Recent Advances in Luminescent Downconversion: New Materials, Techniques, and Applications in Solar Cells

Abstract

Numerous investigations have been done in pursuing phosphors with quantum yield (QY) greater than unity in terms of downconversion (DC) strategies, as well as applications in display, lighting, and particularly in novel solar cells with efficiency exceeding the Shockley–Queisser limit (≈30%). It is of significant interest that: i) DC of one high‐energy photon to two or more low‐energy photons is widely found in lanthanide and/or transition‐metal ions activated materials; ii) broadening of absorption spanning ultraviolet/blue range is achieved by introducing sensitizers with spin‐allowed transitions and especially by combining the advancing perovskite quantum dots, nanostructures, and organic dye molecules; iii) internal QY ≫ 1 and even measured QY > 1 are claimed in many near‐infrared (NIR) DC systems; iv) applications of downconverting layer atop commercial solar cells are performed to increase the photon conversion efficiency. In this review, the development of DC in theories, concepts, and experiments is first summarized, then the breakthrough in visible‐DC is briefly highlighted, NIR‐DC with latest progresses in models, materials, techniques as well as the corresponding optimizations and practices as effective downconverting layers is elaborated, and finally concluding remarks and perspectives in advancing NIR‐DC and applications in novel solar cells are given.

Superior thermal cycling stability of a carbon dots@NaBiF4 nanocomposite: facile synthesis and surface configurations

“…Therefore, it is worthwhile to study the feasibility of the Ln ion doping strategy to improve the QY in future, which may promote its potential applications in multi-imaging. 36…”

Optical Coupling Efficiency, Photon Loss, and Efficiency Estimates for c-Si PERC Modules Enhanced with Downconverting Films and Nanocomposites

“…Experimentally, downconversion is achieved by doping or codoping trivalent lanthanide ions (Ln 3+ ) to activate host materials such as phosphors, glass, ceramics, and nanocrystals. − Ln 3+ ions have ladder-like energy-level structures that achieve quantum cutting through resonant cross-relaxation processes or multistep cascade radiative transitions . Recent work on Yb-doped CsPb­(Cl 1– x Br x ) 3 , for example, has demonstrated high quantum yields of up to 195%, strong blue and UV absorption, and narrow PL around 1000 nm where the Si quantum efficiency is high. ,− The band edge is tunable from 400 to 500 nm by manipulating the chloride-to-bromide ratio, which provides more flexibility for optimization in photovoltaic systems. , Previous detailed balance studies for this perovskite material predict that the downconversion can increase the power conversion efficiency for multicrystalline-Si, CIGS, and Si heterojunction solar cells by absolute percentages of 3.5, 4.2, and 5.3% …”

“…7−9 Ln 3+ ions have ladder-like energy-level structures that achieve quantum cutting through resonant cross-relaxation processes or multistep cascade radiative transitions. 8 Recent work on Yb-doped CsPb(Cl 1−x Br x ) 3 , for example, has demonstrated high quantum yields of up to 195%, strong blue and UV absorption, and narrow PL around 1000 nm where the Si quantum efficiency is high. 4,9−11 The band edge is tunable from 400 to 500 nm by manipulating the chloride-tobromide ratio, which provides more flexibility for optimization in photovoltaic systems.…”

In Situ Generating YVO4:Eu3+,Bi3+ Downshifting Phosphors in SiO2 Antireflection Coating for Efficiency Enhancement and Ultraviolet Stability of Silicon Solar Cells

“…To broaden the spectral response of c-Si solar cells, spectral conversion has been widely studied and developed as a promising technology. [12] Luminescence downconversion (including downshifting and quantum cutting) materials, which can absorb high-energy ultraviolet (UV) photons and emit low-energy photons at long wavelengths, can simultaneously improve the conversion efficiency of solar cells or modules [13,14] and enhance their UV stability, [15,16] thus attracting more attention. In addition to causing the aging of module packaging materials, [17] UV irradiation can degrade the electrical performance of solar cells.…”