Ternary Organic Photovoltaic Devices Based on Wide-band Gap Small Molecule Donor Third Component

Ternary strategy is an efficient way for improving the performance of organic solar cell. In this work,a highly crystallized organic small molecular donor(DRDTBT) was designed and synthesized as the third component of ternary organic solar cells. The introduction of a large conjugated unit dithieno [3',2':3,4;2 '',3 '':5,6]benzo [1,2-c][1,2,5]thiadiazole with electron-withdrawing ability deepened the highest occupied molecular orbital level of DRDTBT as well as enhanced the crystallinity of it. When employed DRDTBT as the third component of PM6:BTP-eC9 active layer, the open circuit voltage of the photovoltaic device was strongly improved, furthermore, the morphology of the active layer also was finely tuned. Benefit from the enhanced open circuit voltage and fill factor, the ternary device results in an improved performance than its binary counterpart, giving a high power conversion efficiency of 17.72% with an open circuit voltage of 0.86 V, a short circuit current density of 26.99 mA/cm(2) and a fill factor of 76.34%. This work proves that introducing highly crystallized electron-deficient units into the small molecule donors third component is an effective way to improve the performance of ternary organic solar cells.