Enhanced performance of perovskite solar cells by the incorporation of the luminescent small molecule DBP: perovskite absorption spectrum modification and interface engineering

Abstract

The interfacial defect states between the active layer and the charge transport layer in perovskite solar cells (PSCs) are one of the main channels of energy loss, which can result in carrier recombination loss and then limit the efficiency and stability of devices. In this study, the luminescent organic small molecule material tetraphenyldibenzoperiflanthene (DBP) was inserted between CH₃NH₃PbI₃ perovskite and the electron transport layer PCBM as an interface modification layer. As a result, DBP-based PSCs attained the average power conversion efficiency (PCE) of 15.61%, obviously higher than 14.26% of the reference device. The enhanced PCE was attributed to the multifunctional synergistic effect of DBP. DBP not only behaves as an efficient interface modification layer to passivate the perovskite defects and improve the energy level alignment, thereby reducing carrier recombination losses at the interface, but also plays a role as a CH₃NH₃PbI₃ absorption spectrum modification layer by Föster energy transfer and thus enhances the light absorption of the CH₃NH₃PbI₃ layer in the near-infrared region. Moreover, the hydrophobic and passivation effects of DBP improve the air-, thermal- and photo-stability of the PSCs. This study demonstrates the use of multifunctional organic luminescent molecules as an interfacial engineering material is a highly useful and facile method for improving the performance of planar perovskite solar cells.