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TY  - THES
AU  - Qiu, Depeng
TI  - Development of industry-scalable processes for nanocrystalline silicon oxide in silicon heterojunction solar cells
VL  - 619
PB  - RWTH Aachen University
VL  - Dissertation
CY  - Jülich
M1  - RWTH-2023-10814
T2  - Schriften des Forschungszentrums Jülich. Reihe Energie & Umwelt = Energy & environment
SP  - 1 Online-Ressource (202 Seiten) : Illustrationen, Diagramme
PY  - 2023
N1  - Druckausgabe: 2023. - Onlineausgabe: 2023. - Auch veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2024
N1  - Dissertation, RWTH Aachen University, 2023
AB  - Thanks to the excellent passivation of hydrogenated amorphous silicon (a-Si:H) to wafer surface, high open circuit voltage (Voc) as well as power conversion efficiency (η) have been achieved by the silicon heterojunction (SHJ) solar cell technology in the recent decades. However, a significant parasitic absorption in doped a-Si:H re- sults in a low short circuit current density (Jsc), limiting the cell performance of SHJ solar cells. Doped hydrogenated nanocrystalline silicon oxide (nc-SiOx:H), consisting of conductive silicon crystallites (nc-Si:H) embedded in transparent hydrogenated amorphous silicon oxide (a-SiOx:H) matrix, is an attractive alternative material to the commonly used a-Si:H in SHJ solar cells to further improve the cell performance. A trade-off between the optical and the electrical properties always need to be taken into account when applying the nc-SiOx:H(n) films in SHJ solar cells. The goal of this thesis is to systematically investigate the implementation of nc-SiOx:H(n) in SHJ solar cells, to find the correlation between the material properties and the de- vice performance, and to demonstrate the industrial applicability of nc-SiOx:H in SHJ solar cells.In the first part of this work, n-type nc-SiOx:H and hydrogenated nanocrys- talline silicon (nc-Si:H) (x equals zero) layers were developed and compared in an industrial multi-substrate plasma enhanced chemical vapor deposition (PECVD) system for the application in full-sized (>156×156 mm2) SHJ solar cells. By means of optical, electrical and structural material characterizations, the influence of de- position parameters, such as deposition power density (P ), deposition pressure (p) and gas compositions, was investigated. It was found that the response of nc-SiOx:H to the variation of deposition parameters is different from that of nc-Si:H layers. Moreover, a synergistic effect of CO2 and PH3 or SiH4 on the material properties of nc-SiOx:H films was observed. To acquire the nc-SiOx:H films with high transparency and sufficient conductivity, high volume fraction of a-SiOx:H (Fa-SiO2 ) and nc-Si:H (Fc), but low a-Si:H volume fraction (Fa-Si:H) are required. Furthermore, a very good homogeneity of the nc-SiOx:H(n) films prepared in this large-area system was demonstrated.In the second part of this work, the nc-SiOx:H layers at thickness of 15 nm were integrated in the rear-junction SHJ solar cells as electron transport layer (ETL) on n-type quarter-M2-sized c-Si wafers. It was demonstrated that the variation of material properties of nc-SiOx:H(n) does not affect the Voc but has a big influence on the Jsc and the fill factor (FF ) of SHJ solar cells as well as the contact resistivity (ρc) of indium tin oxide (ITO) / nc-SiOx:H(n). It was found that the ρc of ITO / nc-SiOx:H(n) can be reduced by increasing the dark conductivity (σ) and the Fc, or reducing the optical band gap (E04) of nc-SiOx:H(n). In total, the best performed cell in the preliminary development shows Voc of 728 mV, FF of 76.7
LB  - PUB:(DE-HGF)11 ; PUB:(DE-HGF)3
DO  - DOI:10.18154/RWTH-2023-10814
UR  - https://publications.rwth-aachen.de/record/973466
ER  -