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.
To explore the charge transport through metalla-aromatics building blocks, three metallacycles complexes were synthesized, and their single-molecule conductances were characterized by using mechanically controllable break junction technique. It is found that the conductance of the metallacycles junction with phosphonium group is more than 1 order of magnitude higher than that without phosphonium group. X-ray diffraction and UV-vis absorption spectroscopy suggested that the attached phosphonium group makes metallacycles more delocalized, which shortened the preferred charge transport pathway and significantly enhanced the single-molecule conductance. This work revealed that the delocalization of metalla-aromatics could be used to switch the charge transport pathway of single-molecule junctions and thus tune the charge transport abilities significantly.
Tin‐based perovskite solar cells (TPSCs) are attracting intense research interest due to their excellent optoelectric properties and eco‐friendly features. To further improve the device performance, developing new fullerene derivatives as electron transporter layers (ETLs) is highly demanded. Four well‐defined regioisomers (trans‐2, trans‐3, trans‐4, and e) of diethylmalonate‐C60 bisadduct (DCBA) are isolated and well characterized. The well‐defined molecular structure enables us to investigate the real structure‐dependent effects on photovoltaic performance. It is found that the chemical structures of the regioisomers not only affect their energy levels, but also lead to significant differences in their molecular packings and interfacial contacts. As a result, the devices with trans‐2, trans‐3, trans‐4, and e as ETLs yield efficiencies of 11.69%, 14.58%, 12.59%, and 10.55%, respectively, which are higher than that of the as‐prepared DCBA‐based (10.28%) device. Notably, the trans‐3‐based device also demonstrates a certified efficiency of 14.30%, representing one of the best‐performing TPSCs.
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