Tremendously Enhanced Photocurrent Enabled by Triplet-Triplet Annihilation Up-Conversion for High-Performance Perovskite Solar Cells
The limited solar spectra utilization hinders the further amelioration of perovskite solar cells (PVSCs) performance. Up-conversion (UC) process extends the spectral absorption of PVSCs from visible to near-infrared (NIR) range and minimizes the sub-band-gap photon transmission loss. The perovskite-sensitized triplet-triplet annihilation (TTA) from rubrene (Rub) and dibenzotetraphenylperiflanthene (DBP) has shown great potential in UC applications. Herein, TTA UC mechanism is firstly introduced into PVSCs for converting NIR photons to visible photons, which facilitates the obvious improvement of photocurrent. Attributed to TTA UC effect and energy band alignment of Rub:DBP UC layer with perovskite, the MAPbI3 based PVSCs acquire a champion power conversion efficiency (PCE) of 20.18% accompanied by significant enhancements in the short circuit current density (Jsc) and open-circuit voltage (Voc). In addition, the rubrene doping can promote perovskite growth owing to the formation of π-conjugated agglomerates, which serves as the growing sites for perovskite crystallization nuclei. Furthermore, the Rub:DBP-based unencapsulated devices exhibit excellent moisture stability, which maintain more than 80% of the primitive PCE after 14 days’ storage in air condition (50-70% humidity, 25 °C).