Research Assistant, Supervisor: Assoc. Prof. Qin Donghuan, Research Institute of Optoelectronic Materials and Devices
Objective: Aimed to promote the performance of CdTe-based nanocrystal (NC) solar cells through rationally controlled doping (phosphine and copper), alloy engineering, and effective surface/interface treatments; explored strategies for band structure modulation and back contact interface optimization.
Materials Synthesis: Prepared CdSe, CdTe, CdSeₓTe₁₋ₓ alloy NCs via heat injection by varying precursor ratios; synthesized sodium tetradecanoate, cadmium myristate, CdSe and CdTe NCs by solvothermal methods; obtained peony- and black-colored NC solutions.
Simulation: Performed computational modeling of CdTe NCs; explored Cu-doped CdTe NCs and triphenylphosphine ligand exchange; optimized structures with the ORCA (B97-3c) and CP2K (PBE) to calculate HOMO–LUMO gaps and plotted DOS diagrams.
Device Characterization: Deposited NC thin films by layer-by-layer annealing, fabricated multilayered ITO/ZnO/CdSe/CdTe NC solar cells, and deposited Au back contacts. Devices were characterized using solar simulators, UV–Vis–NIR spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, impedance analyzer, and transient photovoltage spectrum.
Outcome: Achieved improved photovoltaic performance of solution-processed CdTe NC solar cells, with phosphine-doped devices showing a PCE increase to 5.41% (41% higher than undoped). Alloy engineering and computationally studied Cu substitution further clarified the mechanism of enhanced energy level alignment and interfacial charge transfer. The alloy engineering project was rated as an excellent undergraduate graduation thesis.