The use of colloidal quantum dots (CQDs) in advanced optoelectronic devices requires the substitution of bulky long ligands with short organic ligands. The search for a short-ligand that can create stable quantum solids without compromising the confinement of the CQDs is of paramount importance. Within this context, we present a novel surface passivation ligand, benzyl viologene dichloride (BVD-Cl), as a replacement for the conventional trioctylphosphine oxide (TOPO) capping of CdSe CQDs. BVD-Cl enables the creation of a CdSe quantum solid while retaining quantum confinement. To demonstrate the efficacy of this ligand-exchange process, we utilised Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectrometry (EDX), high-resolution transmission electron microscopy (HR-TEM), and X-ray photoemission spectroscopy (XPS). We then implanted the new BVD-Cl:CdSe quantum film as the main inorganic QDs layer into a hybrid photodiode combined with poly 3-hexylthiophene (P3HT) as the organic layer. The photodiode demonstrated high sensitivity to light stimuli and rectifying behaviour, with a responsivity of 70 mA/W at 550 nm. Our observations imply that using BVD-Cl as a surface passivation ligand for CQDs has significant implications for the development of advanced optoelectronic devices.

Peer reviewed