Research Projects

A growing demand for sustainable energy and advanced optoelectronic devices worldwide has led to intensive study of materials capable of efficiently converting light into electricity. Silicon had been the leading material in the field due to its abundance and well-established processing, but it is limited due to its brittleness, ultra-high purity (99.999%) is needed, and it is not compatible for low-cost or flexible applications. These limitations impose a major obstacle in realizing advanced lightweight and mechanically flexible optoelectronic devices. To address these challenges, in this proposal, we present a novel design approach based on two-dimensional (2D) van der Waals (vdW) heterostructures. These 2D materials possess peculiar properties, including mechanical flexibility, tunable bandgaps, strong light-matter interaction, and stackability with no limitation of lattice matching. These make vdW heterostructures promising to build devices that are flexible and light as well as efficient and stable. Scientific Objective: Designing and Synthesizing Ruddlesden-Popper perovskites (RPP) and Indium selenide (InSe) single crystals. Stacking of new vdW-heterostructures of RPP/InSe with defined interface engineering for an improved charge separation. Fabrication of flexible and rigid photodetector and solar cell devices. Detailed investigation under both mechanical strain and light to assess stability, efficiency and flexibility. Hypothesis: In this work, we hypothesis that well-designed vdW heterostructures-featuring optimal band alignment, strong interlayer coupling, and reduced defect at the interface will allow for a high-performance optoelectronic device that possesses both excellent charge transport and mechanical properties. Thinning the absorber layer and tuning the heterointerfaces are likely the two main design parameters to improve the performance and the flexibility simultaneously. Impact: The successful execution of this project could make important contribution to the development of flexible and low-cost optoelectronics. It should lead to profound understanding for the interlayer interaction, charge transport kinetics, and the device stability of 2D devices. Most importantly, this work offers an engineering avenue for high-performance vdW materials in wearable electronics, and portable energy harvester and the next-generation sensing applications.