2D layering of silicon nanocrystals at TiO2/CuI heterojunction for enhanced charge transport

Abstract

We prepared a two-dimensional layer of silicon nanoparticles at the CuI/TiO2 p-n junction heterophase interface by spray coating of colloidal ink of nanoparticles. The particles are prepared by a physical process of milling at room temperature and further etched to obtain a nanometric size distribution with a mode at ∼2 nm. These particles at the interface act as traps for electrons. However, the traps fill up quickly in a diode configuration due to the dense band structure of the nanoparticles, and overflowed electrons can tunnel through the junction, thereby significantly increasing the efficiency as reflected by a large increase in the diode current. A qualitative model is developed in terms of discrete band states at the interface to explain the above phenomena. The results offer opportunities for developing high-performance semiconducting devices.