Application of UV-absorbing silver(I) luminescent down shifter for PTB7 organic solar cells for enhanced efficiency and stability

Presented in this work is the application of a new silver(I) complex [Ag(POP)(Bphen)](BF4) (denoted AgPOP) to provide a means for down-shifting incident ultraviolet (UV) light into the visible range for PTB7-based organic solar cells. The synthesis, material, and optical characterisation of the AgPOP with PTB7 are reported. This material was applied to the OPV light-incident surface without the need for a host polymer. The luminescent down shifting layer serves two purposes. Firstly it improves the photocurrent of the OPV, and thus the efficiency through enhancement of the UV spectral response of the device. This is corroborated by external quantum efficiency data showing enhanced performance at UV wavelengths. Secondly, the AgPOP layer reduces the effect of degradation that originates from UV exposure, which leads to enhanced lifetime.