Upconverter Silicon Solar Cell Devices for Efficient Utilization of Sub-Band-Gap Photons Under Concentrated Solar Radiation

Photochemical upconversion: present status and prospects for its application to solar energy conversion

“…One of the most efficient UC phosphors to date is NaYF 4 , doped with Er 3+ or co-doped with Yb 3+ and Er 3+ , which was introduced in 1972 by Menyuk et al 74 Comprehensive reviews of ETU by f -shell ions in solid bulk matrices and nanoparticles include the works by Auzel 11 and Haase et al 75 The first realization of an upconversion-assisted solar cell was based on Yb 3+ and Er 3+ ions in a vitroceramic host, placed behind a GaAs solar cell. 76 The first application of the same system to c-Si solar cells was demonstrated in 2005 by Shalav et al, 13,77 and current lanthanoid-based upconversion efforts are mainly focused around crystalline silicon, 14,[78][79][80] due to the energetically favorable absorption of Er 3+ around 1523 nm, below the c-Si band edge in energy and within a local maximum of the solar spectral irradiance. 12 Currently, the most efficient lanthanoid upconversion phosphor for c-Si PV applications appears to be β -NaYF 4 :20-25%Er 3+ powder.…”

A review of concentrator silicon solar cells

“…But the efficiency of the luminescent concentrator system was still low compared to traditional optical concentrator system, the highest efficiency was just 7.1% under 2.5 suns using GaAs cells [17,37]. The upconverter materials could be placed at the bottom of the bifacial illuminated cell under concentration, these materials can absorb the light which could not be absorbed by silicon and emit the light with shorter wavelength which could be absorbed by silicon to the back surface of the cell [38,39]. Above optical concentrator and luminescent concentrator elements could be used together, Arnaoutakis et al added compound parabolic concentrator to the upconverter materials which was placed at the bottom of the cell, it increased the efficiency of the cell from 0.123% to 0.163% under 0.024 W/cm 2 illumination of 1523 nm light [38].…”

“…8, local contact structure was used, the front and back surfaces of the cell were made planar, the front and back antireflection layers were optimized to transmit the sub-bandgap photons to the bottom upconverter materials and to decrease the back surface reflection of the light emitted by upconverter materials around 980 nm [63]. Fischer et al placed BaY 2 F 8 and NaYF 4 upconverter materials to the bottom of the bifacial illuminated cell under concentration, these materials absorbed the light around 1500 nm and emitted the light around 980 nm, the short circuit current of the cell increased 17.273.0 mA/cm 2 under 94 717 suns using BaY 2 F 8 upconverter materials [64], and it increased 13.1 mA/cm 2 under 210 suns using NaYF 4 upconverter materials [39]. Above cells were made by CMOS-like semiconductor process or industrial crystalline silicon solar cell manufacturing process, the PN junctions of above cells were mainly made by diffusion, the front surface was covered by passivation and antireflection layer, and the grids were made by evaporation, plating or screen printing technology.…”

Rare earths and metal nanoparticles in silicate glass-ceramics to improve the efficiency of photovoltaic solar cells

“…In down-conversion, multiple low-energy photons are generated to exploit the energy of one incident high-energy photon. In up-conversion, two or more incoming photons generate at least one photon with a higher energy than the incoming photons [5][6].…”