Boosting the Efficiency of Quantum Dot‐Sensitized Solar Cells Over 17% via Sequential Deposition of Water‐ and Oil‐Soluble Quantum Dots

Abstract High loading of quantum dots (QDs) on TiO 2 photoanode is essential for high power conversion efficiency (PCE) for quantum dot‐sensitized solar cells (QDSCs). However, there remains a large portion (≈60%) of TiO 2 substrate uncovered by QDs, which results in insufficient light harvesting and the undesired charge recombination, consequently suppressing the enhancement of performance in QDSCs. Herein, a convenient and effective method for improving QD loading is proposed, wherein a direct deposition (DA) mode is carried out after a chemical deposition of capping ligand‐induced self‐assembly (CLIS). It is found that the DA compared with CLIS modes leads to different adsorption behaviors and the interactions of QDs with TiO 2 substrate, thus additional QDs can be successfully deposited. The elevated QD loading amount enhances the light‐harvesting capability and effectively inhibits undesired charge recombination at the photoanode/electrolyte interfaces. Consequently, the average PCE is boosted to 16.89% from the pristine 14.95%, and a champion PCE of 17.04% is achieved, which is the new record for liquid‐junction QDSCs.