Effect of alkyl chain length on the properties of triphenylamine-based hole transport materials and their performance in perovskite solar cellsElectronic supplementary information (ESI) available: Experimental details of the synthesis of the DATPA derivatives, additional electrochemical measurments, DSC curves, X-ray structures, extended crystallographic table, powder diffraction data, calculated HOMO and LUMO energy levels of all DATPA derivatives, transfer characteristic curves for the mobilit

A new series of diacetylide-triphenylamine (DATPA) derivatives with five different alkyl chains in the para position, MeO, EtO, n PrO, i PrO and BuO, were synthesised, fully characterised and their function as hole-transport materials in perovskite solar cells (PSC) studied. Their thermal, optical and electrochemical properties were investigated along with their molecular packing and charge transport properties to analyse the influence of different alkyl chains in the solar cell parameters. The shorter alkyl chain facilitates more compact packing structures which enhanced the hole mobilities and reduced recombination. This work suggests that the molecule with the methoxy substituent (MeO) exhibits the best semiconductive properties with a power conversion efficiency of up to 5.63%, an open circuit voltage ( V oc ) of 0.83 V, a photocurrent density ( J sc ) of 10.84 mA cm −2 and a fill factor of 62.3% in perovskite solar cells. Upon replacing the methoxy group with longer alkyl chain substituents without changing the energy levels, there is a decrease in the charge mobility as well as PCE ( e.g. 3.29% for BuO-DATPA). The alkyl chain length of semiconductive molecules plays an important role in achieving high performance perovskite solar cells. Five triarylamine derivatives with different para -alkoxy chains were compared as hole-transport materials in perovskite solar cells.