Open AccessCharge separation in subcells of triple-junction solar cells revealed by time-resolved photoluminescence spectroscopy
Author(s) -
David M. Tex,
Mitsuru Imaizumi,
Yoshihiko Kanemitsu
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.0a1687
Subject(s) - photoluminescence , exponential decay , excitation , materials science , time constant , wavelength , spectroscopy , charge carrier , optoelectronics , atomic physics , molecular physics , optics , analytical chemistry (journal) , physics , chemistry , chromatography , quantum mechanics , nuclear physics , electrical engineering , engineering
We measure the excitation-wavelength and power dependence of time-resolved photoluminescence (PL) from the top InGaP subcell in a InGaP/GaAs/Ge triple-junction solar cell. The wavelength-dependent data reveals that the PL decays are governed by charge separation. A fast single-exponential PL decay is observed at low excitation power densities, which is the charge separation under short-circuit condition. Under strong excitation a bi-exponential PL decay is observed. Its slow component appears at early times, followed by a faster component at late times. The slow decay is the carrier recombination of the subcell. The following fast component is the charge separation process under reduced built-in potential near the operating point. The subcells electrical conversion efficiency close to the operating point is evaluated using this decay time constant.