Proceedings of nanoGe September Meeting 2017 (NFM17)
Publication date: 20th June 2016
Lead-based halide perovskite quantum dots (LPQDs) have attracted great attention in recent years as light harvesting materials for photoelectric applications because of their unique properties, such as direct band gap, large absorption coefficient, high carrier mobility, and tunable band structure. However, the large surface-to-volume ratio makes them tend to aggregate and introduces surface defects, leading to fast electron-hole recombination. The flexible two-dimensional (2D) feature of graphene and its superior electrical properties make it a promising candidate for acting as the loading platform of LPQDs to prevent undesired aggregation, thus work as effective carriers extractor and transporter. Combining the advantages of graphene and well-developed Si technologies is a good choice to expand its applications. The first graphene-Si heterojunction solar cell was demonstrated in 2010, in which graphene functioned as a transparent window layer and a carrier transporting layer while Si played a role in photogeneration. In the past years, its power conversion efficiency has been improved from 1.7% to 15.6% with delicate electrical and optical designs, including doping of graphene, interface passivation and anti-reflection coating.
Properly integrating nanostructures might promote light adsorption and the efficiency is expected to be further improved. Graphene sensitized with colloidal PbS, ZnO and LPQDs light harvesters was developed for efficient photodetection. Integrating LPQDs into the graphene-Si heterostructure may introduce some new characteristics or lead to improvements in device performance. Their size, composition, morphology and surface ligands are tailorable to optimize the charge transfer between quantum dots and the interactions with graphene. Liquid phase synthesis also offers great flexibility in device structure design with relatively facile techniques.