Simple carbazole derivatives with mono/dimethoxyphenylacrylonitrile substituents as hole‐transporting materials: Performance studies in hybrid perovskite solar cells

Abstract Herein, we report the development of two new low‐cost 9‐(2‐ethylhexyl)‐9H‐carbazoles carrying the mono/dimethoxyphenyl substituted cyanovinylene units symmetrically at 3‐ and 6‐positions of the carbazole core (CZ1‐2), as potential hole‐transporting materials (HTMs) for perovskite solar cell (PSC) application. The current work highlights their structural, photophysical, electrochemical, theoretical, and photoelectrochemical studies, including evaluation of their structure‐property relationships. Evidently, the optical studies showcased their excellent fluorescence ability due to their push‐pull natured structure; their λabs and λemi values were found to be in the order of 410–430 nm and 530–560 nm, respectively, with a bandgap in the range of 2.5–2.6 eV. Further, their theoretical studies, performed by using the DFT simulations clearly revealed in‐depth information on their molecular geometries, FMO, and electronic properties. Finally, new PSCs were fabricated successfully by employing CZ1‐2 as HTMs to evaluate their photovoltaic performances. Their results indicated that the device with CZ1 displayed enhanced PCE of 2.55% (JSC = 7.85 mA/cm2, VOC = 0.79 V and FF = 40%) than the cell with CZ2 (PCE = 1.71%, JSC = 8.15 mA/cm2, VOC = 0.4 V, FF = 49%) and the obtained data are well comparable with reference, Sipro‐OMeTAD (PCE = 4.76%, JSC = 12.27 mA/cm2, VOC = 0.84 V, FF = 45%). Conclusively, the study furnishes a deeper understanding of the intricacies involved in the structural modification of in low‐cost HTM in achieving an enhanced performance of the devices.