite Solar Cell Based on Hole‐Selective Self‐Assembled Molecules

Abstract The inverted perovskite solar cells based on hole‐selective self‐assembled molecules (SAMs) have been setting new efficiency benchmarks. However, the agglomeration of SAM and lack of defect passivation ability are two critical issues that need to be addressed. It is demonstrated that by blending co‐adsorbent 4‐phosphoricbutyl ammonium iodide (4PBAI) with 4‐(7H‐dibenzo[c,g]carbazole‐7‐yl) phosphonic acid (4PADCB), enhanced homogeneity, conductivity, and better energy levels can be realized for the co‐SAM hole‐selective contact. The ammonium functional group on 4PBAI also can effectively passivate the defects at the buried interface and template high‐quality perovskite growth. Assisted by synergistic top interface modification, the power conversion efficiency of the optimized device reaches 24.96%, which can retain 95% of the initial after 1200 h in ambient for the unencapsulated device. The findings suggest that a well‐designed co‐adsorbent can effectively address the limitations and further enhance the performance of cutting‐edge SAMs.