Efficient perylene-diimides-based nonfullerene acceptors with triazine cores synthesized via a simple nucleophilic substitution reaction

Noble-metal catalyst is widely-used to synthesize high-efficiency photovoltaic materials. However, expensive catalysts are difficult to remove and the residual catalysts have deleterious effects on photovoltaic performance. In this study, novel efficient non-fullerene acceptors (NFAs) are synthesized via simple nucleophilic substitution without any noble-metal catalyst. An impressive power conversion efficiency (PCE) of 8.91% is obtained using a single triazine-cored NFA, called NAQ-3. To the best of our knowledge, this is the highest PCE for NFAs synthesized via simple nucleophilic substitution or noble-metal-free reactions. Moreover, a delicate four-armed NFA with a bitriazine core, called NAQ-4, is synthesized as an extension example of this synthesis method. Furthermore, the absorption spectra and energy levels of NAQ-3 and NAQ-4 are compared, and the photovoltaic performance, dissociation process and underlying recombination mechanisms of NAQ-3- and NAQ-4-based organic solar cells are analyzed to determine the structure-performance relationship. The results indicate a successful example of high-performance NFAs synthesized via nucleophilic substitution reactions.