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Microscopic insight into the impact of the KF post‐deposition treatment on optoelectronic properties of (Ag,Cu)(In,Ga)Se 2 solar cells
Author(s) -
Krause Maximilian,
Márquez José A.,
Levcenco Sergej,
Unold Thomas,
DonzelGargand Olivier,
Edoff Marika,
AbouRas Daniel
Publication year - 2022
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.3466
Subject(s) - solar cell , deposition (geology) , materials science , layer (electronics) , scanning electron microscope , optoelectronics , open circuit voltage , recombination , alloy , analytical chemistry (journal) , current density , chemistry , nanotechnology , voltage , metallurgy , composite material , physics , paleontology , biochemistry , chromatography , quantum mechanics , sediment , gene , biology
It is attractive to alloy Cu(In,Ga)Se 2 solar‐cell absorbers with Ag (ACIGSe), since they lead to similar device performances as the Ag‐free absorber layers, while they can be synthesized at much lower deposition temperatures. However, a KF post‐deposition treatment (PDT) of the ACIGSe absorber surface is necessary to achieve higher open‐circuit voltages ( V oc ). The present work provides microscopic insights to the effects of this KF PDT, employing correlative scanning‐electron microscope techniques on identical positions of cross‐sectional specimens of the cell stacks. We found that the increase in V oc after the KF PDT can be explained by the removal of Cu‐poor, Ag‐poor, and Ga‐rich regions near the ACIGSe/CdS interface. The KF PDT leads, when optimally doped, to a very thin K‐Ag‐Cu‐Ga‐In‐Se layer between ACIGSe and CdS. If the KF dose is too large, we find that Cu‐poor and K‐rich regions form near the ACIGSe/CdS interface with enhanced nonradiative recombination which explains a decrease in the V oc . This effect occurs in addition to the presence of a (K,Ag,Cu)InSe 2 intermediate layer, that might be responsible for limiting the short‐current density of the solar cells due to a current blocking behavior.