LAUSR

Abstract Nucleation and growth process of electrodeposited polymer determine its morphology, thus its function and applicability. In this work, we show how minute changes in polymerization condition, like current density and electrolyte concentration, alter nucleation pattern of polythiophene. Different nucleation patterns in turn give rise to different morphology and functional properties. Polythiophene was electrochemically synthesized on indium tin oxide (ITO) using boron trifluoride diethyl etherate (BF3.Et2O) electrolyte. At constant current density (8 μA/cm2), 20 vol% electrolyte gives rise to dendritic structures, while pure electrolyte gives rise to uniform film. Similarly, if current density was increased (0.08–0.4 mA/cm2) in 20 vol% electrolyte, dendritic structures were completely suppressed and again uniform polymer film was obtained. Although electrical properties are compromised in the dendritic sample owing to the higher surface roughness, dendritic structures efficiently guide light and are shown to be a good candidate for photonic and energy applications. On the other hand; uniform polythiophene, obtained at high current density and electrolyte concentration shows enhanced redox capacity and electrical conductivity. Utilizing optical and electrical properties of smooth polythiophene films (without dendrites), basic photovoltaic (PV) device (Glass/ITO/PT/P3HT:PC61BM/Al) was constructed using electrochemically grown polythiophene as Hole-Transporting Layer (HTL). Fabricated device exhibits significant photovoltaic performance with comparable efficiencies of 0.98–1.24%. Such electrochemically grown polythiophene thin films can be a substitute for other HTLs (like PEDOT: PSS) in photovoltaic devices.