MeO-2PACz Self-Assembled Monolayer as a Dopant-Free Electron-Selective Contact for Significantly Enhanced Silicon Solar Cells

Dopant-free carrier-selective contacts are essential for low-cost, high-efficiency crystalline silicon (c-Si) photovoltaics. Here, we demonstrate an efficient electron-selective contact by inserting a MeO-2PACz self-assembled monolayer (SAM) at the n-Si/Al interface. This molecular interlayer enables linear ohmic contact with a low contact resistivity of 7.79 mΩ·cm2. Crucially, MeO-2PACz reduces the Al work function (WF) from 4.25 to 3.50 eV, simultaneously suppressing Fermi level pinning and lowering the Schottky barrier for enhanced electron tunneling. The optimized SAM-modified solar cells achieve a power conversion efficiency of 18.93%─a 20.81% enhancement over control devices─with a high fill factor of 82.61%. This strategy simplifies device architecture and mitigates intrinsic losses of doped contacts, providing a scalable pathway toward industrial silicon photovoltaics.