Optical and electrical anisotropy in Langmuir–Schaefer polythiophene films: evidence of orientation‐controlled photoelectrical response

Abstract Polythiophenes are extensively studied semiconducting polymers due to their relevance in optoelectronic applications. While previous research has addressed their structural and optical anisotropy, limited attention has been paid to thin films fabricated via the Langmuir–Schaefer (LS) technique, particularly regarding the influence of deposition orientation. In this study, we examine the anisotropic behavior of poly(3‐hexylthiophene) (P3HT) and poly(3‐octylthiophene) (P3OT) thin films deposited by the LS technique at varying angles. Structural, optical and electrical analyses confirm that both polymers form highly ordered films, with P3OT exhibiting greater optical and electrical anisotropy than P3HT. The highest photocurrent was observed in P3OT films deposited with interdigitated electrodes oriented orthogonally to the LS trough's movable barriers, demonstrating an interesting correlation between deposition orientation and charge transport efficiency. Furthermore, wavelength‐dependent photoconductivity measurements reveal distinct photoexcitation mechanisms in P3OT LS films. These results underscore the potential of orientation‐controlled LS deposition as a strategy to enhance charge generation and transport in polythiophene‐based films, offering new avenues for the design of high‐performance organic optoelectronic devices. © 2026 Society of Chemical Industry.