High-Efficiency Monolithic Three-Terminal GaAs/Si Tandem Solar Cells Fabricated by Metalorganic Chemical Vapor Deposition

Abstract

A monolithic GaAs/Si tandem solar cell which consists of a p+-n GaAs top cell and an n+-p-p+ Si bottom cell is fabricated by metalorganic chemical vapor deposition. The conversion efficiency of the top cell is increased by improvement of the solar cell structure (adoption of a graded band emitter layer) and optimization of the growth conditions (increase of the thermal annealing temperature and the growth temperature). By combining the conversion efficiencies of the GaAs top cell (16.0%) and Si bottom cell (3.9%), the active-area conversion efficiency of 19.9% (AM0, 1 sun) has been obtained in the three-terminal configuration.

Back‐contacted bottom cells with three terminals: Maximizing power extraction from current‐mismatched tandem cells

“…The model introduced so far (with R IBC = 0 and R FB = 0) in Figure 6A is intuitive and therefore commonly used for mid-contacted 3T tandem solar cells, 25,28,34,35,39 as shown in Figure 6B,C (with R IBC = 0 and R FB = 0). The BJT solar cell, which has the same architecture as reported earlier by several authors, [25][26][27][28][29][30][31][32][33][34][35][36]41 was modeled by Martí and Luque using Ebers-Moll model 54 and turns out to be still describable by Figure 6C (without resistors). Figure 6B and 6C).…”

“…24 A less common approach, the three-terminal (3T) tandem cell with a middle electrode ( Figure 1D), has been proposed by several authors for different combinations of subcells. [25][26][27][28][29][30][31][32][33][34][35][36][37][38] While several publications utilize the 3T device to probe and match the currents of 2T tandems, almost all of them recognized that adding a third mid-contact to a 2T tandem eliminates the need for current-matching. A mid-contacted 3T tandem enables a monolithic tandem solar cell, which combines the monolithic design of 2T tandems and the flexibility of 4T tandem cells.…”

Analysis of luminescence coupling effect in three-terminal tandem solar cells

“…Three-terminal tandem solar cells, developed by adding a third electrode into the two-terminal tandem solar cells, have also been considered as a plausible approach to maximize power extraction. 7 The three-terminal devices can adjust the current mismatching between the subcells and obtain robustness against the change of spectral irradiances. So far, the benefits of a threeterminal design have been investigated using device physics simulation.…”

“…12 In contrast to many model calculations, the literature is lacking in the experimental proof of three-terminal tandem solar cells. Monolithic three-terminal tandem solar cells have been fabricated by metalorganic chemical vapor deposition, 7,13 showing an active-area conversion efficiency of 19.9% in a three-terminal GaAs/Si configuration. 7 In addition, the integrated module of three-terminal devices using voltage matching circuit 14 can perform as well as the independent operation of the top and bottom cells.…”

“…Monolithic three-terminal tandem solar cells have been fabricated by metalorganic chemical vapor deposition, 7,13 showing an active-area conversion efficiency of 19.9% in a three-terminal GaAs/Si configuration. 7 In addition, the integrated module of three-terminal devices using voltage matching circuit 14 can perform as well as the independent operation of the top and bottom cells. 15 The recent progress in wafer bonding 16 and mechanical stacking 17,18 has opened up new approaches for fabricating highly efficient three-terminal tandem solar cells with high crystal quality.…”