PbS-Based Quantum Dot Solar Cells with Engineered pi-Conjugated Polymers Achieve 13% Efficiency

Abstract

While hole extraction is crucial for the external quantum efficiency of conventional n-i-p colloidal quantum dot (CQD) solar cells (CQDSCs), sulfur-passivated p-type CQDs (pCQDs) have been the best hole-transport material (HTM) to date. In this work, we developed organic a-conjugated polymers (pi-CPs) that can achieve substantially improved HTM performance compared with conventional pCQDs. A weakly electron-withdrawing triisopropylsilylethynyl (TIPS) group was employed with a weak donor moiety, benzo[1,2-b:4,5:b']-dithiophene (BDT), in the push-pull structured H-CPs to optimize the optoelectronic properties of the HTM. The CQDSCs using TIPS-containing pi-CPs achieved a PCE (13.03%) substantially higher than those previously reported using pCQD (11.33%) or pi-CPs (11.25%) owing to the improved charge collection efficiency near the photoactive CQD layer/HTM interface. To the best of our knowledge, our CQDSCs using TIPS-based pi-CPs achieved the highest reported PCE among SSE-free CQDSCs.