Enhancing concentrator monocrystalline Si solar cells by down conversion Ce3+-Yb3+ co-doped YAG phosphors

Abstract

Down conversion Ce3+-Yb3+ co-doped YAG phosphors are used to enhance concentrator monocrystalline silicon solar cells. The coating of polymethyl methacrylate (PMMA) mixed with the phosphors is deposited on the surface of the solar cells by spin-coating method. It is found that the solar cells with the phosphor coating always have higher conversion efficiency than the bare solar cells under different illumination intensities. This is attributed to the down conversion effect of the phosphors and the reduced reflection (especially in the wavelength range 350–550 nm). The reflection of the light emitted from the phosphor's particles at the air/PMMA interface also contributes to the improvement. The relative growth in the conversion efficiency of the solar cells with the phosphor coatings increases with the illumination intensity from 4.86% under 100 mW cm−2 to 6.04% under 400 mW cm−2 because the increase in the emission from the phosphors is faster than that of the illumination intensity when the illumination intensity increases.

Effective Yellow Y3Al5O12:Ce3+ Nanophosphor for Light‐Emitting Diode and Photovoltaic Cell as a Downconverter

“…As shown in Table 2, few downconversion examples of YAG:Ce bulk (micrometer‐sized) phosphor and film phosphor on photovoltaic cells were reported. [ 10,15–19 ] YAG bulk showed an efficiency increase (Δ η = 0.6%) from 18.68% to 19.28%, and film phosphor with an increase (Δ η = 0.4%) from 17.15% to 17.55%. It is noted that our efficiency enhancement (Δ η = 1.9%) is the record value of all previous results, and in the aspect of reproducibility and reliability, is needed to be carefully reconfirmed later on.…”

“…As shown in Table 2 , some downconversion examples of YAG:Ce bulk (micrometer‐sized) phosphor and film phosphor on photovoltaic cells had been reported. [ 10,15–19 ]…”

Broadband Sensitized Near‐Infrared Quantum Cutting Materials for Silicon Solar Cells: Progress, Challenges, and Perspectives

“…Besides the two possible ET mechanisms above, some researchers have proposed the Ce-O-Yb charge transfer state (CTS) to explain the mechanism of the ET from Ce 3þ to Yb 3þ (Figure 7c). [70] Since the 5d electron of Ce 3þ makes it easier to form a chemical bond with the adjacent O 2À , and the strong electronegativity of Yb makes it easier to bond Yb 3þ and O 2À , it is possible to form Ce-O-Yb CTS. After a 4f electron of Ce 3þ is excited to the 5d energy level, the electron will transit to 2 F 5/2 of Yb 3þ via CTS.…”

“…Then, it relaxes to the bottom of the 5d energy level before emitting a photon. Although near-infrared photons can be emitted through the ET process of CTS, [70,71] this process is not quantum cutting because the material absorbs one highenergy photon while only one low-energy photon can be released. Due to the down-conversion effect, this phosphor enhances the absorption of sunlight by solar cells in the short-wave range (Figure 7a,b).…”

“…Reproduced with permission. [70] Copyright 2018, AIP Publishing. d) Excitation and emission spectra of Ca 3 Al 2 O 6 :Ce 3þ , Yb 3þ , e) emission spectra of Ca 3 Al 2 O 6 :0.01Ce 3þ , xYb 3þ , and f ) luminescence decay curves of Ca 3 Al 2 O 6 :0.01Ce 3þ , xYb 3þ .…”