Direct evaluation of influence of electron damage on the subcell performance in
triple-junction solar cells using photoluminescence decays
#MMPMID28512330
Tex DM
; Nakamura T
; Imaizumi M
; Ohshima T
; Kanemitsu Y
Sci Rep
2017[May]; 7
(1
): 1985
PMID28512330
show ga
Tandem solar cells are suited for space applications due to their high
performance, but also have to be designed in such a way to minimize influence of
degradation by the high energy particle flux in space. The analysis of the
subcell performance is crucial to understand the device physics and achieve
optimized designs of tandem solar cells. Here, the radiation-induced damage of
inverted grown InGaP/GaAs/InGaAs triple-junction solar cells for various electron
fluences are characterized using conventional current-voltage (I-V) measurements
and time-resolved photoluminescence (PL). The conversion efficiencies of the
entire device before and after damage are measured with I-V curves and compared
with the efficiencies predicted from the time-resolved method. Using the
time-resolved data the change in the carrier dynamics in the subcells can be
discussed. Our optical method allows to predict the absolute electrical
conversion efficiency of the device with an accuracy of better than 5%. While
both InGaP and GaAs subcells suffered from significant material degradation, the
performance loss of the total device can be completely ascribed to the damage in
the GaAs subcell. This points out the importance of high internal electric fields
at the operating point.
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