Controlling the Optoelectronic Properties of the Non-Fullerene Acceptor Y6 via p-Doping.

Historically, the low dielectric constants in organic semiconductors necessitated the need for a molecular heterojunction to split excitons into charges, limiting the performance of organic photovoltaic devices. Recently, non-fullerene acceptors (NFAs) with relatively high dielectric constants have shown the ability to create charge transfer states, and even the potential for charges, without the need for a heterojunction. Despite this advancement, problems such as charge trapping and recombination still hinder the efficiencies of organic photovoltaic devices. One of the potential strategies to reduce these losses is via p-doping control, which may help to suppress trap-assisted recombination. Understanding how doping of an NFA impacts its optoelectronic properties is key to developing highly efficient bulk-heterojunction and bilayer devices. In this work, we focused on the influence of doping on device operational properties in Y6-based single-component solar cells with different concentrations of p-dopant trityl tetrakis(pentafluorophenyl) borate (TrTPFB). We demonstrate how the addition of TrTPFB in Y6 shows the signs of trap filling, reduces the influence of complex recombination mechanisms, increases the short-circuit current, and improves the overall efficiency of single-component solar cells. The results reveal the potential of using p-doping control of NFAs in heterojunction and bilayer solar cells.