In-situ hydrothermal growth of MoS2 absorber layer for planar heterojunction solar cells

• First development of MoS 2 film as the absorber layer material of planar solar cells. • CdS film provides a robust template for the quasi-epitaxial growth of MoS 2 layer. • SCAPS simulation provides the guidance of optimization of CdS/MoS 2 heterojunction . MoS 2 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 MoS 2 with (0 0 2) preferred orientation by enjoying the analogical hexagonal structures and the shared sulfur atoms, resulting in a benign interface of CdS/MoS 2 . Then a device with ITO/TiO 2 /CdS/MoS 2 /Carbon-Ag structure is assembled after coating carbon-Ag electrode. The effects of the growth characteristics, morphology changes and optical properties of MoS 2 on the device performance are studied systematically. Finally, a primary efficiency of 0.12% is achieved using a P-type MoS 2 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 × 10 15 cm −3 ) and defect density (<5 × 10 15 cm −3 ) of MoS 2 film as well as inserting a hole transport layer, the efficiency of MoS 2 planar device can be enhanced to 10.77%. This work provides an in-situ growth route for constructing a CdS/MoS 2 planar heterojunction as a potential candidate for the low-cost solar cells.