Bidentate mode coordinated Ti3CNTx MXene-controlled interfacial engineering enables high-performance indoor organic photovoltaic devices

Two-dimensional MXenes demonstrate exceptional optoelectronic properties and tunable surface terminations, making them highly desirable materials for advanced organic photovoltaic (OPV) devices in indoor settings. This study introduced a solution-processed hybrid hole-transport layer (HTL) composed of a blend of 2-(9H-carbazol-9-yl)ethyl]phosphonic acid and titanium carbonitride (2PACz-Ti3CNTx). Introducing Ti3CNTx into 2PACz enhanced the work function for improved hole transport and also induced molecular alignment and interface dipole changes via formation of Ti-O-P covalent bond. This synergistic interaction led to atomic charge polarization, improving the hole-transport kinetics at the heterointerface of 2PACz and Ti3CNTx. Furthermore, the large surface area of conductive MXene and its chemical interaction with pi-conjugated 2PACz promote the conductivity and charge-transfer pathways, improving the device's performance. Consequently, OPV devices employing 2PACz-Ti3CNTx HTLs achieved the maximum power conversion efficiency of 30.3 % under a light-emitting diode lamp (1000 lx) and an output power density of 413 mu W.cm(-2) under a halogen lamp (1000 lx), corresponding to enhancements of approximately 16 % and 12 %, respectively, compared to OPV devices based on undoped HTLs. These results highlight new opportunities for further exploration of MXene compositions in high-performance indoor OPV devices.