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How to design more efficient hole-transporting materials for perovskite solar cells? Rational tailoring of the triphenylamine-based electron donor

Abstract

Designed with a symmetrical core naphthatetrathiophene (NTT) and triphenylamine (TPA)-based side arms, a series of novel organic small molecule hole-transporting materials are simulated for perovskite solar cells (PSCs) by using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. As a fundamental understanding, the energy level alignments and the charge transport behavior are explored for their potential applications. Our results show that, adding oxygen-bridge between the neighboring phenyl groups of TPA side arms makes the highest occupied molecular orbital (HOMO) levels up-shifted, whereas the carbon-carbon single bond stabilizes the HOMOs about 0.3~0.4 eV. By structural tailoring of the TPA side arms, the HOMO levels of new designed molecules range from -5.08 eV to -5.61 eV, which provides more new possibilities for the interfacial energetic regulations. Meanwhile, our results also indicate that the quasi-planar molecular architecture and the delocalized frontier molecular orbitals can effectively enhance the electronic coupling between adjacent molecules. In addition, the reorganization energies are distinctly lowered in the cases of mixed carbon-carbon bond and oxygen-bridge, and the double oxygen-bridge models. As a result, these molecules with additional carbon-carbon bond and oxygen-bridge exhibit high hole mobilities. Several promising candidates are proposed toward more efficient PSCs, and more importantly, this work offers some new insights for the design of organic small molecule materials.

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Publication details

The article was received on 11 Jun 2018, accepted on 07 Oct 2018 and first published on 08 Oct 2018


Article type: Paper
DOI: 10.1039/C8NR04730H
Citation: Nanoscale, 2018, Accepted Manuscript
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    How to design more efficient hole-transporting materials for perovskite solar cells? Rational tailoring of the triphenylamine-based electron donor

    Y. Xu, W. Ding and Z. Sun, Nanoscale, 2018, Accepted Manuscript , DOI: 10.1039/C8NR04730H

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