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) of perovskite surface, and subsequent PEAI further induces additional negative dipole and causes the surface E 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.