Environmental friendly narrow band-gap colloidal nanocrystals for optoelectronic devices
In recent years a widespread investigation of semiconductor materials and its use in optoelectronic devices has taken place. Despite the vast variety of semiconductor materials, solution processable semiconductor nanocrystals (NC’s) take lead thanks to their excellent optoelectronic properties (tunable band-gap, high PLQY and optical stability) while they become more and more appealing for their low production cost. Although, a variety of semiconductor NC’s have been synthesized for application in the visible spectral region, only few examples exist with tunability in mid and near-IR, and most notable high toxicity mercury and lead based NCs. On the other hand, nowadays we experience a burst of emerging near and mid-IR technologies (e.g. solar cells, detectors, night cameras) which are moving towards the use of environmentally friendly IR emitting materials for large scale production. Therefore, NAROBAND aims to exploit the synthesis and the functionalization of low-toxic narrow-band gap Ag2SxSey NC’s via both chemical and physical routes towards the fabrication of environmental friendly, low cost solar cell devices. The project focus on achieving full control of the bandgap (1.2eV–0.4eV) via quantum confinement and stoichiometry allowing to decouple nanocrystals size and surface effects from bandgap, leading to a better control of the optoelectronic properties. Moreover, throughout careful surface characterization and functionalization NAROBAND aims to suppression of the trap state density, enhancing the carrier mobility and manipulating the energy levels of the valence and conduction band of the NC’s. These material advancements will pave the way towards, firstly, the fabrication of high efficient IR solar cell devices and later on the realization of tandem solar cell by using the conventional Si technology to harvest the high energy electromagnetic radiation of the sun, while the aforementioned solar cell device will collect the, so far wasted, IR radiation.