Me-4PACz Functionalized MXene for Halide Perovskite Solar Cells.

Interfacial passivation employing 2D Ti3C2 MXenes has proved to be an excellent strategy to optimize band alignment and passivate defects, leading to the reduction of non-radiative recombination in Perovskite Solar Cells (PSCs). Here in, the synthesis and functionalization of Ti3C2 MXene are reported with the [4-(3,6-Dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid molecule (MXene:Me-4PACz), which is proved by XRD and HRTEM-EELS analyses. Its application at the interface between the halide perovskite (HP) and the Spiro-OMeTAD in normal configuration PSCs, results in the enhancement of indoor and outdoor stability. The MXene:Me-4PACz nanomaterial is obtained in the form of nanoneedles, which, applied in complete PSCs, resulted in a power conversion efficiency (PCE) of ≈21.5%, in comparison with the control device with ≈20.1%. The modified device showed a T88 operational stability obtained at 1000 h for ISOS-L-1 and T50 at ≈1000 h for ISOS-O-2. While, all the control devices degraded 55% after 1000 h under ISOS-L and almost 100% after 900 h under ISOS-O-2. Characterization analyses indicate that the efficiency and stability enhancement is due to the improved energy band alignment and charge extraction, to the increased perovskite surface hydrophobicity, and the significant reduction of deep and shallow trap states.