Ti₃C₂T_<i>x</i>/Self-Assembled Monolayer CompositeInterface for EnhancedHole Transport in Inverted Perovskite Solar Cells

Two-dimensional transition metal carbide Ti₃C₂T_<i>x</i>, with its large surface area, excellent conductivity, and abundant surface terminations (T_<i>x</i>), 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 NiO_<i>x</i>/MeO-2PACz-based p-i-n PSCs. Experimental results show that Ti₃C₂T_<i>x</i>, 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 Ti₃C₂T_<i>x</i> 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 Ti₃C₂T_<i>x</i> in HTLs and provides a pathway for its use in the fabrication of highly efficient and stable PSCs.