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Improved efficiency of Cu(In,Ga)Se 2 mini‐module via high‐mobility In 2 O 3 :W,H transparent conducting oxide layer
Author(s) -
Koida Takashi,
Nishinaga Jiro,
Ueno Yuko,
Higuchi Hirofumi,
Takahashi Hideki,
Iioka Masayuki,
Kamikawa Yukiko,
Shibata Hajime,
Niki Shigeru
Publication year - 2019
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.3123
Subject(s) - materials science , crystallite , copper indium gallium selenide solar cells , electron mobility , amorphous solid , equivalent series resistance , layer (electronics) , analytical chemistry (journal) , sheet resistance , substrate (aquarium) , annealing (glass) , optoelectronics , crystallography , nanotechnology , chemistry , metallurgy , electrical engineering , oceanography , engineering , chromatography , voltage , geology
Polycrystalline W and H codoped In 2 O 3 (In 2 O 3 :W,H) transparent conducting oxide (TCO) layers with high electron mobility were found to enhance both the short‐circuit current density ( J sc ) and fill factor (FF) of Cu(In,Ga)Se 2 (CIGS) modules with glass/Mo/CIGS/CdS/ZnO/TCO structures. An In 2 O 3 :W,H TCO layer was formed by reactive plasma deposition without substrate heating, followed by postannealing at 150°C. A phase transition from amorphous to polycrystalline was confirmed during postannealing, and a layer with micrometer‐scale lateral grain sizes evenly covered the rough ZnO surface generated by the naturally textured CIGS. The crystallized In 2 O 3 :W,H film showed high electron mobility (apprixmately 80 cm 2 V −1 s −1 ) at a carrier density of approximately 2 to 3 × 10 20 cm −3 . Therefore, the In 2 O 3 :W,H layer achieved lower sheet resistance and lower free carrier absorption than a ZnO:Al layer, which is commonly used in CIGS modules. The CIGS mini‐module employing the In 2 O 3 :W,H layer with a designated area of 3.792 cm 2 exhibited a higher efficiency ( η ) of 20.93% ( V oc = 3.081 V [translated value per subcell: 0.770 V], short‐circuit current = 33.21 mA [ J sc = 35.03 mA cm −2 ], FF = 0.775) with improved J sc and FF, when compared with a mini‐module employing a ZnO:Al layer. The results indicate that polycrystalline In 2 O 3 ‐based TCOs with high electron mobility are suitable for CIGS solar cells and modules.