Details
| Original language | English |
|---|---|
| Article number | 7530 |
| Journal | Scientific reports |
| Volume | 10 |
| Publication status | Published - 5 May 2020 |
Abstract
In the search for highly transparent and non-toxic alternative front layers replacing state-of-the-art CdS in Cu(In,Ga)Se2 thin-film solar cells, alternatives rarely exceed reference devices in terms of efficiency. Full-area ultra-thin aluminium oxide tunnelling layers do not require any contact patterning and thus overcome the main drawback of insulating passivation layers. Even a few monolayers of aluminium oxide can be deposited in a controlled manner by atomic layer deposition, they show excellent interface passivation properties, low absorption, and suitable current transport characteristics on test devices. Depositing a ZnO-based transparent front contact, however, results in extremely poor solar cell performance. The issue is not necessarily a low quality of the alternative front layer, but rather the intricate relation between front layer processing and electronic bulk properties in the absorber layer. We identify three challenges critical for the development of novel front passivation approaches: (i) both Cd and Zn impurities beneficially reduce the high native net dopant concentration in the space charge region, (ii) sputter deposition of ZnO damages the passivation layer resulting in increased interface recombination, (iii) thermal treatments of devices with ZnO layer result in substantial Zn diffusion, which can penetrate the full absorber thickness already at moderate temperatures.
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In: Scientific reports, Vol. 10, 7530, 05.05.2020.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Ultra-thin passivation layers in Cu(In,Ga)Se2 thin-film solar cells
T2 - full-area passivated front contacts and their impact on bulk doping
AU - Werner, Florian
AU - Veith-Wolf, Boris
AU - Melchiorre, Michele
AU - Babbe, Finn
AU - Schmidt, Jan
AU - Siebentritt, Susanne
N1 - Funding Information: We thank J. Guillot, N. Valle, and B. El Adib (Luxembourg Institute of Science and Technology, LIST) for XPS and SIMS measurements. This study was funded by the Fonds National de la Recherche Luxembourg (FNR) in the project “Surface passivation for thin film photovoltaics (SURPASS).”
PY - 2020/5/5
Y1 - 2020/5/5
N2 - In the search for highly transparent and non-toxic alternative front layers replacing state-of-the-art CdS in Cu(In,Ga)Se2 thin-film solar cells, alternatives rarely exceed reference devices in terms of efficiency. Full-area ultra-thin aluminium oxide tunnelling layers do not require any contact patterning and thus overcome the main drawback of insulating passivation layers. Even a few monolayers of aluminium oxide can be deposited in a controlled manner by atomic layer deposition, they show excellent interface passivation properties, low absorption, and suitable current transport characteristics on test devices. Depositing a ZnO-based transparent front contact, however, results in extremely poor solar cell performance. The issue is not necessarily a low quality of the alternative front layer, but rather the intricate relation between front layer processing and electronic bulk properties in the absorber layer. We identify three challenges critical for the development of novel front passivation approaches: (i) both Cd and Zn impurities beneficially reduce the high native net dopant concentration in the space charge region, (ii) sputter deposition of ZnO damages the passivation layer resulting in increased interface recombination, (iii) thermal treatments of devices with ZnO layer result in substantial Zn diffusion, which can penetrate the full absorber thickness already at moderate temperatures.
AB - In the search for highly transparent and non-toxic alternative front layers replacing state-of-the-art CdS in Cu(In,Ga)Se2 thin-film solar cells, alternatives rarely exceed reference devices in terms of efficiency. Full-area ultra-thin aluminium oxide tunnelling layers do not require any contact patterning and thus overcome the main drawback of insulating passivation layers. Even a few monolayers of aluminium oxide can be deposited in a controlled manner by atomic layer deposition, they show excellent interface passivation properties, low absorption, and suitable current transport characteristics on test devices. Depositing a ZnO-based transparent front contact, however, results in extremely poor solar cell performance. The issue is not necessarily a low quality of the alternative front layer, but rather the intricate relation between front layer processing and electronic bulk properties in the absorber layer. We identify three challenges critical for the development of novel front passivation approaches: (i) both Cd and Zn impurities beneficially reduce the high native net dopant concentration in the space charge region, (ii) sputter deposition of ZnO damages the passivation layer resulting in increased interface recombination, (iii) thermal treatments of devices with ZnO layer result in substantial Zn diffusion, which can penetrate the full absorber thickness already at moderate temperatures.
UR - http://www.scopus.com/inward/record.url?scp=85084195851&partnerID=8YFLogxK
U2 - 10.1038/s41598-020-64448-9
DO - 10.1038/s41598-020-64448-9
M3 - Article
C2 - 32371994
AN - SCOPUS:85084195851
VL - 10
JO - Scientific reports
JF - Scientific reports
SN - 2045-2322
M1 - 7530
ER -