We propose a p-n junction diode based on the adsorption of tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ) molecules on a monolayer of boron phosphide (MBP). We use density functional theory and a simple tight-binding model to investigate atomic configuration, electronic properties, and transport characteristics of the TCNQ/MBP/TTF structure. The p-n mechanism is achieved by the full coverage of MBP with TCNQ and TTF molecules, which are coupled by weak van der Waals forces. The adsorption of each individual molecule on MBP provides localized electronic states close to the valence and conduction bands; this is characteristic of p- and n-type semiconductors. To understand the charge-carrier dynamics, we also examine the evaluation of energy bands, together with localized states, local potential, charge redistribution, and charge transfer under the influence of an external electric field. Our results show that the adsorption of both molecules on the surfaces of MBP results in the behavior of a p-n junction with a rectifying current through the junction in the proposed van der Waals device. Moreover, the optical response to electromagnetic radiation is also analyzed through density functional theory by considering the independent-particle approximation. We show that, with a remarkable absorption band in the infrared region, TCNQ/MBP/TTF is a potential candidate as a component of next-generation optoelectronic devices.

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