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Nonfullerene acceptors with an N-annulated perylene core and two perylene diimide units for efficient organic solar cells
摘要： We have designed and synthesized a series of perylene based A-D-A type chromophores, which are composed of two electron deficient perylene diimides (PDI) and one electron rich N-annulated perylene (NP). By virtue of the bi-axial rigid skeleton of the flat NP unit, the intermolecular aggregation is efficiently suppressed, leading to a very small red-shift of absorption being observed in going from solutions to films. In addition, the molar extinction coefficients have been significantly elevated in case of sulfur or selenium annulation at the bay positions of the PDI units. Quantum calculation is employed for the geometry optimization to further understand the contributions of different excitations to the UV-vis absorption spectra. Morphology studies demonstrate that the twisted conformations of these acceptors are favorable for the formation of suitable phase separation in the as-cast films. The heteroatom annulation could force the PDI plane to take on a more planar conformation, which is favorable to have closer π?π stacking for efficient electron transportation. Finally, the as-cast devices based on PBDB-T:NP-diPDI-Se display a power conversion efficiency (PCE) of 6.25% with a Voc of 0.98 V, a Jsc of 11.73 mA/cm2 and an FF of 54.13%.
关键词： N-annulated perylene,Nonfullerene acceptors,Organic solar cells,Power conversion efficiency,Perylene diimide
更新于2025-09-19 17:13:59
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Fusing Thienyl with N-Annulated Perylene Dyes and Photovoltaic Parameters for Dye-Sensitized Solar Cells
摘要： Due to the role of dye in dye-sensitized solar cells (DSSCs), design novel dye sensitizer is effective strategy to improve power conversion efficiency. To this end, the fundamental issue is the understanding sensitizer’s trilateral relationship among molecular structure, optoelectronic properties and photovoltaic performance. Here, on the one hand, to investigate the relationship between molecular structure and properties, considering the good performance of N-annulated perlyene dye sensitizers, the geometries, electronic structures and excitations of the selected representative organic dye sensitizers C276, C277, C278 and the dyes adsorbed on TiO2 clusters were calculated. It is found that, fusing thienyl to N-annulated perlyene can elevate the highest occupied molecular orbital (HOMO) energies, reduce orbital energy gap, increase density of states, expand HOMO to benzothiadiazole moiety, enhance charge transfer excitation, elongate fluorescence lifetime, amplify light harvesting efficiency and induce red-shift of absorption spectra. The transition configurations and molecular orbitals of dye adsorbed systems support that the electron injection in DSSCs based on these dyes are fast mode. On the other hand, to exposure the relationship between properties and performance, based upon extensive analysis of electronic structures and excitation properties of these dye sensitizers and the dye adsorbed systems, we present new quantities as open-circuit voltage and short-circuit current density descriptors, which celebrate the quantitative bridge between the photovoltaic parameters and the electronic structure related properties. The results of this work are critical for design novel dye sensitizers for solar cells.
关键词： electronic structures,N-annulated perylene dyes,photovoltaic parameters,dye-sensitized solar cells,excitation properties
更新于2025-09-19 17:13:59
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Hole transport material based on modified N-annulated perylene for efficient and stable perovskite solar cells
摘要： N-annulated perylene based materials show outstanding and tunable optical and physical properties, making them suitable to be charge transport materials for optoelectronic applications. However, this type of materials has so far not been well studied in solar cells. Here, we develop a new hole transport material (HTM), namely S5, based on perylene building block terms, for organic-inorganic hybrid perovskite solar cells (PSCs). We have systematically studied the influences of the film thickness of S5 on their photovoltaic performance, and a low concentration of S5 with a thinner HTM film is favorable for obtaining higher solar cell efficiency. S5 shows excellent energy alignment with perovskite as well as high-quality thin film formation, and the PSCs based on S5 as HTMs show remarkable power conversion efficiency (PCE) of 14.90% with a much higher short-circuit photocurrent than that for conventional HTM spiro-OMeTAD (PCE = 13.01%). We conclude that the superior photocurrent for S5 is mainly attributed to the enhanced interfacial hole transfer kinetics as well as the high hole conductivity. In addition, we have investigated the stability of N-annulated perylene derivative as HTMs in PSCs devices, showing that the unencapsulated devices based on S5 demonstrate outstanding stability by remaining 85% of initial PCEs in ambient condition with a relative humidity of ~30–45% for 500 h, while for devices with spiro-OMeTAD the cell efficiency degrade to 57% of initial performance at the same conditions.
关键词： High stability,N-annulated perylene,Hole-transporting materials,Perovskite solar cells
更新于2025-09-16 10:30:52