Preparation and band structure study of PEDOT-MoS2/n-Si heterojunction

Poly (3,4-ethylenedioxythiophene): Poly (styrenesulfonate) (PEDOT: PSS)/Silicon (Si) hybrid heterojunctions are commonly employed in the manufacturing of optoelectronic devices such as solar cells and detectors because of their low cost. However, the conduction band levels of PEDOT: PSS and Si are similar, resulting in an excessively low electron barrier. This makes it easy for electrons in Si across the interface into the PEDOT: PSS layer, leading to an increase in recombination current and a decrease in the device performance. This work initiates with a comparative analysis of the optoelectronic characteristics between MoS2 quantum dots and nanosheets. Then, MoS2 quantum dots with a wider bandgap and higher conduction band level are selected to be doped into PEDOT: PSS to prepare PEDOT-MoS2 films, and the characteristics of the films are analyzed. Finally, the band structure of the PEDOT-MoS2/n-Si heterojunction is investigated. The results show that the incorporation of MoS2 quantum dots can enhance the conductivity and conduction band level of the PEDOT: PSS film, simultaneously increase the work function of the film, and reduce the divergence between the Fermi level and the valence band level. Through simultaneously enhancing the blocking ability of PEDOT: PSS films and improving the built-in electric field of heterojunctions, the recombination current in the film and the interface is reduced, facilitating the transfer and transport of hole carriers. This study proposes a new approach for improving the quality of PEDOT: PSS/Si heterojunctions.