Nanomaterials applied to Optoelectronics and photovoltaic applications

Cu3N has been introduced as a new class of materials for new generation photovoltaic and photocatalysts applications due to its high absorption light, good electrical properties, high potential realization of p-n homojunctions and highly defect-tolerant semiconductor. The most attractive characteristic feature of Cu3N is its indirect band gap energy ad its optical absorption coefficient, which is ideal for highly efficient delivery and separation of photo-generated carriers. The transition metal nitrides can reduce the overpotential or activation energy for photocatalytic reactions on the surface of semiconductors by providing extra active sites, and promote the electron–hole separation. However, concerning improve the photocatalytic efficiency, a lot of modifications studies have been done in order to broaden the wavelength range of light that effectively functions, improve the separation of excited charges, and inhibit the recombination of photogenerated carriers.

We are investigating potential carbon based hybrid nanocomposites to produce photocurrent under visible light and UV light excitation. Our recent investigations have shown that it is possible to obtain photocurrent production by combining HfO2 nanoparticles with multi-walled carbon nanotubes. The other nanoparticles coupled with CNT are ZnO and Ag nanoparticles. Both HfO2 and ZnO when combined with CNT produce a photocurrent however, the origin of these photo-generated charges are quite different as one is a dielectric while the other is a wide band gap semiconductor. In both cases surface defects play an important role is photocurrent generation.

List of relevant publications:

Research project partially funded by the Estonian Centre of Excellence 2015 EQUiTANT (TK134), and EMÜ Bridge Funding (P200030VLVB) .