Novel luminescent solar concentrator utilizing stimulated emission

Abstract

Luminescent Solar Concentrators (LSCs) are an emerging technology that aims primarily to reduce the cost of photovoltaic (PV) power generation, with great potential for building-integrated photovoltaics (BIPV) system. Commercial realization of these devices is mainly hampered by reabsorption loss. This work describes a novel method of reducing the reabsorption as well as improving the directional emission utilizing stimulated emission, rather than only spontaneous emission as in standard LSCs, by using a seed laser. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire area of the LSC panel, modifying the emission spectrum of the photoexcited luminophores such that it is spectrally narrower, at a wavelength that minimizes reabsorption and allows a net gain in the system, and is directed towards a small PV cell, anticipated to be ~ 1 mm2. A fraction of the PV cell’s output power is fed back to the seed laser; i.e. the system acts as a closed loop system. This thesis reports the design and working principle of a stimulated-LSC (s-LSC) and the development of a mathematical model to identify important physical parameters for the practical realization. Also, a novel method to characterize the luminophores for the s-LSC system is developed using a parameter called ‘stimulated gain coefficient.' Finally, this concept has been explored with the known photostable Perylene Red (PR) dyes for the proof of principle. The experimental results are well-matched with the model except for the gain saturation with a comparatively small seed laser signal power. To investigate this gain saturation, two approaches were taken: investigating (i) spectral hole burning and (ii) triplet state absorption. None of the existing luminophores investigated show the required characteristics for the s-LSC system. However, there is a plenty of room for the innovation of luminophores to realize a practical s-LSC system.