An electric bias can shift the Fermi level along the Dirac cone of a topological insulator and modify its charge transport, but tuning the electronic states and spin-orbit interaction (SOI) without destroying the surface topology is challenging. Here, we show that thin film Bi2Se3/n-p (p-n) molecular diodes form ordered interfaces where charge transfer and orbital re-hybridisation result in a decrease (increase) of the carrier density and improved mobility. In Bi2Se3 the spin-orbit lifetime, t_so, is 0.13 ps, which is comparable to the strongest spin-orbit materials. This lifetime drops further to 0.06 ps (0.09 ps) with the addition of p-n (n-p) molecular diodes, at the limit of measurable values. This strengthened spin-orbit interaction occurs even though molecules are made of light elements and increase the mean free path of the charge carriers by almost 50%, indicating changes to the Berry curvature and/or Rashba splitting around the hybridisation points. Raman spectroscopy gives evidence that the coupling effect may be controlled by optical irradiation, opening a pathway towards the design of heavy-light element hybrids with optically tunable quantum transport.
@article{arxiv.2512.04922,
title = {Tuning the Electronic States of Bi2Se3 Films with Large Spin-Orbit Interaction Using Molecular Heterojunctions},
author = {Matthew Rogers and Craig Knox and Bryan Hickey and Lida Ansari and Farzan Gity and Timothy Moorsom and Mairi McCauley and Gilberto Teobaldi and Manuel dos Santos Dias and Hari B. Vasili and Manuel Valvidares and Mannan Ali and Gavin Burnell and Ahmet Yagmur and Satoshi Sasaki and Oscar Cespedes},
journal= {arXiv preprint arXiv:2512.04922},
year = {2025}
}