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MoS2 thin film is deposited on ITO/CdS substrate by in-situ hydrothermal method, which is expected to be a potential absorber material for planar heterojunction solar cell due to its high absorber coefficient and carrier mobility. The CdS buffer layer provides a robust template for the quasi-epitaxial growth of MoS2 with (0 0 2) preferred orientation by enjoying the analogical hexagonal structures and the shared sulfur atoms, resulting in a benign interface of CdS/MoS2. Then a device with ITO/TiO2/CdS/MoS2/Carbon-Ag structure is assembled after coating carbon-Ag electrode. The effects of the growth characteristics, morphology changes and optical properties of MoS2 on the device performance are studied systematically. Finally, a primary efficiency of 0.12% is achieved using a P-type MoS2 absorber with a thickness of 305 nm, exhibiting an outstanding stability. The one-dimensional solar cell capacitance simulator (SCAPS) is further used to reveal the bottleneck of device performance. After optimizing the doping density (1 × 1015 cm−3) and defect density (

In this work, a three-step (sulfurization-selenization-sulfurization) annealing process was designed to optimize the surface constitution of Cu2ZnSn(S, Se)4 (CZTSSe) thin films, which was prepared by oxide nanoparticles-based approach. The devices with the Mo/CZTSSe/CdS/ZnMgO/ZnO:Al/Al structure were fabricated and their performances were studied. The additional post-sulfurization with low toxicity sulfur powder has negligible impact on the structure, morphology and composition of CZTSSe bulk, however, it improves open circuit voltage of device significantly. The open circuit voltage can be increased significantly from 408 mV (without surface sulfurization) to 497 mV (with surface sulfurization). This is benefited from the increase of surficial sulfur content and the broadening of the surface band-gap of the CZTSSe thin film. The result is confirmed by X-ray photoelectron spectroscopy analysis. Such a crucial three-step annealing process promotes the power conversion efficiency from 4.71% (2-step) to 6.37% (3-step), which is the champion efficiency of oxide precursor derived CZTSSe solar cell.

Germanium selenide (GeSe), a IV-VI chalcogenide containing earth-abundant and low-toxic elements, has attracted increasing interest as a potential absorber material for photovoltaics due to its excellent optical and electrical properties. In this work, a simple and effective magnetron sputtering method was proposed to deposite GeSe precursor thin films using GeSe alloy target. Subsequently, the as-deposited samples were post-annealed in vacuum atmosphere. The effects of different annealing temperatures on crystallinity, morphology and phase transformation of the as-prepared films were systematically investigated. It has been revealed that phase-pure and uniform GeSe thin films were obtained through the self-decomposition of slight GeSe2 impurity at 400 °C. Finally, a prototypical FTO/CdS/GeSe/C-Ag solar cell with 220 mV open circuit voltage and 0.05% power conversion efficiency was fabricated, which suggests the potential of sputtering processed GeSe thin film for low cost solar cell.