The influence of MoS$_{2}$ thickness on the efficiency of solar energy conversion in TiO$_{2}$/MoS$_{2}$/P3HT cells

In the era of global energy crisis, more attention is paid to efficient energy harvesting from renewable sources. Solar power is one of those widely utilized, yet the efficiency of devices converting energy needs to be constantly improved. One of the ideas is to create solar cells that benefit from 2D van der Waals structures combined with other materials such as TiO$_{2}$ and conductive polymers. Such hybrid solar cells show higher power conversion compared to non-composite photovoltaic devices. In this work, a TiO$_{2}$/MoS$_{2}$ heterojunction created in the magnetron sputtering process was covered with a P3HT polymer coating. Composite multilayer systems were investigated (TEM, XRD, Raman spectroscopy and TOF-SIMS) to define the composition, optical properties and solar energy conversion potential. The photovoltaic response of the multilayer system was successfully improved by MoS$_{2}$ band gap engineering based on the quantum size effect. Furthermore, TiO$_{2}$/MoS$_{2}$/P3HT revealed enhanced optical properties and improved charge transport performance with reasonable energy band alignment. The photovoltaic efficiency of hybrid cells doubled compared to previously published work and reached 2.7%. Furthermore, the photovoltaic performance of the solar cells based on TiO$_{2}$/MoS$_{2}$/P3HT exhibited an improvement compared to that of the solar cell based on TiO$_{2}$/P3HT or MoS$_{2}$/P3HT.