Designing functional fullerenes with roles beyond defect passivation and electron‐transporting for perovskite solar cells (PSCs) is essential to the development of fullerenes and PSCs. Here, the authors design and synthesize a functional fullerene, FPD, composed of a C60 cage, a porphyrin ring, and three pentafluorophenyl groups. The structure features of FPD enable it can form chemical interactions with the perovskite lattices. These interactions enhance the defect passivation effect and prevent the decomposition of perovskite under irradiation. As a result, the FPD‐based device yields an improved power conversion efficiency of 23% with substantially enhanced operational stability (T80 > 1500 h). Furthermore, once got damaged, the FPD can prevent lead leakage by forming a stable and water‐insoluble complex (FPD‐Pb). Their findings provide a novel strategy to achieve high‐performance and eco‐friendly PSCs with functional fullerene materials.

Understanding the function of moisture on perovskite is challenging since the random environmental moisture strongly disturbs the perovskite structure. Here, we develop various N2-protected characterization techniques to comprehensively study the effect of moisture on the efficient cesium, methylammonium, and formamidinium triple-cation perovskite (Cs0.05FA0.75MA0.20)Pb(I0.96Br0.04)3. In contrast to the secondary measurements, the established air-exposure-free techniques allow us directly monitor the influence of moisture during perovskite crystallization. We find a controllable moisture treatment for the intermediate perovskite can promote the mass transportation of organic salts, and help them enter the buried bottom of the films. This process accelerates the quasi-solid-solid reaction between organic salts and PbI2, enables a spatially homogeneous intermediate phase, and translates to high-quality perovskites with much-suppressed defects. Consequently, we obtain a champion device efficiency of approaching 24% with negligible hysteresis. The devices exhibit an average T80-lifetime of 852 h (maximum 1210 h) working at the maximum power point.

Perovskite light-emitting diodes (Pero-LEDs) with external quantum efficiencies (EQEs) of over 20% have been achieved in the last several years. However, the reproducibility of such high-efficiency Pero-LEDs is still low. The perovskite film quality, especially for the non-radiative defects, is crucial in determining the device performance. These defects may lie in bulk grains, grain boundaries, and interfaces of the as-formed perovskite films. Here, a polymer infiltrative treatment method is developed to realize effective and universal defect passivation. Specifically, poly(vinylidene fluoride) (PVDF) polymer chains are blended into the perovskite films before they are fully crystallizing. This infiltrative treatment method can regulate crystallization and passivate defects through the chemical interactions of perovskite lattices and PVDF. As a result, high-quality perovskite films with void-free surfaces and few-defect crystals are obtianed. The corresponding Pero-LEDs show a maximum EQE of 22.29% and an average EQE of 20.44 ± 0.73% based on a statistical analysis of 50 devices, exhibiting excellent reproducibility. The work provides better insights into controlling crystal growth and defect passivation via polymer-assisted methods for efficient Pero-LEDs.

Fullerene derivatives are considered excellent materials for the extraction and transportation of electrons in the production of efficient tin-based perovskite solar cells (TPSCs). However, it is not clear how the molecular structure of fullerene derivatives affects the efficiency and stability of TPSCs. In this study, the effects of fullerene derivatives, (6,6)-phenyl-C61-butyric acid hexyl ester (PCBH) and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM), with different functional groups, on photovoltaic performance were investigated. The flexible alkyl chain of PCBH effectively improved the film morphology and stability, the electron extraction and transport capabilities, and the interface contact of fullerene and perovskite. As a result, the PCBH-based TPSC yielded a higher efficiency, of 9.21%, than the PCBM-based devices (7.54%). More importantly, the PCBH-based films exhibited higher stability and effectively suppressed the oxidation of Sn2+ by inhibiting oxygen permeation. Therefore, the PCBH-based devices exhibited significantly enhanced stability. This result indicates that optimizing the functional group of fullerene derivatives is crucial for improving the efficiency and stability of TPSCs.

No abstract