rGO@CuSCN bilayer as composite back contact for highly efficient CdTe thin-film solar cells.

Highly efficient CdTe solar cells were fabricated by introducing rGO@CuSCN as a composite back contact. The rGO@CuSCN was prepared by convenient solution-processed method. As a Cu-doping source and electron reflection layer, CuSCN could facilitate to dope CdTe and decrease the carrier recombination on the back surface of CdTe. The rGO, as a hole transport layer, could suppress unfavorable over-diffusion of Cu and improve hole collection and transport. The results show the obvious reduction of back barrier height and decrease of the dark current density in the devices with rGO@CuSCN back contact. Using facile coating method and optimal thermal annealing for the preparation of rGO@CuSCN composite back contact, CdTe solar cell presented greatly enhanced photovoltaic performance (E ff : 16.84%, V oc : 841 mV, J sc : 26.83 mA/cm2, FF: 74.6%). • Solution-processed CuSCN and rGO composite back contact was used in CdS/CdTe solar cells. • CuSCN provides Cu-source for CdTe doping and reflects electron as a carrier selective transport layer in CdTe solar cells. • rGO improves the transfer and collection of the carriers, and inhibits the excessive diffusion of copper. • rGO@CuSCN effectively decreases the back barrier and carrier recombination in CdTe solar cells. [ABSTRACT FROM AUTHOR]