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 TiO2 photoanode is essential for high power conversion efficiency (PCE) for quantum dot-sensitized solar cells (QDSCs). However, there remains a large portion (≈60%) of TiO2 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 TiO2 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.