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 (CZ<inf>1-2</inf>), 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 ?<inf>abs</inf> and ?<inf>emi</inf> 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 CZ<inf>1-2</inf> as HTMs to evaluate their photovoltaic performances. Their results indicated that the device with CZ<inf>1</inf> displayed enhanced PCE of 2.55% (J<inf>SC</inf>= 7.85 mA/cm2, V<inf>OC</inf>= 0.79 V and FF = 40%) than the cell with CZ<inf>2</inf> (PCE = 1.71%, J<inf>SC</inf>= 8.15 mA/cm2, V<inf>OC</inf> = 0.4 V, FF = 49%) and the obtained data are well comparable with reference, Sipro-OMeTAD (PCE = 4.76%, J<inf>SC</inf>= 12.27 mA/cm2, V<inf>OC</inf> = 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. © 2021 The Authors. Electrochemical Science Advances published by Wiley-VCH GmbH.