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Doped hydrogenated nanocrystalline silicon oxide layers for high‐efficiency c‐Si heterojunction solar cells
Author(s) -
Zhao Yifeng,
Mazzarella Luana,
Procel Paul,
Han Can,
Yang Guangtao,
Weeber Arthur,
Zeman Miro,
Isabella Olindo
Publication year - 2020
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.3256
Subject(s) - materials science , passivation , amorphous silicon , nanocrystalline silicon , chemical vapor deposition , crystalline silicon , optoelectronics , silicon , nanocrystalline material , heterojunction , layer (electronics) , doping , amorphous solid , conductivity , nanotechnology , crystallography , chemistry
Hydrogenated nanocrystalline silicon oxide (nc‐SiO x :H) layers exhibit promising optoelectrical properties for carrier‐selective‐contacts in silicon heterojunction (SHJ) solar cells. However, achieving high conductivity while preserving crystalline silicon (c‐Si) passivation quality is technologically challenging for growing thin layers (less than 20 nm) on the intrinsic hydrogenated amorphous silicon ((i)a‐Si:H) layer. Here, we present an evaluation of different strategies to improve optoelectrical parameters of SHJ contact stacks founded on highly transparent nc‐SiO x :H layers. Using plasma‐enhanced chemical vapor deposition, we firstly investigate the evolution of optoelectrical parameters by varying the main deposition conditions to achieve layers with refractive index below 2.2 and dark conductivity above 1.00 S/cm. Afterwards, we assess the electrical properties with the application of different surface treatments before and after doped layer deposition. Noticeably, we drastically improve the dark conductivity from 0.79 to 2.03 S/cm and 0.02 to 0.07 S/cm for n‐ and p‐contact, respectively. We observe that interface treatments after (i)a‐Si:H deposition not only induce prompt nucleation of nanocrystals but also improve c‐Si passivation quality. Accordingly, we demonstrate fill factor improvement of 13.5% abs from 65.6% to 79.1% in front/back‐contacted solar cells. We achieve conversion efficiency of 21.8% and 22.0% for front and rear junction configurations, respectively. The optical effectiveness of contact stacks based on nc‐SiO x :H is demonstrated by averagely 1.5 mA/cm 2 higher short‐circuit current density thus nearly 1% abs higher cell efficiency as compared with the (n)a‐Si:H.