p–p Orbital Coupling Enhanced Exciton Dissociation for High‐Performance and Stable FAPbI ₃ Quantum Dot Solar Cells

The photovoltaic gap between perovskite quantum dots and polycrystalline films mainly arises from the high exciton binding energy (E b ∼100 meV) in quantum dots. In this work, we introduce a p–p orbital coupling strategy using triphenylmethyl mercaptan (TPSh) to lower E b , thereby enhancing exciton dissociation and charge transfer rates in perovskite quantum dot solar cells. The results indicate that strong coordination of Pb‐S bonds induce p–p orbital coupling between Pb 6 p and S 3 p orbitals, which significantly reduces E b from 128.4 to 68.4 meV, and increases the carrier density from 2.23 × 10 14 cm −3 to 2.73 × 10 14 cm −3 as confirmed by Hall effect measurements. Meanwhile, the steric hindrance provided by TPSh further inhibits surface ion migration on the quantum dot surface, greatly improving environmental stability. Consequently, TPSh‐treated FAPbI 3 quantum dot solar cells achieve a champion efficiency of 17.66% (compared to 15.71% for the control) and retaining 90% of their initial efficiency after 1000 h of unencapsulated operation following ISOS‐L‐1I protocols. This work uncovers an orbital coupling‐based mechanism to regulate exciton dynamics, providing a novel approach to advance quantum dot optoelectronic devices.