Performace of Dilute Nitride Triple Junction Space Solar Cell Grown by MBE

Arto Aho,Riku Isoaho,Marianna Raappana,Antti Tukiainen,Ville Polojärvi,Mircea Guina,Timo Aho,A Fernandez

doi:10.1051/e3sconf/20171603008

Abstract

Dilute nitride arsenide antimonide compounds offer widely tailorable band-gaps, ranging from 0.8 eV to 1.4 eV, for the development of lattice-matched multijunction solar cells with three or more junctions. Here we report on the performance of GaInP/GaAs/GaInNAsSb solar cell grown by molecular beam epitaxy. An efficiency of 27% under AM0 conditions is demonstrated. In addition, the cell was measured at different temperatures. The short circuit current density exhibited a temperature coefficient of 0.006 mA/cm 2 /°C while the corresponding slope for the open circuit voltage was −6.8 mV/°C. Further efficiency improvement, up to 32%, is projected by better current balancing and structural optimization.

Highlights

Commercial space solar cells have reached 30% beginning of life (BOL) efficiencies [1]
Projective calculations based on diode modelling and the measured performance of dilute nitride cells have shown that for realistic GaInP/GaAs/GaInNAsSb design, the BOL efficiency could increase approximately 3 percentage points when compared to a Ge-based cell [3]
We demonstrate a triple junction GaInP/GaAs/GaInNAsSb solar cell grown by molecular beam epitaxy (MBE), which sets a roadmap towards demonstrating higher efficiencies and solar cells incorporating higher number of junctions

Summary

INTRODUCTION

Commercial space solar cells have reached 30% beginning of life (BOL) efficiencies [1]. In lattice matched GaInP/GaInAs/Ge cell the spectral range from 0.7 eV to 1.4 eV is covered by the Ge sub-junction. In this case, there is a high overall quantum defect between photon energies and the band-gap energy of Ge leading to inefficient energy conversion. Lattice matched 1 eV band-gap dilute nitrides, such as GaInNAsSb alloys, offer lower quantum defect and higher voltage generation. Projective calculations based on diode modelling and the measured performance of dilute nitride cells have shown that for realistic GaInP/GaAs/GaInNAsSb design, the BOL efficiency could increase approximately 3 percentage points when compared to a Ge-based cell [3]. We demonstrate a triple junction GaInP/GaAs/GaInNAsSb solar cell grown by molecular beam epitaxy (MBE), which sets a roadmap towards demonstrating higher efficiencies and solar cells incorporating higher number of junctions

EXPERIMENTS

RESULTS AND DISCUSSION

CONCLUCION AND FUTURE WORK