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Title: In-situ X-ray Nanocharacterization of Defect Kinetics in Chalcogenide Solar Cell Materials

Abstract

For decades the optimization of polycrystalline absorbers has been done using an Edisonian approach, where trial and error and complex design of experiments in large parameter spaces have driven efficiencies to the record values we see today – CIGS at 22.5%, 22.1% for CdTe, 21.3% for high purity multi-crystalline silicon. Appropriate growth parameters are critical to ensure good quality crystals with low concentration of structural defects - low dislocation density and large grain sizes. However, to bridge the gap between the efficiencies today and the fundamental Shockley-Queisser limit for these materials a much more fundamental understanding of the role and interaction between composition, structure, defect density and electrical properties is required. In recent years multiple novel characterization techniques have shown the potential that nanoscale characterization can have in deciphering the composition of grain boundaries in materials like CIGS and CdTe. However, high resolution has come at the cost of small sampling areas and number of specimens, making it extremely difficult to draw conclusions based on the characteristic small sampling sizes. The missing links thus far have been: (1) the lack of statistical meaningfulness of the nanosclae studies and (2) the direct correlation of compositional variations to electrical performance with nanoscalemore » resolution. In this work we present the use of synchrotron-based nano-X-ray fluorescence microscopy (nano-XRF), x-ray absorption nanospectroscopy (nano-XAS) coupled with nano-x-ray beam induced current (nano-XBIC) as ideal tools for investigating elemental, chemical and electrical properties of large areas of solar cell materials at the sub-micron scale with very high sensitivity. We show how the technique can provide statistical valuable information regarding the elemental segregation in CIGS and the direct correlation to current collection. For example, we demonstrate that Cu and Ga (and with that, CGI and GGI) correlate positively, and In negatively with charge collection efficiency for cells with low Ga content, both at grain boundaries and in grain cores. For cells with high Ga content, the charge collection efficiency depends to much lesser extent on the elemental distribution. The objective is three folded: (1) develop an x-ray in-situ microscopy capability to simulate growth and processing conditions, (2) apply it to elucidate performance-governing defect kinetics in chalcogenide solar cell materials, and (3) to study approaches to engineer materials from the nanoscale up. The development of these capabilities will enable experimental characterization to take place under actual processing and operating conditions and it will have impact well beyond the proposed research, enabling future studies on a large variety of materials system where electronic properties depend on underlying structural or chemical inhomogeneities.« less

Authors:
ORCiD logo [1];  [2];  [2];  [3]
  1. Arizona State Univ., Tempe, AZ (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
Research Org.:
Arizona State Univ., Tempe, AZ (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1398242
Report Number(s):
DOE-ASU-05948
DOE Contract Number:
EE0005948
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 14 SOLAR ENERGY; X-ray microscopy; CIGS characterization; CIGS defects

Citation Formats

Bertoni, Mariana, Lai, Barry, Masser, Jorg, and Buonassisi, Tonio. In-situ X-ray Nanocharacterization of Defect Kinetics in Chalcogenide Solar Cell Materials. United States: N. p., 2016. Web. doi:10.2172/1398242.
Bertoni, Mariana, Lai, Barry, Masser, Jorg, & Buonassisi, Tonio. In-situ X-ray Nanocharacterization of Defect Kinetics in Chalcogenide Solar Cell Materials. United States. doi:10.2172/1398242.
Bertoni, Mariana, Lai, Barry, Masser, Jorg, and Buonassisi, Tonio. Wed . "In-situ X-ray Nanocharacterization of Defect Kinetics in Chalcogenide Solar Cell Materials". United States. doi:10.2172/1398242. https://www.osti.gov/servlets/purl/1398242.
@article{osti_1398242,
title = {In-situ X-ray Nanocharacterization of Defect Kinetics in Chalcogenide Solar Cell Materials},
author = {Bertoni, Mariana and Lai, Barry and Masser, Jorg and Buonassisi, Tonio},
abstractNote = {For decades the optimization of polycrystalline absorbers has been done using an Edisonian approach, where trial and error and complex design of experiments in large parameter spaces have driven efficiencies to the record values we see today – CIGS at 22.5%, 22.1% for CdTe, 21.3% for high purity multi-crystalline silicon. Appropriate growth parameters are critical to ensure good quality crystals with low concentration of structural defects - low dislocation density and large grain sizes. However, to bridge the gap between the efficiencies today and the fundamental Shockley-Queisser limit for these materials a much more fundamental understanding of the role and interaction between composition, structure, defect density and electrical properties is required. In recent years multiple novel characterization techniques have shown the potential that nanoscale characterization can have in deciphering the composition of grain boundaries in materials like CIGS and CdTe. However, high resolution has come at the cost of small sampling areas and number of specimens, making it extremely difficult to draw conclusions based on the characteristic small sampling sizes. The missing links thus far have been: (1) the lack of statistical meaningfulness of the nanosclae studies and (2) the direct correlation of compositional variations to electrical performance with nanoscale resolution. In this work we present the use of synchrotron-based nano-X-ray fluorescence microscopy (nano-XRF), x-ray absorption nanospectroscopy (nano-XAS) coupled with nano-x-ray beam induced current (nano-XBIC) as ideal tools for investigating elemental, chemical and electrical properties of large areas of solar cell materials at the sub-micron scale with very high sensitivity. We show how the technique can provide statistical valuable information regarding the elemental segregation in CIGS and the direct correlation to current collection. For example, we demonstrate that Cu and Ga (and with that, CGI and GGI) correlate positively, and In negatively with charge collection efficiency for cells with low Ga content, both at grain boundaries and in grain cores. For cells with high Ga content, the charge collection efficiency depends to much lesser extent on the elemental distribution. The objective is three folded: (1) develop an x-ray in-situ microscopy capability to simulate growth and processing conditions, (2) apply it to elucidate performance-governing defect kinetics in chalcogenide solar cell materials, and (3) to study approaches to engineer materials from the nanoscale up. The development of these capabilities will enable experimental characterization to take place under actual processing and operating conditions and it will have impact well beyond the proposed research, enabling future studies on a large variety of materials system where electronic properties depend on underlying structural or chemical inhomogeneities.},
doi = {10.2172/1398242},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Sep 21 00:00:00 EDT 2016},
month = {Wed Sep 21 00:00:00 EDT 2016}
}

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