The photonic luminescent solar concentrator (LSC), a flat light-refocusing device, has been proposed as a solution to unlock low-cost, high efficiency solar modules because of its potential to achieve concentrations much higher than traditional lenses [1]. Further, because of the inherent wavelength selectivity of the structure, using multiple wavelength LSCs could finally enable spectrum-splitting designs wherein the broadband solar spectrum is demultiplexed onto multiple bandgap cells (multijunction cell), enabling efficiencies exceeding 50% [2]. Here, we explore how the unique surface sensitivity of perovskite nanocrystals can be exploited to significantly increase the light trapping in LSC designs. Inorganic lead halide perovskites (CsPbX3(X=halide)) have exhibited remarkable optical properties that make them well suited for LSCs, such as high quantum yields [3]. Further, the transition dipole moment of perovskite nanocrystals (governs directional emission) is highly controllable based on local environment [4]. We show how using bilayers of perovskite nanoparticles can enhance directional emission of perovskites for use in LSCs. UV-vis spectroscopy quantifies spectral interaction of these layers and TEM imaging shows particle packing and alignment. Films are characterized via back focal plane (Fourier) imaging, which quantifies the angle-resolved light emission pattern. Preliminary results show that 270 nm thick films of CsPbBr3 cubes (emission = 515 nm) emit light randomly, while 270 nm thick films of CsPbB3 cubes on top of a layer of CsPbBr3 nanoplates (emission = 450 nm) have a higher dipole angle (40°), favoring total internal reflection modes. This change in alignment results in a trapping improvement of 4% [5].
|