Non-covalent functionalized Schottky interface at Ti3C2Tx/c-Si van der Waals heterojunction

Synergistic interaction between 2D materials and organic molecules presents an additional dimension for tuning their intrinsic properties. Herein, we aim to tune the work function of 2D Ti3C2Tx by introducing ultrathin interlayers of organic dipoles (O.D.) with a defined dipole moment value. Interface engineering is achieved through the inclusion of poly(ethylene)amine (PEI 0.1 %) and third generation poly(amido-)amine (PAMAM G3), between the Ti3C2TX and c-Si. c-Si/O.D./Ti3C2Tx heterostructures were fabricated by simple drop casting of the aqueous MXene solution on O.D. coated c-Si substrates. Charge transport properties of the fabricated Schottky diodes with structure of c-Si/O.D./Ti3C2TX were evaluated through systematic analysis of the I-V and C-V characteristics. Our investigations reveal that diodes featuring O.D. as interlayers exhibit substantially reduced reverse saturation current density (J0) and enhanced built-in potential (Vbi). Work function of the fabricated c-Si/MXene/O.D. structures were evaluated from the ultraviolet photo-emission spectroscopy (UPS) measurements. We report a significant reduction in the work function value of Ti3C2Tx from 5.8 eV to 4.2 eV for Ti3C2Tx/PEI 0.1 % and 3.3 eV for Ti3C2Tx/PAMAM-G3 heterostructures. Our study introduces an innovative approach for modifying the work function of Ti3C2Tx through the incorporation of O.D., highlighting the versatility of MXene electrodes to shape the future optoelectronic devices.