skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: High-efficiency selective boron emitter formed by wet chemical etch-back for n-type screen-printed Si solar cells

Abstract

Front metal contact induced recombination and resistance are major efficiency limiting factors of large-area screen-printed n-type front junction Si solar cells with homogeneous emitter and tunnel oxide passivated back contact (TOPCON). Here, this paper shows the development of a selective boron emitter (p +/p ++) formed by a screen-printed resist masking and wet chemical etch-back process, which first grows a porous Si layer and subsequently removes it. Various wet-chemical solutions for forming porous Si layer are investigated. An industrial compatible process with sodium nitrite (NaNO 2) catalyst is developed to uniformly etch-back the ~47 Ω/ atmospheric pressure chemical vapor deposited heavily doped boron emitter to ~135 Ω/ by growing a 320 nm porous Si layer within 3 min and subsequently removing it. After etching back, the boron emitter was subjected to a thermal oxidation to lower the surface concentration and the emitter saturation current density J 0e. Various etched-back emitters were evaluated by measuring J 0e on symmetric test structures with atomic layer deposited aluminum oxide (Al 2O 3) passivation. Very low J 0e of 21, 14, and 9 fA/cm 2 were obtained for the 120, 150, and 180 Ω/ etched-back emitters, respectively. A solar cell with a selective emittermore » (65/180 Ω/ ) formed by this etch-back technology and with an Al/Ag contact on the front and TOPCON on the back gave an open-circuit voltage (V oc) of 682.8 mV and efficiency of 21.04% on n-type Czochralski Si wafer. Finally, this demonstrates the potential of this technology for next generation high-efficiency industrial n-type Si solar cells.« less

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [1];  [2]
  1. Georgia Inst. of Technology, Atlanta, GA (United States)
  2. Georgia Inst. of Technology, Atlanta, GA (United States); Suniva Inc., Norcross, GA (United States)
Publication Date:
Research Org.:
Georgia Tech Research Corporation, Atlanta, GA (United States); Suniva, Inc., Norcross, GA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1465957
Alternate Identifier(s):
OSTI ID: 1361726
Grant/Contract Number:  
EE0006336; EE0006815
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 110; Journal Issue: 2; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 14 SOLAR ENERGY

Citation Formats

Tao, Yuguo, Madani, Keeya, Cho, Eunhwan, Rounsaville, Brian, Upadhyaya, Vijaykumar, and Rohatgi, Ajeet. High-efficiency selective boron emitter formed by wet chemical etch-back for n-type screen-printed Si solar cells. United States: N. p., 2017. Web. doi:10.1063/1.4973626.
Tao, Yuguo, Madani, Keeya, Cho, Eunhwan, Rounsaville, Brian, Upadhyaya, Vijaykumar, & Rohatgi, Ajeet. High-efficiency selective boron emitter formed by wet chemical etch-back for n-type screen-printed Si solar cells. United States. doi:10.1063/1.4973626.
Tao, Yuguo, Madani, Keeya, Cho, Eunhwan, Rounsaville, Brian, Upadhyaya, Vijaykumar, and Rohatgi, Ajeet. Mon . "High-efficiency selective boron emitter formed by wet chemical etch-back for n-type screen-printed Si solar cells". United States. doi:10.1063/1.4973626. https://www.osti.gov/servlets/purl/1465957.
@article{osti_1465957,
title = {High-efficiency selective boron emitter formed by wet chemical etch-back for n-type screen-printed Si solar cells},
author = {Tao, Yuguo and Madani, Keeya and Cho, Eunhwan and Rounsaville, Brian and Upadhyaya, Vijaykumar and Rohatgi, Ajeet},
abstractNote = {Front metal contact induced recombination and resistance are major efficiency limiting factors of large-area screen-printed n-type front junction Si solar cells with homogeneous emitter and tunnel oxide passivated back contact (TOPCON). Here, this paper shows the development of a selective boron emitter (p+/p++) formed by a screen-printed resist masking and wet chemical etch-back process, which first grows a porous Si layer and subsequently removes it. Various wet-chemical solutions for forming porous Si layer are investigated. An industrial compatible process with sodium nitrite (NaNO2) catalyst is developed to uniformly etch-back the ~47 Ω/ atmospheric pressure chemical vapor deposited heavily doped boron emitter to ~135 Ω/ by growing a 320 nm porous Si layer within 3 min and subsequently removing it. After etching back, the boron emitter was subjected to a thermal oxidation to lower the surface concentration and the emitter saturation current density J0e. Various etched-back emitters were evaluated by measuring J0e on symmetric test structures with atomic layer deposited aluminum oxide (Al2O3) passivation. Very low J0e of 21, 14, and 9 fA/cm2 were obtained for the 120, 150, and 180 Ω/ etched-back emitters, respectively. A solar cell with a selective emitter (65/180 Ω/ ) formed by this etch-back technology and with an Al/Ag contact on the front and TOPCON on the back gave an open-circuit voltage (Voc) of 682.8 mV and efficiency of 21.04% on n-type Czochralski Si wafer. Finally, this demonstrates the potential of this technology for next generation high-efficiency industrial n-type Si solar cells.},
doi = {10.1063/1.4973626},
journal = {Applied Physics Letters},
number = 2,
volume = 110,
place = {United States},
year = {Mon Jan 09 00:00:00 EST 2017},
month = {Mon Jan 09 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 1 work
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

Silicon nanostructures from electroless electrochemical etching
journal, February 2005