Dual interfacial modification to improve the performance of CsPbBr₃ perovskite solar cells

Although CsPbBr₃ perovskite solar cells (PSCs) have excellent thermal and humidity stability, the narrow spectral absorption range and severe charge recombination within the CsPbBr₃ film and device interfaces result in a low power conversion efficiency (PCE). In this work, self-synthesized graphene quantum dots (GQDs) and poly(3-hexylthiophene) (P3HT) are introduced to modify the m-TiO₂/CsPbBr₃ and CsPbBr₃/carbon interfaces of CsPbBr₃ PSCs, respectively. It is found that the carrier extraction and transfer are improved enormously after GQDs and P3HT dual modifications, which can be attributed to the passivated trap states, suppressed charge recombination, and reduced the interfacial energy barrier. Ultimately, for the carbon-based CsPbBr₃ PSCs, a champion PCE as high as 9.74% with outstanding short-circuit current density (J_SC) of 9.36 mA cm^-2 and open-circuit voltage (V_OC) of 1.42 V has been achieved, and the device stability has also been improved greatly. Such a strategy contributes to improving the performance of CsPbBr₃ PSCs.