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Amorphous oxides as electron transport layers in Cu(In,Ga)Se 2 superstrate devices
Author(s) -
Heinemann M. D.,
van Hest M. F. A. M.,
Contreras M.,
Perkins J. D.,
Zakutayev A.,
Kaufmann C. A.,
Unold T.,
Ginley D. S.,
Berry J. J.
Publication year - 2017
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.201600870
Subject(s) - copper indium gallium selenide solar cells , materials science , amorphous solid , doping , substrate (aquarium) , layer (electronics) , optoelectronics , gallium , oxide , nanotechnology , chemistry , crystallography , metallurgy , oceanography , geology
Cu(In,Ga)Se2 (CIGS) solar cells in superstrate configuration promise improved light management and higher stability compared to substrate devices, but they have yet to deliver comparable power conversion efficiencies (PCEs). Chemical reactions between the CIGS layer and the front contact were shown in the past to deteriorate the p‐n junction in superstrate devices, which led to lower efficiencies compared to the substrate‐type devices. This work aims to solve this problem by identifying a buffer layer between the CIGS layer and the front contact, acting as the electron transport layer, with an optimized electron affinity, doping density and chemical stability. Using combinatorial material exploration we identified amorphous gallium oxide (a‐GaO x ) as a potentially suitable buffer layer material. The best results were obtained for a‐GaO x with an electron affinity that was found to be comparable to that of CIGS. Based on the results of device simulations, it is assumed that detrimental interfacial acceptor states are present at the interface between CIGS and a‐GaO x . However, these initial experiments indicate the potential of a‐GaO x in this application, and how to reach performance parity with substrate devices, by further increase of its n‐type doping density.