Perovskite solar cells fabricated without pre‐deposited hole‐transport layers (HTL‐free PSCs) offer compelling advantages in simplicity and cost. However, their performance and stability are severely limited by non‐radiative recombination at the perovskite/electron‐transport layer (ETL) interface. While mono‐component phenethylammonium (PEA) passivators can passivate surface defects, their limited passivation capacity, inefficient charge transfer, and instability under photothermal stress hinder further advancement. Herein, a bimolecular co‐modification (BCM) strategy by combining a new molecular passivator, tran‐4‐hydroxy‐D‐proline hydrochloride (THDPH), and PEABr to comprehensively manage the perovskite/ETL interface is proposed. Theoretical and experimental analyses reveal that THDPH concurrently interacts with FA + and Pb 2+ through hydrogen bonds and coordination, respectively. This concerted action induces favorable grain reorientation and suppresses non‐radiative recombination on the perovskite surface. Based on this, the BCM strategy effectively improves crystallization quality, passivates surface and bulk defects, and optimizes interfacial energy alignment. Consequently, the HTL‐free BCM PSC achieves a champion power conversion efficiency of 26.55%. BCM devices also demonstrate significantly enhanced operational stability, retaining 90% of their initial efficiency after 1000 h of continuous illumination. The BCM strategy further exhibits good universality across different bandgaps of PSCs (1.68 and 1.85 eV). This work provides an effective and universal interface design strategy for developing high‐performance perovskite photovoltaics.
Crystallographic orientation governs lattice strain, defect formation, and stability in perovskite solar cells, yet precise control remains challenging in sequential deposition due to the intrinsic growth dominance of low‐surface‐energy (100) facets. Here, we report an interference crystallization strategy that reshapes facet competition by modulating A‐site intercalation kinetics. Incorporation of a sulfonate‐based additive into the PbI 2 precursor imposes facet‐dependent kinetic perturbation during FA + insertion. Preferential adsorption of this additive on the (100) surface restricts A‐site accessibility and selectively retards its growth, whereas weaker interaction with the (111) surface preserves intercalation kinetics and enables its competitive development. This asymmetric interference establishes a balanced (100)/(111) orientation distribution, alleviating residual lattice strain associated with single‐facet dominance. The coexistence of both facets integrates their complementary merits, combining the superior optoelectronic quality of (100) with the enhanced moisture tolerance of (111). Meanwhile, strong surface adsorption of this additive on both facets provides additional defect passivation, suppressing non‐radiative recombination. Devices fabricated via this strategy achieve a power conversion efficiency of 26.41% and exhibit negligible degradation after 1300 h maximum power point tracking, demonstrating interference‐mediated crystallization as a viable pathway for orientation regulation in sequentially deposited perovskites.
Dielectric constant (ε r ) of non‐fullerene acceptors (NFAs) is a crucial parameter in organic solar cells (OSCs), significantly influencing exciton dissociation efficiency and charge recombination dynamics. However, the state‐of‐the‐art NFAs typically exhibit relatively low dielectric constants (ε r ≈ 3–5), which inherently limit device performance by promoting substantial recombination losses. Herein, a new guest acceptor named L8‐BO‐FO is reported by replacing the branched alkyl chains on L8‐BO with dimethyl ether units, which presents a higher ε r value of 7.41 than that of L8‐BO (4.57). Subsequently, the high‐ε r L8‐BO‐FO was introduced into the PM6:L8‐BO system to improve the dielectric property of the active layer, which, encouragingly, increases the ε r value of the active layer, accelerates exciton dynamics, and suppresses the nonradiative charge recombination. As a result, the power conversion efficiency (PCE) of the ternary OSCs is boosted up to 21.0%. Surprisingly, the ternary OSCs maintained an outstanding PCE of 19.1% even when the active‐layer thickness increased to 300 nm. This work brings new insights into the design of high‐performance OSCs with excellent thickness tolerance by dielectric engineering, which is essential for high‐throughput and scale‐up fabrication of OSCs.