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RESEARCH PRODUCT

Role of Self-Absorption in the Photoluminescence Waveguided along CsPbBr3 Perovskite Nanocrystals Thin Films

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During the last years, perovskite nanocrystals (PNCs) have been intensively studied as nanomaterials with excellent light absorption/emission properties. For example, PNCs have been successfully applied in solar cells, where the high absorption coefficient above the band gap increases the conversion efficiencies; or in optical sources, where the high quantum yield of emission at room temperature allows a low threshold of stimulated emission. In this scenario, an optical waveguide represents a suitable platform to enhance their electrooptical properties and to integrate different photonic functionalities. However, propagation of light along close packed films of PNCs is usually restricted to $\sim 10\ \mu \mathrm{m}$ due to the high absorption efficiency above the bandgap and the scattering losses. In this work, we present an elegant integration of CsPbBr3 PNCs in polymer waveguides that allows high generation of light together with propagation along long distances. In particular, we propose an ultrathin layers (50–100 nm) of close packed CsPbBr 3 PNCs sandwiched between two poly(methyl methacrylate) (PMMA) slabs. This configuration efficiently enhances the absorption and emission properties of the PNCs by the high confinement of the electromagnetic field within the active layer and allows the propagation over longer distances due to the absence of losses in the polymers. Since our experimental data reveals that light amplification threshold on this material only depends on the reabsorption, geometrical parameters in our structure are properly optimized to enhance the generation of light. These results provide a novel knowledge on the possible use of CsPbBr 3 inside waveguides and can pave the road of new optoelectronic devices based on PNCs.