摘要： Triplet acceptors have been developed to construct high performance organic solar cells (OSCs) since the long lifetime and diffusion range of triplet excitons may dissociate into free charges instead of net recombination when the energy levels of triplet states (T1) are close to those of charge transfer states (3CT). The current triplet acceptors were designed by introducing heavy atoms to enhance the intersystem crossing, limiting their applications. Herein, two twisted acceptors without heavy atoms, analogues of Y6, were constructed with large π-conjugated core and D-A structure, proved to be triplet materials, leading to a high performance OSCs. The mechanism of triplet excitons were investigated to show that the twisted and D-A structures result in large spin orbital coupling (SOC) and small energy gap between the singlet and triplet states, and thus efficient intersystem crossing. Moreover, the energy level of T1 is close to 3CT, facilitating the split of triplet exciton to free charges. This contribution provided new insights in working mechanism of triplet excitons in OSCs.