On improving the short-wavelength response and efficiency of photovoltaic modules via luminescent down-shifting of the incident light

This thesis investigates the technology of luminescent down-shifting (LDS) of light for improving the short-wavelength response and efficiency of photovoltaic (PV) modules. A critical literature review of previously published work is presented identifying the opportunity to include the luminescent species in the encapsulation layer of certain PV technologies. A range of luminescent materials and mixtures thereof were tested in ethylene vinyl acetate (EVA) host. They all exhibited very high luminescent efficiencies and did not impair the transmittance of the encapsulant. LDS EVA sheets were used to encapsulate multi-crystalline silicon (mc-Si) and chalcopyrite (CIGS) solar cells. An increase in short-λ external quantum efficiency of up to 25 % was achieved for mc-Si devices. For CIGS, the increase was up to 25 % and 40 % for 50-nm- and 100-nm-thick buffers respectively. The overall efficiency of mc-Si devices was improved by 0.2 % in the best case and gains of up to 0.2 mA / cm2 and 0.6 mA / cm2 were achieved for 50-nm- and 100-nm-thick buffer CIGS devices. LDS offers the additional benefit of device colouration, which can encourage the further uptake of PV in applications where colour is a desirable property

Multiscale in modelling and validation for solar photovoltaics

Photovoltaics is amongst the most important technologies for renewable energy sources, and plays a key role in the development of a society with a smaller environmental footprint. Key parameters for solar cells are their energy conversion efficiency, their operating lifetime, and the cost of the energy obtained from a photovoltaic system compared to other sources. The optimization of these aspects involves the exploitation of new materials and development of novel solar cell concepts and designs. Both theoretical modeling and characterization of such devices require a comprehensive view including all scales from the atomic to the macroscopic and industrial scale. The different length scales of the electronic and optical degrees of freedoms specifically lead to an intrinsic need for multiscale simulation, which is accentuated in many advanced photovoltaics concepts including nanostructured regions. Therefore, multiscale modeling has found particular interest in the photovoltaics community, as a tool to advance the field beyond its current limits. In this article, we review the field of multiscale techniques applied to photovoltaics, and we discuss opportunities and remaining challenges

Towards Efficient Spectral Converters through Materials Design for Luminescent Solar Devices.

Single-junction photovoltaic devices exhibit a bottleneck in their efficiency due to incomplete or inefficient harvesting of photons in the low- or high-energy regions of the solar spectrum. Spectral converters can be used to convert solar photons into energies that are more effectively captured by the photovoltaic device through a photoluminescence process. Here, recent advances in the fields of luminescent solar concentration, luminescent downshifting, and upconversion are discussed. The focus is specifically on the role that materials science has to play in overcoming barriers in the optical performance in all spectral converters and on their successful integration with both established (e.g., c-Si, GaAs) and emerging (perovskite, organic, dye-sensitized) cell types. Current challenges and emerging research directions, which need to be addressed for the development of next-generation luminescent solar devices, are also discussed.This work was supported by the Science Foundation Ireland under Grant No. 12/IP/1608