The ability to effectively capture the incident sunlight radiation presents one of the grand challenges of photovoltaics today [1]. A variety of existing solar cells rely on efficient light trapping to enhance optical absorption. This can be achieved by surface texturing which can increase light absorption and reduce the thickness of solar cells [2]. A novel method has been developed for efficient photon management where the frequency is changed between absorption of the incident light and its re-emission as fluorescence [3]. A similar idea is to employ a photon management structure to maximize the photon path length inside the solar cell and obtain a novel form of optical confinement, or light trapping when compared to the traditional scheme based on surface texturing.

We have prepared absorbing/fluorescent dye layers based on Langmuir-Blodgett films and spin coated perylene dyes which have been shown to be suitable for light harvesting [4]. Optical characterisation of the dye layers was carried out using absorption and fluorescence spectroscopy and the trapping efficiencies were calculated using an integrated sphere and conductivity measurements. We apply the optimised dye structure on a wafer bonded crystalline silicon layer on glass of only 200 nm thickness and estimate the increase in light trapping efficiency.

References
1. T. Markvart, L. Danos, L. Fang, T. Parel and N. Soleimani, RSC Adv., 2012, 2,
3173.
2. E. Yablonovitch and G. D. Cody, IEEE Trans. Electron Dev. 1982, ED-29, 300.
3. T. Markvart, Appl. Phys. Lett., 2011 98, 071107.
4. L. Danos and T. Markvart, Chem. Phys. Lett., 2010, 490, 194.