Ti₃C₂T_<i>x</i>/Self-Assembled Monolayer Composite Interface for Enhanced Hole Transport in Inverted Perovskite Solar Cells

Two-dimensional transition metal carbide Ti3C2Tx, with its large surface area, excellent conductivity, and abundant surface terminations (Tx), has found broad applications in optoelectronic devices. To address issues such as energy level misalignment, low conductivity, and surface defects at the HTL/perovskite interface in inverted perovskite solar cells (p-i-n PSCs), this study proposes an interface passivation strategy based on MXene to regulate the buried interface of NiOx/MeO-2PACz-based p-i-n PSCs. Experimental results show that Ti3C2Tx, when used as an interface passivation layer, increases the work function (WF) of MeO-2PACz, facilitating energy level alignment. The abundant hydroxyl groups (−OH) on the surface of Ti3C2Tx undergo continuous hybridization reactions with P atoms, forming strong Ti–O–P covalent bonds that provide an effective pathway for hole transport, thereby reducing charge accumulation at the interface. Additionally, MXene-doped MeO-2PACz was used as a control group to further reveal the dual passivation mechanism of MXene on both the MeO-2PACz and the underlying perovskite interface. Ultimately, compared to PSCs with undoped HTLs, the power conversion efficiency (PCE) of PSCs increased by 6% with HTL doping and by 10.7% with interface passivation. This study expands the application of Ti3C2Tx in HTLs and provides a pathway for its use in the fabrication of highly efficient and stable PSCs.