Compromising Charge Generation and Recombination with Asymmetric Molecule for High-Performance Binary Organic Photovoltaics with Over 18% Certified Efficiency

Balancing the charge generation and recombination constitutes a major challenge to break the current limit of organic photovoltaics (OPVs). To address this issue, an asymmetric non-fullerene acceptor, namely the AC9, is developed and high-performance OPV with a champion efficiency of 18.43% (18.1% certified) is demonstrated. This represents the record value among binary OPVs. Comprehensive analysis on exciton dissociation, charge collection, carrier transport, and recombination has been carried out, unveiling that the improved device performance of asymmetric AC9-based OPVs is originated from a better compromise between charge generation and non-radiative charge recombination, compared with the corresponding symmetric ones. This work provides a high-performing molecule and paves the way for high-performance OPVs through asymmetric molecular design.

Automated summary

Balancing charge generation and recombination is a major challenge in breaking the limitations of organic photovoltaics. Researchers have developed an asymmetric non-fullerene acceptor called AC9, demonstrating a high-performance OPV with a champion efficiency of 18.43%. Comprehensive analysis shows that the improved device performance of AC9-based OPVs is due to a better compromise between charge generation and non-radiative charge recombination compared to symmetric acceptors.