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 π-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 µW·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.