The enhancement of photovoltaic efficiency by incorporation of down-shifting phosphor materials in optically active and inactive regions of solar modules is presented. Thin film photovoltaic modules suffer from various optical losses, including front glass reflectance, thermalization loss of absorbed high energy photons, window layer absorption, and the loss of photons to scribe regions. There have been various efforts to improve the performance of solar modules by application of down-shifting (DS), down-converting, and up-converting materials systems. Here we show results towards the development of a low-cost phosphor film system tuned to the solar spectrum and specifically designed for CdTe thin film modules.

The extremely high scintillation efficiency of lutetium iodide doped by cerium is explained as a result of several factors controlling the energy transfer from the host matrix to activator, two of which are investigated in the present paper. The first one is the increase of the efficiency of energy transfer from self-trapped excitons to cerium ions in the row LuCl3-LuBr3-LuI3. The STE structure and the efficiency of STE to cerium energy transfer are verified by cluster ab initio calculations. We propose and theoretically validate the possibility of a new channel of energy transfer to excitons and directly to cerium, namely the Auger process when Lu 4f hole relaxes to the valence band hole with simultaneous creation of additional exciton or excitation of cerium. This process should be efficient in LuI3, and inefficient in LuCl3. In order to justify this channel we perform calculations of density of states using a periodic plane-wave density functional approach. The performed estimations theoretically justify the high LuI3:Ce3+ scintillator yield.

A polyaniline based conducting composite was prepared by oxidative polymerisation of aniline in presence of polyvinylchloride (PVC) matrix. The coherent free standing thin films of the composite were prepared by solution casting method. The PVC-polyaniline composite (90:10) of thickness 40 μm was irradiated with 90 MeV C5+ ions at different ion fluence ranging 5× 1011-5× 1013 ions/cm2. The changes in resistance of pristine and irradiated composite in presence of ammonia gas were studied. A general decrease in surface resistance is observed upon irradiation. The sensitivity, response time and recovery time were studied as a function of ion fluence on exposing the sensor material to ammonia gas at ambient condition. It is observed that irradiated composite films are more sensitive and fast in response to ammonia gas. The preliminary results observed are encouraging.