Regulating Thiol Ligands of p-Type Colloidal Quantum Dots for Efficient Infrared Solar Cells
Jingxuan Chen, Siyu Zheng, Donglin Jia, Wanlu Liu, Aneta Andruszkiewicz, Chaochao Qin, Mei Yu, Jianhua Liu, Erik M. J. Johansson, Xiaoliang Zhang
Abstract
The p-type semiconducting colloidal quantum dot (CQD), working as a hole conductor in CQD solar cells (CQDSCs), is critical for charge carrier extraction and therefore, to large extent, determines the device’s photovoltaic performance. However, during the preparation of a p-type CQD solid film on the top of an n-type CQD solid film, forming a p-n heterojunction within the CQDSCs, the optoelectronic properties of the underlayered n-type CQD solid film are significantly affected by conventional 1,2-ethanedithiol (EDT) ligands due to its high reactivity. Herein, a series of thiol ligands are comprehensively studied for p-type CQDs, which suggests that, by finely controlling the interaction between the CQDs and thiol ligands during the preparation of p-type CQD solid films, the n-type CQD solid films can be well protected and avoid destruction induced by thiol ligands. The p-type CQD solid film with 4-aminobenzenethiol (ABT) passivating the CQD surface exhibits better optoelectronic properties than the conventional p-type EDT-based CQD solid films, resulting in an improved photovoltaic performance in CQDSCs.