Anisotropic luminophore emission for enhanced light trapping in luminescent solar concentrators

Building-integrated photovoltaic (BIPV) technologies integrate photovoltaic energy generation into the design of semi-transparent and opaque building envelopes. The photovoltaic luminescent solar concentrator (LSC) is an example of such a technology and offers the potential for low-cost, passive concentration of direct and diffuse light. Recent advances in the emission efficiency of semiconductor luminophores could significantly reduce parasitic losses, but efficient light trapping remains elusive to achieve high conversion efficiency LSCs. Here, we demonstrate anisotropic luminophore emission to enhance light trapping in the LSC waveguide. By embedding semiconductor nanoplatelet emitters into high-index TiO2 nanocylinders, we alter their angular emission profile to increase emission into total internal reflection (TIR) angles. The emission direction can be controlled by tweaking Mie-like multipolar resonances in the individual nanocylinders (form factor) and the interaction with the lattice (structure factor). Angle-resolved photoluminescence measurements on the fabricated nanocylinders arrays corroborate this understanding. By optimizing the cylinder shape and lattice spacing, we show an increase in light trapping from 75% (isotropic emission) to 83.5%. This novel approach to the integration of nanoscale photonic structures and emitters paves the way for enhanced emission control in photovoltaic systems, as well as in solid-state lighting and smart displays.