Highly Efficient Quantum‐Dot‐Sensitized Solar Cell Based on Co‐Sensitization of CdS/CdSe

TLDR

The study assembles CdS and CdSe quantum dots sequentially onto a nanocrystalline TiO₂ film to create a co‑sensitized photoelectrode for quantum‑dot‑sensitized solar cells. The TiO₂/CdS/CdSe cascade electrode reorganizes energy levels into a stepwise band‑edge structure that enhances electron injection and hole recovery. The co‑sensitized CdS/CdSe electrode shows complementary light‑harvesting, with performance strongly dependent on the CdS/CdSe order, achieving a 4.22 % energy‑conversion efficiency—higher than previously reported QD‑sensitized cells.

Abstract

Abstract Cadmium sulfide (CdS) and cadmium selenide (CdSe) quantum dots (QDs) are sequentially assembled onto a nanocrystalline TiO 2 film to prepare a CdS/CdSe co‐sensitized photoelectrode for QD‐sensitized solar cell application. The results show that CdS and CdSe QDs have a complementary effect in the light harvest and the performance of a QDs co‐sensitized solar cell is strongly dependent on the order of CdS and CdSe respected to the TiO 2 . In the cascade structure of TiO 2 /CdS/CdSe electrode, the re‐organization of energy levels between CdS and CdSe forms a stepwise structure of band‐edge levels which is advantageous to the electron injection and hole‐recovery of CdS and CdSe QDs. An energy conversion efficiency of 4.22% is achieved using a TiO 2 /CdS/CdSe/ZnS electrode, under the illumination of one sun (AM1.5,100 mW cm −2 ). This efficiency is relatively higher than other QD‐sensitized solar cells previously reported in the literature.