Modeling and design for low‐cost multijunction solar cell via light‐trapping rear texture technique: Applied in InGaP/GaAs/InGaAs triple junction

Abstract

To realize high efficiency in parallel with low cost, a light‐trapping rear texture was proposed to be implemented in substrate‐free thin‐film multijunction (MJ) cells. A detailed‐balance theory was formulated taking account of the finite light absorption in thin subcells. Such presented absorption model is general and useful to optimize the subcell thickness for MJ solar cells with light‐trapping design. It is applied for InGaP/GaAs/InGaAs triple‐junction solar cells to simulate subcell photocurrents and to obtain the current‐matching (minimum requisite) subcell thicknesses combinations. Furthermore, the detailed‐balance conversion efficiency was estimated for both radiative limit and the cases with below‐unity internal radiative efficiency. For InGaP/GaAs/InGaAs MJ cells with InGaP subcell thickness less than 600 nm, adding a random‐textured rear reflector can enhance light absorption so significantly that over 90% of InGaAs‐cell thickness and even 50% of GaAs‐cell thickness would be cut without any penalty in conversion efficiency, compared with the subcell thicknesses in traditional MJ cells with flat rear reflectors. Additionally, the thickness combination, (InGaP, GaAs, and InGaAs) = (450 nm, 333 nm, and 26 nm), is recommended to achieve both high conversion efficiency and low material cost. This work provides a very important theoretical guidance for the development on low‐cost and high‐efficiency MJ devices.

Stress Analysis of Flexible GaInP/GaAs/InGaAs Solar Cells Based on Cu Thin‐Film Substrates

“…GaInP/GaAs/InGaAs solar cells have an initial curvature, which is mainly caused by the lattice mismatch of the InGaAs bottom cell. [ 19 ] So we first measured strain relaxation of the GaInP/GaAs/InGaAs solar cells using high‐resolution X‐ray diffractometer RSM. After that, we electroplated different thicknesses of Cu film on GaInP/GaAs/InGaAs solar cells.…”

Hotspots, frontiers, and emerging trends of tandem solar cell research: A comprehensive review

“…Solar cells achieve efficient optical management and increase light capture by light trapping, leading to the PCE improvement of PV cells. [48][49][50] It is significant that Light trapping is introduced in TSC research and becomes one of top 10 research clusters (#7).…”

Light‐trapping and spectral modulation to increase the conversion efficiency of triple‐junction GaAs solar cells using antireflective coating comprising a periodic array of cone‐shaped TiO 2 structures

“…Current matching among sub-cells can be achieved by tailoring the bandgap energy and thickness of individual sub-cells to optimize light absorption in specific wavelength bands. [22][23][24][25][26][27] Unfortunately, process variation during the epitaxial growth stage makes it difficult to match current perfectly among all sub-cells. Multilayer anti-reflective coatings with graded-index, refractive index, or high-low refractive index could conceivably be used to distribute light among sub-cells.…”

“…The output photocurrent of monolithically‐integrated cells is limited by the sub‐cell with the lowest current generation capability as well as by overall conversion efficiency. Current matching among sub‐cells can be achieved by tailoring the bandgap energy and thickness of individual sub‐cells to optimize light absorption in specific wavelength bands 22‐27 . Unfortunately, process variation during the epitaxial growth stage makes it difficult to match current perfectly among all sub‐cells.…”