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The Application of Sputtered Gallium Oxide as Buffer for Cu(In,Ga)Se 2 Solar Cells
Author(s) -
Witte Wolfram,
Paetel Stefan,
Menner Richard,
Bauer Andreas,
Hariskos Dimitrios
Publication year - 2021
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.202100180
Subject(s) - copper indium gallium selenide solar cells , materials science , gallium , open circuit voltage , band gap , optoelectronics , amorphous solid , sputtering , energy conversion efficiency , sputter deposition , solar cell , substrate (aquarium) , thin film , analytical chemistry (journal) , nanotechnology , voltage , chemistry , metallurgy , crystallography , electrical engineering , oceanography , geology , engineering , chromatography
Crystalline gallium oxide is a promising wide‐bandgap semiconductor material, especially for applications in high‐frequency and high‐power devices. With an optical bandgap energy well above 4 eV, which implies no visible light absorption, it is also a candidate for one of the front‐side layers in thin‐film solar cells. X‐ray amorphous gallium oxide (a‐Ga 2 O 3 ) deposited by RF magnetron sputtering is applied as an n‐type buffer layer in substrate‐type configuration solar cells based on industry‐relevant inline coevaporated Cu(In,Ga)Se 2 (CIGS) absorbers, which include an i‐ZnO/ZnO:Al bilayer as the front electrode. The cells exhibit an efficiency peak at Ga 2 O 3 deposition temperatures in the range of 140–180 °C and show mostly a gain in short‐circuit current density compared with the CdS‐buffered reference cells, as a result of the high optical bandgap of a‐Ga 2 O 3 in the range of 4.6–4.8 eV. The CIGS solar cells with sputtered a‐Ga 2 O 3 buffers reach efficiencies of almost 14%, lacking in open‐circuit voltage and fill factor, whereas the CdS‐buffered cells are on a 16–17% level. Light soaking of the cells leads to a slight improvement of the fill factor, but the gap in open‐circuit voltage of 80–100 mV in contrast to the CdS‐buffered reference cells remains unaffected.