High-Efficiency Perovskite Solar Cells with Improved Interfacial Charge Extraction by Bridging Molecules.

The interface between the perovskite layer and electron transporting layer is a critical determinate for the performance and stability of perovskite solar cells (PSCs). The heterogeneity of the interface critically affects the carrier dynamics at the buried interface. To address this, a bridging molecule, (2-aminoethyl)phosphonic acid (AEP), is introduced for the modification of SnO2/perovskite buried interface in n-i-p structure PSCs. The phosphonic acid group strongly bonds to the SnO2 surface, effectively suppressing the surface carrier traps and leakage current, and uniforming the surface potential. Meanwhile, the amino group influences the growth of perovskite film, resulting in higher crystallinity, phase purity, and fewer defects. Furthermore, the bridging molecules facilitate the charge extraction at the interface, as indicated by the femtosecond transient reflection (fs-TR) spectroscopy, leading to champion power conversion efficiency (PCE) of 26.40% (certified 25.98%) for PSCs. Additionally, the strengthened interface enables improved operational durability of ≈1400 h for the unencapsulated PSCs under ISOS-L-1I protocol.

Realizing Stable Perovskite Solar Cells with Efficiency Exceeding 25.6% Through Crystallization Kinetics and Spatial Orientation Regulation.

Organic-inorganic hybrid perovskites have emerged as highly promising candidates for photovoltaic applications, owing to the exceptional optoelectronic properties and low cost. Nonetheless, the performance and stability of solar cells suffer from the defect states of perovskite films aroused by non-optically active phases and non-centralized crystal orientation. Herein, a versatile organic molecule, Hydantoin, to modulate the crystallization of perovskite, is developed. Benefiting from the diverse functional groups, more spatially oriented perovskite films with high crystallinity are formed. This enhancement is accompanied by a conspicuous reduction in defect density, yielding efficiency of 25.66% (certified 25.15%), with superb environmental stability. Notably, under the standard measurement conditions (ISOS-L-1I), the maximum power point (MPP) output maintains 96.8% of the initial efficiency for 1600 h and exhibits excellent ion migration suppression. The synergistic regulation of crystallization and spatial orientation offers novel avenues for propelling perovskite solar cell (PSC) development.

Highly Efficient and Stable Perovskite Solar Cells: Competitive Crystallization Strategy and Synergistic Passivation.

Defects of perovskite (PVK) films are one of the main obstacles to achieving high-performance perovskite solar cells (PSCs). Here, the authors fabricated highly efficient and stable PSCs by introducing prolinamide (ProA) into the PbI2 precursor solution, which improves the performance of PSCs by the competitive crystallization and efficient defect passivation of perovskite. The theoretical and experimental results indicate that ProA forms an adduct with PbI2 , competes with free I- to coordinate with Pb2+ , leads to the increase of the energy barrier of crystallization, and slows down the crystallization rate. Furthermore, the dual-site synergistic passivation of ProA is revealed by density functional theory (DFT) calculations and experimental results. ProA effectively reduces non-radiative recombination in the resultant films to improve the photovoltaic performance of PSCs. Notably, ProA-assisted PSCs achieve 24.61% power conversion efficiency (PCE) for the champion device and the stability of PSCs devices under ambient and thermal environments is improved.