Junfeng Han

Electrodeposited CZTS solar cells from Reline electrolyte

This work is the first report of using a deep eutectic solvent named Reline as a green electrolyte to electrodeposit CZTS films for photovoltaic applications. This is successfully achieved by co-electrodepositing Cu–Zn–Sn precursor thin films in Reline and sulfurizing the Cu–Zn–Sn precursors in a mixture of H2S and N2 at 550 °C for 1 h. The CZTS films are uniform and compact on a microscopic scale, which translates to a benign photoresponse of the CZTS solar cell. Photovoltaic devices were prepared from the films and an efficiency of 3.87% has been achieved. The device performance indicates that Reline is a viable green solvent for the electrodeposition of CZTS thin film solar cells in a low cost way.

Earth-abundant and low-cost CZTS solar cell on flexible molybdenum foil

Flexible Cu2ZnSnS4 (CZTS) solar cell absorbers were prepared by sulfurizing Cu–Zn–Sn precursors which were co-electrodeposited on Mo-coated molybdenum foil in a one-step process. A photovoltaic device with 3.82% conversion efficiency based on the illumination area of 0.35 cm2 was attained, which is the first efficiency report of flexible CZTS-based solar cells on molybdenum foil.

Controllable growth of two-dimensional WSe2 using salt as co-solvent

Various structures of two-dimensional (2D) WSe2 were controllably grown in a chemical vapor deposition (CVD) system. Using salt as the co-solvent and surfactant, we were able to grow monolayer single-crystalline WSe2 flakes with lateral size of up to 215 μm and monolayer polycrystalline WSe2 with lateral size of a few millimeters on amorphous SiO2 substrates. Optical microscopy, atomic force microscopy, Raman spectra, photoluminescence spectra and X-ray photoelectron spectra measurements disclosed high quality of as-grown 2D WSe2. Moreover, multilayer WSe2 flakes with spiral dislocations and uniform size were also achieved. Our study demonstrates that the salt-assisted CVD technique can be applied for the controllable synthesis of 2D transition metal dichalcogenides with various structures and morphologies, paving the way for developing novel catalysts and electronic devices.