Self‐Assembly Metal Chelate as Ultraviolet Filterable Interface Layer for Efficient Organic Solar Cells
Runnan Yu, Rui Shi, Hao Liu, Guangzheng Wu, Zongwen Ma, Huaizhi Gao, Zhang-Wei He, Zhan’ao Tan
Abstract
Abstract Interface engineering plays a vital role in the further improvement of efficiency and stability for organic solar cells (OSCs). Herein, a self‐assembly metal chelate based on hafnium and a designed ligand, N‐(4‐(3‐oxobutanoyl)phenyl)acetamide (ACBN) is applied as both interfacial modification layer and UV‐light filter in OSCs. The strong hydrogen‐bond induced intermolecular interaction enables Hf(ACBN) 4 with the prerequisite of adequate solvent resistance to work as an electron transport layer (ETL) in the inverted OSCs. The self‐assembly behavior of Hf(ACBN) 4 on the SnO 2 film surface via constructing compact coordination structure has been verified via systematic theory calculations. In addition to optimizing the energy level alignment, the Hf(ACBN) 4 modification effectively passivates the surface defect of SnO 2 films for less surface charge recombination and a more efficient charge collection process. Thus, the OSCs with Hf(ACBN) 4 layer yield a maximum PCE of 18.1%, better than that based on the bare SnO 2 layer. Moreover, beneficial from the reduced oxygen vacancies via coordination effect and the UV‐light filter function of Hf(ACBN) 4 , the OSCs based on SnO 2 / Hf(ACBN) 4 composite ETL exhibit preferable stabilities under UV‐light irradiation or continuous operational conditions.