Rational design of eco-friendly Mn-doped nonstoichiometric CuInSe/ZnSe core/shell quantum dots for boosted photoelectrochemical efficiency
Rui Wang, Xin Tong, Zhihang Long, Ali Imran Channa, Hongyang Zhao, Xin Li, Mengke Cai, Yimin You, Xuping Sun, Zhiming Wang
Abstract
Colloidal core/shell quantum dots (QDs) with environment-friendly feature and controllable optoelectronic properties are promising building blocks in emerging solar technologies. In this work, we rationally design and tailor the eco-friendly CuInSe (CISe)/ZnSe core/shell QDs by Mn doping and stoichiometric optimization (i.e., molar ratios of Cu/In). It is demonstrated that Mn doping in In-rich CISe/ZnSe core/shell QDs can effectively engineer the charge kinetics inside the QDs, enabling efficient photogenerated electrons transfer into the shell for retarded charge recombination. As a result, a solar-driven photoelectrochemical (PEC) device fabricated using the optimized Mn-doped In-rich CISe/ZnSe core/shell QDs (Cu/In ratio of 1/2) exhibits improved charge extraction and injection, showing a ∼ 3.5-fold higher photocurrent density than that of the pristine CISe/ZnSe core/shell QDs under 1 sun AM 1.5G illumination. The findings indicate that transition metal doping in “green” nonstoichiometric core/shell QDs may offer a new strategy for achieving high-efficiency solar energy conversion applications.