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Improving the Conductivity of Amide-Based Small Molecules through Enhanced Molecular Packing and Their Application as Hole Transport Mediators in Perovskite Solar Cells

Lookup NU author(s): Eman Alkhudhayr, Dumitru Sirbu, Miriam Fsadni, Bening Muhammad, Dr Paul Waddell, Professor Mike ProbertORCiD, Professor Thomas Penfold, Dr Toby HallamORCiD, Professor Elizabeth GibsonORCiD, Dr Pablo Docampo



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Organic–inorganic hybrid halide perovskite solar cells (PSCs) have attracted substantial attention from the photovoltaic research community, with the power conversion efficiency (PCE) already exceeding 26%. Current state-of-the-art devices rely on Spiro-OMeTAD as the hole-transporting material (HTM); however, Spiro-OMeTAD is costly due to its complicated synthesis and expensive product purification, while its low conductivity ultimately limits the achievable device efficiency. In this work, we build upon our recently introduced family of low-cost amide-based small molecules and introduce a molecule (termed TPABT) that results in high conductivity values (∼10–5 S cm–1upon addition of standard ionic additives), outperforming our previous amide-based material (EDOT-Amide-TPA, ∼10–6 S cm–1) while only costing an estimated $5/g. We ascribe the increased optoelectronic properties to favorable molecular packing, as shown by single-crystal X-ray diffraction, which results in close spacing between the triphenylamine blocks. This, in turn, results in a short hole-hopping distance between molecules and therefore good mobility and conductivity. In addition, TPABT exhibits a higher bandgap and is as a result more transparent in the visible range of the solar spectrum, leading to lower parasitic absorption losses than Spiro-OMeTAD, and has increased moisture stability. We applied the molecule in perovskite solar cells and obtained good efficiency values in the ∼15% range. Our approach shows that engineering better molecular packing may be the key to developing high-efficiency, low-cost HTMs for perovskite solar cells.

Publication metadata

Author(s): Alkhudhayr EAA, Sirbu D, Fsadni M, Vella B, Muhammad BT, Waddell PG, Probert MR, Penfold TJ, Hallam T, Gibson EA, Docampo P

Publication type: Article

Publication status: Published

Journal: ACS Applied Energy Materials

Year: 2023

Volume: 6

Issue: 22

Pages: 11573-11582

Print publication date: 27/11/2023

Online publication date: 08/11/2023

Acceptance date: 23/10/2023

Date deposited: 09/11/2023

ISSN (electronic): 2574-0962

Publisher: American Chemical Society


DOI: 10.1021/acsaem.3c01988


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