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

Takeshi Tayagaki ,Kikuo Makita ,Ryuji Oshima ,Hidenori Mizuno ,Takeyoshi Sugaya

doi:10.1117/1.jpe.8.045503

Abstract

The properties of luminescence coupling (LC) in multijunction solar cells were investigated in three-terminal InGaP//InGaAsP and InGaP/GaAs//InGaAsP tandem solar cells fabricated using the bonding technique through metal nanoparticle (MNP) arrays, where // denotes the mechanical stacking using MNP arrays. Power extraction in the three-terminal tandem solar cells is evaluated, showing that the power extraction in the devices is equivalent to a sum of the power extraction of the top and bottom subcells. In addition, the properties of the LC effect are investigated in the three-terminal tandem devices. The LC current increases with the illuminated light intensity and shows a bias-voltage dependency of the subcell that is emitting luminescence. We also discuss the impact of LC on the power extraction of the three-terminal tandem solar cells.

Highlights

Multijunction solar cells composed from different bandgap semiconductors have achieved higher efficiency compared with conventional single-junction solar cells.[1,2] Dual-junction III–V//Si devices with mechanically stacked, independently operated III–V and Si cells reach cumulative one-sun efficiencies over 30%.3 The efficiency of two-terminal multijunction devices composed of series-connected subcells is reduced by a change in spectral irradiance because the current flow is strictly limited by the minimal current among the subcells
Tayagaki et al.: Analysis of luminescence coupling effect in three-terminal tandem solar cells addition, we investigated the properties of the LC effect in the three-terminal tandem solar cells
Three-terminal tandem solar cells were fabricated through a bonding technique using metal nanoparticle (MNP) arrays.[19]

Summary

Introduction

Multijunction solar cells composed from different bandgap semiconductors have achieved higher efficiency compared with conventional single-junction solar cells.[1,2] Dual-junction III–V//Si devices with mechanically stacked, independently operated III–V and Si cells reach cumulative one-sun efficiencies over 30%.3 The efficiency of two-terminal multijunction devices composed of series-connected subcells is reduced by a change in spectral irradiance because the current flow is strictly limited by the minimal current among the subcells. 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 These techniques can be transferred to develop threeterminal devices, which, have not yet been demonstrated to boost the energy yield for terrestrial use. We discuss the LC effect on the power extraction of the three-terminal tandem solar cells

Sample Preparation

Characterization of the Three-Terminal Tandem Solar Cells

Power Extraction in Three-Terminal Tandem Solar Cells

Luminescence Coupling in Three-Terminal Tandem Solar Cells

Impact of the Coupling Between the Subcells to Power Extraction

Conclusion