Development of an instrument for the measurement and warning of dangerous levels of UV-B radiation at recreation grounds

PETE is a new and exciting concept in solar energy research. Whereas in standard photovoltaic applications only the semiconductor band gap can be considered as ‘useful voltage’, in PETE converters a thermal boost (due to the use of concentrated radiation) allows higher operating voltages to provide higher conversion efficiencies. In addition, under conditions of high photon flux, the energy barrier for electron emission is lowered, enabling efficient energy conversion at moderate temperatures that are typically insufficient for ordinary thermionic emission converters. As a result, the combined cycle of a PETE converter and a heat engine might theoretically reach efficiencies above 50% at flux concentration of 1000 suns.

Since PETE is an unexplored concept, little is known on the mechanisms participating in this conversion mechanism. As a result, the upper efficiency limit of this conversion mechanism is yet to be defined. The only PETE model reported to date does not take into account important aspects such as SRH and surface recombination in the semiconductor, spatial variations of charge carrier concentrations and temperature, and many more. Hence, an elaborate model is required in order to determine the PETE conversion efficiency upper limit. An understanding of these issues is essential for the optimal design of a PETE based converter that will achieve the highest conversion efficiencies possible. Additional effects can be considered for increasing conversion efficiencies, such as decoupling of the absorber and emitter areas – shown to improve efficiency in thermophotovoltaic (TPV) and thermophotonic (TPX) devices; the application of an external bias field or the creation of an internal field using a heterojunction; enhancing locally the field at the cathode to enhance electron emission by surface nanostructures. Investigating this wealth of phenomena and potential enhancements requires advanced modelling as well as experimental validation.

Photovoltaic (PV) cells are an efficient mean to convert solar energy into electricity. PV is one of the fastest growing renewable energy sources and shows great promise in countries with enough sun light and in isolated villages. While leading technology is currently silicon based, there is an ongoing effort to find new materials for PV cells. In this research we combine efforts of several experimental and theoretical groups in Israel to do a systematic characterization of a very large set of novel solid state alloys for PV applications. We would initially do theoretical calculations for selected choice of materials and compare our theoretical predictions for the electronic, optical and structural properties to experimental data. At later stages we would initiate high throughput calculations strategies to theoretically predict novel materials (new alloys compositions and new geometrical structures), those predictions are going to be tested by experiment. The experimental setup includes also the formation of nano-crystals and thin films – such structures have properties that are substantially different than the bulk and so an effort would be dedicated to describe also such structures and their possible interfacial effects.

The theoretical and experimental data is going be accessible through a database of properties that would be available to all researchers in the project and later to a wider audience. The main aim of the project is to find new alloys that would allow for cheaper and efficient future PV cells. The project is going to create also a large knowledge base that would have a huge value by itself.