Determination of the complex refractive index of powder phosphors

Abstract

Abstract:We demonstrate a novel 2-step method to precisely determine both n and k of phosphors, luminescent inorganic particles, in the visible spectrum. To measure n we modified the Becke Line immersion method and verified its applicability in the absorption/ emission regions of phosphor particles (step 1). Particles were then embedded into a transparent binder and coated in thick layers (100-500 µm) on glass. Absorptance of the layers was measured with a novel approach: spectral angular resolved measurements. This method delivers accurate results by avoiding any errors from intense scattering inside the layers. A computational model was employed to extract k of particles from the measured absorptance data taking into account luminescence, scattering and re-absorption (step 2). The entire method was verified on reference materials. Finally, based on the proposed method, we determined in a broad wavelength range the n and k parameters for a variety of commonly used phosphors with few or no earlier reports on their n and k values (the complete set of numerical data is fully disclosed in the supplementary materials). 10. S. Pimputkar, J. S. Speck, S. P. DenBaars, and S. Nakamura, "Prospects for LED lighting," Nat. Photonics 3(4), 180-182 (2009 4502-4514 (2006). 13. J.-P. Moy, "Recent developments in X-ray imaging detectors," Nucl. Instrum. Methods Phys. Res. 442(1-3), 26-37 (2000). 14. L. Wondraczek, M. Batentschuk, M. A. Schmidt, R. Borchardt, S. Scheiner, B. Seemann, P. Schweizer, and C. J.Brabec, "Solar spectral conversion for improving the photosynthetic activity in algae reactors," Nat. Commun. 4, 2047Commun. 4, (2013 based on a demonstrated cross-relaxation process," Sci. Rep. 6(1), 22545 (2016).

Improving Light Absorption in a Perovskite/Si Tandem Solar Cell via Light Scattering and UV‐Down Shifting by a Mixture of SiO2 Nanoparticles and Phosphors

“…However, as the volume concentration of SGA increases, the PCE of the device decreases. This is because the higher refractive index ( n ≈ 1.7–1.9) [ 21 ] and larger size (≈5 µm in diameter) of SGA decreases the total transmittance (Figure 2b). Since the size of SGA particles is larger than the wavelength of incident light, SGA also contributes to increase the backward scattering at the SGA–PDMS interface and decreasing the diffuse transmittance (Figure 2c).…”

Estimating the performance of solar cells with luminescent down-shifting layers

“…Using values of n and k as a function of wavelength for each of the materials [15-17] that constitute the CdTe device (see figure 2), the R(λ) and T(λ) calculation were made using an optical matrix method [13,14], as mentioned above. For the Lu 3 Al 5 O 12 :Ce 3+ LDS layer, the n(λ) and k(λ) spectra, as reported by other authors, were used [18,19].…”

Absorption and Remission Characterization of Pure, Dielectric (Nano-)Powders Using Diffuse Reflectance Spectroscopy: An End-To-End Instruction

“…Ray tracers (e.g., LightTools [166,167]) allow accurate simulation of light-matter interaction at surfaces. Provided the number of rays is sufficiently large, statistical processes such as the diffuse reflectance can also be approximated satisfactorily [146,[168][169][170][171][172][173][174][175][176][177][178][179][180][181]. For this, a model of the material under investigation is designed; relevant physical parameters that will be used within the simulation are determined beforehand such as the refractive index, e.g., via the Becke line or Schroeder van der Kolk method [182][183][184][185][186], or the particle size distribution q 0 , e.g., via disc centrifugation [159].…”