Multi‐Facet Passivation of Ternary Colloidal Quantum Dot Enabled by Quadruple‐Ligand Ensemble toward Efficient Lead‐Free Optoelectronics
Dong-Eon Kim, Gaeun Cho, Yun Hoo Kim, Ji Hyun Kwon, Yeonwoo Oh, Minjung Yang, Seungin Jee, In Suh Lee, Min‐Jae Si, Yujin Jung, Ho Yeon Yang, Yongnam Ahn, Beomkwan Kim, Changjo Kim, Han Seul Kim, Se‐Woong Baek
Abstract
Abstract Solution‐processed ternary‐compound semiconductor AgBiS 2 colloidal quantum dots (CQDs) are promising light‐absorbing materials owing to their nontoxicity and high absorption coefficient (>10 6 cm −1 ). However, rational strategies to passivate multi‐facet of ternary‐compound CQDs and manufacture stable CQD inks have not yet been proposed. In this paper, a ligand passivation strategy is proposed using a solution‐phase ligand exchange method. A quadruple‐ligand ensemble is employed to demonstrate multifaceted passivation on AgBiS 2 CQDs and a highly stable CQD ink. Density functional theory studies reveal the secondary cation adsorption of silver halide passivation, indicating the synergistic passivation of the ligand ensemble. This yields a low trap density in CQD solids, improving the power conversion efficiency to 8.1% by 53% in CQD solar cells. Furthermore, the proposed device exhibits the fastest response time of 400 ns among all reported AgBiS 2 devices, demonstrating its potential for efficient lead‐free optoelectronics.