Ternary organic photovoltaic using long wavelength light absorption polymer as guest donor with enhance photovoltaic performance

Abstract

Ternary organic photovoltaics (OPVs) are fabricated by PTQ10 as donor materials, Y6 as an acceptor, and PTB7-Th as a guest donor. The lowest unoccupied molecular orbital (LUMO) energy levels of PTB7-Th are deeper than those of PTQ10, and a cascade of LUMO energy levels is formed among the different device materials. The PTQ10:Y6 binary OPVs show an open-circuit voltage (VOC) of 0.870 V, which is relatively higher than that obtained for the ternary OPVs. The decrease in the VOC of the ternary OPVs is mainly ascribed to an upshift in the HOMO energy levels of the blend donor and a narrow energy bandgap. The short-circuit current density (JSC) for the ternary OPVs can be increased from 25.07 mA cm−2 to 26.60 mA cm−2 with a PTB7-Th content of up to 15 wt%, which is mainly attributed to efficient photon harvesting and reduced charge recombination. Therefore, these results indicate that JSC and PCE can be significantly enhanced by the incorporation of PTB7-Th into PTQ10:Y6 binary films despite a significant decrease in VOC.