45-nm CdS QDs photoluminescent filter for photovoltaic conversion efficiency recovery

Authors: VICTOR JUÁREZ-LUNA, DANIEL SAUCEDA-CARVAJAL, IVETT ZAVALA-GUILLEN, ENRIQUE RODARTE-GUAJARDO, FRANCISCO CARRANZA-CHÁVEZ, CARLOS VILLA ANGULO

Abstract: Different energy loss mechanisms have restricted the breakthroughs in concentrated photovoltaic/thermal (CPVT) hybrid solar systems that use photoluminescent filters. Re?ected and transmitted light, emission spectrum, nonideal absorption, Stokes shift (proportional to $f_1 f_2$), overlapping absorption, and scattering of light are mechanisms in photoluminescent filters that restrict optical efficiency to below theoretical limits. In addition, increases in temperature by light concentration affect the operation of photovoltaic cells and photoluminescent filters because of an increase in molecular motion and collisions that consequently lead to energy loss. Meanwhile, nanocrystals or quantum dots (QDs) from groups II VI hold electrical, optical, chemical, and physical properties that can be used to mitigate the aforementioned limitations. In this study, cadmium sulfide QDs with a diameter of 45 nm and absorption and photoluminescent spectra centered at 480 and 600 nm, respectively, were deposited in a soda-lima glass to obtain a 200-nm-thick film photoluminescent filter. The photoluminescent filter was matched to a silicon solar cell and used as an electrical power efficiency recovery filter in a hybrid CPVT solar system. A recovery of electrical power conversion efficiency higher than 3.1\% at temperatures greater than 100$^{\circ}$C was theoretically predicted and practically confirmed. A predicted trend of increases in recovered electrical power parameters as temperature increases was also verified.

Keywords: Concentrated photovoltaic/thermal hybrid solar systems, photoluminescent filter, CdS quantum dots, Si-based solar cell

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