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Effects of thiophene substituents on hole-transporting properties of dipolar chromophores for perovskite solar cells
- Cui, Jianyu, Rao, Wei, Hu, Weixia, Zhang, Zemin, Shen, Wei, Li, Ming, He, Rongxing
- Journal of materials science 2018 v.53 no.9 pp. 6626-6636
- absorption, electrochemistry, photovoltaic cells, spectral analysis, thiophene, wavelengths
- We present a theoretical investigation of thiophene substituent effects on the electrochemical properties of dipolar chromophores (TCNE, TCNE22 and TCNE24) as hole-transporting materials (HTMs) in perovskite solar cells (PSCs). Herein, the material properties in crystalline phases are explored by using the first-principle calculations combined with Marcus theory. The results show that the increased number of thiophene substituents for TCNE, TCNE22 and TCNE24 results in a redshift of the absorption spectrum (27–46 nm). Furthermore, both TCNE22 and TCNE24 have maximum absorption peaks at a wavelength of 400 nm. Most importantly, the molecular planarity is improved effectively, which generates strong intermolecular face-to-face π–π packing interaction. The higher hole mobility of TCNE24 (2.069 × 10⁻¹ cm² V⁻¹ s⁻¹) with four thiophene substituents is obtained due to the face-to-face π–π packing. The new designed TCNE24 not only has excellent spectral property, but also has strong hole mobility. Therefore, TCNE24 is a promising organic small-molecule HTMs. Our work provides theoretical guidance for designing higher-performance HTMs in PSCs.