Bimolecular Passivation-Dipole Bridge for Highly Efficient Inverted Perovskite Solar Cells with Low Nonradiative Recombination Loss

Constructing charge-selective heterointerface with minimized defect state and matched energy level alignment is essential to reduce nonradiative recombination for achieving high-performance perovskite solar cells (PSCs). Herein, a bimolecular passivation-dipole bridge comprised of sodium phenylmethanesulfonate (SPM) and 2-phenylethylammonium iodide (PEAI) is carefully developed to regulate perovskite heterointerface. SPM passivates defect states and upshifts Fermi level (E_F) of perovskite surface, and subsequent PEAI further induces additional negative dipole and causes the surface E_F of perovskite pinning to negative polaron transport state of electron transport layer PCBM, which significantly promotes electron extraction at the perovskite electron-selective contact. These advantages are confirmed by a remarkably improved efficiency from 21.74% for control to 25.12% for treated PSC with excellent stability. Moreover, corresponding nonradiative recombination loss impressively diminishes from 123 to 70 meV, and charge transport-induced fill factor loss is only 3.00%. This work provides a promising approach via passivation-energetic synergy for engineering perovskite heterointerface toward highly efficient and stable PSCs.