Novel nonspiro, fluorene‐based, small‐molecule hole transporting materials (HTMs) V1050 and V1061 are designed and synthesized using a facile three‐step synthetic route. The synthesized compounds ...exhibit amorphous nature with a high glass transition temperature, a good solubility, and decent thermal stability. The planar perovskite solar cells (PSCs) employing V1050 generated an excellent power conversion efficiency of 18.3%, which is comparable to 18.9% obtained with the state‐of‐the‐art Spiro‐OMeTAD. Importantly, the devices based on V1050 and V1061 show better stability compared to devices based on Spiro‐OMeTAD when aged without any encapsulation under uncontrolled humidity conditions (relative humidity around 60%) in the dark and under continuous full sun illumination.
Novel, non‐spiro, amorphous hole‐transporting materials (HTMs) (V1050 and V1061) with fluorene fragments are synthesized using a facile three‐step synthetic route. Planar perovskite solar cells with the V1050 HTM exhibited an excellent power conversion efficiency (PCE) of 18.3%. Furthermore, V1050‐ and V1061‐based devices show better stability compared to devices based on Spiro‐OMeTAD.