Modelling and experimental analysis of the angular distribution of the emitted light from the edge of luminescent solar concentrators

Luminescent solar concentrators (LSCs) have the potential to provide cheap solar electricity by significantly reducing the solar cell area. However, these devices are still at the research level and several aspects of their behaviour need investigation in order to improve efficiencies. Understanding how light is absorbed/emitted and concentrated to the edge of LSCs is required to design a high efficiency device as well as identifying and overcoming the various losses present. One strategy for investigating the photon absorption and transport in LSCs as well as pinpointing the sources of losses in these devices is to look at the luminescence escaping the LSC as a function of angle. This paper presents a new model that reveals the main features of the angular distribution of light escaping a LSC edge. We compare this model with experimental measurements and provide an assessment of non-ideal losses and identify which emission angles are affected most by these losses. We investigated experimentally the effects of the absorption profile of the chromophores and re-absorption on the photon flux travelling at different angles. The effect of back surface reflectors, commonly used to ‘recycle lost photons’, on the edge emission of LSCs has also been investigated in this work.