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D-??-D molecular semiconductors for perovskite solar cells: the superior role of helical versus planar ??-linker
摘要： Controlling the mode of molecular packing and the size of molecular aggregate are of fundamental importance for high-performance charge transporting materials in next-generation optoelectronic devices. To clarify the peculiar role of helicene as kernal blocks in the exploration of unconventional organic semiconductors, in this work thia[5]helicene (T5H) is duplicately aminated with electron-donating dimethoxydiphenylamine to afford T5H-OMeDPA, which is systematically compared with its perylothiophene (PET) congener (PET-OMeDPA). On the basis of quantum theory of atoms in molecules and energy decomposition analysis of single-crystals, it is suprisingly found that while π-π stacking of planar PET is stronger than that of helical T5H, this desirable effect for charge transport of organic semiconductors is completely lost for donor-π-donor (D-π-D) typed PET-OMeDPA, but is retained for T5H-OMeDPA to a large extent. Consequently, T5H-OMeDPA single-crystal presents an about 5 times higher theoretical hole-mobility than PET-OMeDPA. More critically, the solution-processed racemic glassy film of T5H-OMeDPA displays a 3 times higher hole-mobility in comparison with the PET-OMeDPA counterpart, due to a larger domain of molecular aggregate. With respect to PET-OMeDPA, there is a weaker electronic coupling of helical T5H-OMeDPA with perovskite, leading to a reduced interfacial charge recombination. Due to reduced transport resistance and enhanced recombination resistance, perovskite solar cells with T5H-OMeDPA exhibit a power conversion efficiency of 21.1%, higher than that of 19.8% with PET-OMeDPA and that of 20.6% with spiro-OMeTAD control.
关键词： charge transport,perovskite solar cells,helicene,molecular semiconductors,π-π stacking
更新于2025-09-23 15:21:01
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Evaluating intrinsic mobility from transient terahertz conductivity spectra of microcrystal samples of organic molecular semiconductors
摘要： In microcrystal samples of the prototypical organic molecular semiconductors rubrene and C10-DNTT (2,9-didecyl-dinaphtho[2,3-b:20,30-f]thieno[3,2-b]thiophene), we measured spectra of complex optical conductivity caused by photocarriers with optical-pump terahertz-probe spectroscopy. We analyzed the ~r xe T spectra using the Drude-Smith model and evaluated the DC mobility lDC, which includes extrinsic effects, and the intrinsic mobility lint. The resulting lDC and lint values are comparable to the mobility values obtained using transport measurements of polycrystalline and single-crystalline ?eld-effect transistors, respectively. This correspondence demonstrates that the intrinsic mobility values of organic molecular semiconductors can be evaluated from the measurements of microcrystal samples using transient terahertz spectroscopy.
关键词： mobility,C10-DNTT,organic molecular semiconductors,terahertz spectroscopy,rubrene
更新于2025-09-23 15:19:57