Enhanced Organic Photovoltaic Performance through Modulating Vertical Composition Distribution and Promoting Crystallinity of the Photoactive Layer by Diphenyl Sulfide Additives.

To understand the vertical phase separation in the bulk junction active layer of organic photovoltaic devices is essential for controlling the charge transfer behavior and achieving effective charge collection. Here, diphenyl sulfide (DPS) was introduced as a novel additive into the PTB7-Th:PC71BM-based inverted polymer solar cells (PSCs), and the effect of additives on active blend films and photovoltaic characteristics was carefully studied. The results show that DPS could not only modulate the vertical composition distribution but also promote the ordered molecular packing of the photoactive layer, thus effectively improving exciton dissociation, charge transport, and collection, and thus exhibit an excellent power conversion efficiency of 9.7% with an improved fill factor (>70%) after using 3% DPS additive. The results show that the DPS solvent additive can effectively adjust the vertical phase distribution and crystallinity of blend films and improve the photovoltaic performance of the inverted organic photovoltaic devices.