Boosting the Performance of Environmentally Friendly Quantum Dot‐Sensitized Solar Cells over 13% Efficiency by Dual Sensitizers with Cascade Energy Structure

Generally, high light‐harvesting efficiency, electron‐injection efficiency, and charge‐collection efficiency are the prerequisites for high‐efficiency quantum‐dot‐sensitized solar cells (QDSCs). However, it is fairly difficult for a single QD sensitizer to meet these three requirements simultaneously. It is demonstrated that these parameters can be felicitously balanced by a cosensitization strategy through the adoption of environmental‐friendly Zn–Cu–In–Se and Zn–Cu–In–S dual QD sensitizers with cascade energy structure. Experimental results indicate that: i) the combination of the dual QDs can improve the light‐harvesting capability of the cells, especially in the visible light window; ii) the cosensitization approach can facilitate electron injection, benefitting from the cascade energy structure of the two QD sensitizers employed; iii) the charge‐collection efficiency can be remarkably enhanced by the suppressed charge‐recombination process due to the improved QD coverage on TiO 2 . Consequently, this cosensitization strategy delivers a new certified efficiency record of 12.98% for liquid‐junction QDSCs under AM 1.5G 1 sun irradiation. Moreover, the constructed cells exhibit good stability in a high‐humidity environment.