Two Novel Small Molecule Donors and the Applications in Bulk-Heterojunction Solar Cells

Abstract

Two novel small molecules <b>DTRDTQX</b> and <b>DTIDTQX</b>, based on ditolylaminothienyl group as donor moiety and quinoxaline as middle acceptor moiety with different terminal acceptor groups were synthesized and characterized in this work. In order to study the photovoltaic properties of <b>DTRDTQX</b> and <b>DTIDTQX</b>, bulk-heterojunction solar cells with the configuration of FTO/c-TiO₂/<b>DTRDTQX</b>(or <b>DTIDTQX</b>):C₇₀/MoO₃/Ag were fabricated, in which <b>DTRDTQX</b> and <b>DTIDTQX</b> acted as the donors and neat C₇₀ as the acceptor. When the weight ratio of <b>DTRDTQX</b>:C₇₀ reached 1:2 and the active layer was annealed at 100°C, the optimal device was realized with the power conversion efficiency (PCE) of 1.44%. As to <b>DTIDTQX</b>:C₇₀-based devices, the highest PCE of 1.70% was achieved with the optimal blend ratio (<b>DTIDTQX</b>:C₇₀ = 1:2) and 100°C thermal annealing treatment. All the experimental data indicated that <b>DTRDTQX</b> and <b>DTIDTQX</b> could be employed as potential donor candidates for organic solar cell applications.