AM0 Optimized Dual Junction Quantum Well Solar Cells-Investigation of Radiation Tolerance Designs and Voc Retention at EOL

Dual junction upright solar cells composed of a homojunction GaInP top cell and a heterojunction GaInP/GaAs bottom cell incorporating 50 layers of Ga
0.9
In
0.1
As quantum wells (QWs) with GaAs
0.9
P
0.1
barriers and a 12-pair Al
0.9
Ga
0.1
As/Al
0.1
Ga
0.9
As distributed Bragg reflector were designed for operation under AM0 and grown by MOVPE. Performance degradation was investigated after irradiance of 1 MeV electrons at a fluence of 1 x 10
¹⁵
cm
⁻²
, revealing a Jsc remaining factor of 0.933 in the device with 50 pairs of QWs compared to 0.854 in the 0 QW control. In addition to a 1.7% absolute AM0 efficiency increase in the QW device relative to the control, Voc and fill factor remaining factors were held above 0.86 in both devices, producing equivalent EOL efficiencies of 18%. Modifications to layer and interface designs surrounding the quantum well region will be investigated in an effort to improve EOL V
oc
and FF in the quantum well device. IV performance under AM0 illumination, layer-specific current collection degradation in the GaAs sub-cell, and sub-cell saturation current densities will be investigated. The device design presented in this work is compatible with the current state-of-the-art GaInP/GaAs/Ge triple-junction architecture. With continued optimization of both subcells, a path to 2J efficiency under AM0 surpassing 27% BOL and 21% EOL may be realized.