Premium
High‐forward‐bias transport mechanism in a‐Si:H/c‐Si heterojunction solar cells
Author(s) -
Schulze T. F.,
Korte L.,
Conrad E.,
Schmidt M.,
Rech B.
Publication year - 2010
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.200982747
Subject(s) - heterojunction , biasing , x ray photoelectron spectroscopy , diode , materials science , open circuit voltage , solar cell , dark current , optoelectronics , analytical chemistry (journal) , silicon , voltage , chemistry , physics , photodetector , nuclear magnetic resonance , quantum mechanics , chromatography
In order to elucidate the transport mechanism in a‐Si:H/c‐Si heterojunction solar cells under high forward bias ( U > 0.5 V), we conducted temperature‐dependent measurements of current–voltage ( I – V ) curves in the dark and under illumination. ZnO:Al/(p)a‐Si:H/( n )c‐Si/(n + )a‐Si:H cells are compared with inversely doped structures and the impact of thin undoped a‐Si:H buffer layers on charge carrier transport is explored. The solar cell I – V curves are analyzed employing a generalized two‐diode model which allows fitting I – V data for a broad range of samples. The fitting results are complemented with numerical simulations using AFORS‐HET under consideration of microscopic a‐Si:H parameters as determined by constant‐final‐state‐yield photoelectron spectroscopy (CFSYS) to identify possible origins for a systematic increase of the high‐forward‐bias ideality factor along with the open‐circuit voltage ( V oc ). It is further shown that also for a‐Si:H/c‐Si heterojunctions, dark I – V curve fit parameters can unequivocally be linked to V oc under illumination, which may prove helpful for device assessment.