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Title: Towards the next generation 23% efficient n-type cells with low cost manufacturing

Abstract

Suniva, Inc., in collaboration with the University Center for Excellence in Photovoltaics (UCEP) at the Georgia Institute of Technology (GIT) proposed this comprehensive three year program to enable the development of an advanced high performance product that will help the US regain its competitive edge in PV. This project was designed to overcome cost and efficiency barriers through advances in PV science, technology innovation, low-cost manufacturing and full production of ~22.5% efficient n-type Si cells in Norcross, GA. At the heart of the project is the desire to complement the technology being developed concurrently under the Solarmat and ARPAe initiatives to develop a differentiated product superior in both performance and cost effectiveness to the competing alternatives available on the market, and push towards achieving SunShot objectives while ensuring a sustainable business model based on US manufacturing. A significant reduction of the costs in modules produced today will need to combine reductions in wafer costs, cell processing costs as well as module fabrication costs while delivering a product that is not only more efficient under test conditions but also increases the energy yield in outdoor operations. This project will result in a differentiated high performance product and technology that is consistentmore » with sustaining PV manufacturing in the US for a longer term and further highlights the need for continued support for developing the next generation concepts that can keep US manufacturing thriving to support the growing demand for PV in the US and consistent with the US government’s mandates for energy independence.« less

Authors:
 [1]
  1. Suniva Inc., Norcross, GA (United States)
Publication Date:
Research Org.:
Suniva Inc., Norcross, GA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1352321
Report Number(s):
DOE-Suniva-6815
DOE Contract Number:
ee0006815
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION

Citation Formats

Yelundur, Vijay. Towards the next generation 23% efficient n-type cells with low cost manufacturing. United States: N. p., 2017. Web. doi:10.2172/1352321.
Yelundur, Vijay. Towards the next generation 23% efficient n-type cells with low cost manufacturing. United States. doi:10.2172/1352321.
Yelundur, Vijay. 2017. "Towards the next generation 23% efficient n-type cells with low cost manufacturing". United States. doi:10.2172/1352321. https://www.osti.gov/servlets/purl/1352321.
@article{osti_1352321,
title = {Towards the next generation 23% efficient n-type cells with low cost manufacturing},
author = {Yelundur, Vijay},
abstractNote = {Suniva, Inc., in collaboration with the University Center for Excellence in Photovoltaics (UCEP) at the Georgia Institute of Technology (GIT) proposed this comprehensive three year program to enable the development of an advanced high performance product that will help the US regain its competitive edge in PV. This project was designed to overcome cost and efficiency barriers through advances in PV science, technology innovation, low-cost manufacturing and full production of ~22.5% efficient n-type Si cells in Norcross, GA. At the heart of the project is the desire to complement the technology being developed concurrently under the Solarmat and ARPAe initiatives to develop a differentiated product superior in both performance and cost effectiveness to the competing alternatives available on the market, and push towards achieving SunShot objectives while ensuring a sustainable business model based on US manufacturing. A significant reduction of the costs in modules produced today will need to combine reductions in wafer costs, cell processing costs as well as module fabrication costs while delivering a product that is not only more efficient under test conditions but also increases the energy yield in outdoor operations. This project will result in a differentiated high performance product and technology that is consistent with sustaining PV manufacturing in the US for a longer term and further highlights the need for continued support for developing the next generation concepts that can keep US manufacturing thriving to support the growing demand for PV in the US and consistent with the US government’s mandates for energy independence.},
doi = {10.2172/1352321},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 4
}

Technical Report:

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  • The development of renewable, affordable, and environmentally conscious means of generating energy on a global scale represents a grand challenge of our time. Due to the “permanence” of radiation from the sun, solar energy promises to remain a viable and sustainable power source far into the future. Established single-junction photovoltaic technologies achieve high power conversion efficiencies (pce) near 20% but require complicated manufacturing processes that prohibit the marriage of large-scale throughput (e.g. on the GW scale), profitability, and quality control. Our approach to this problem begins with the synthesis of nanocrystals of semiconductor materials comprising earth abundant elements and characterizedmore » by material and optoelectronic properties ideal for photovoltaic applications, namely Cu2ZnSn(S,Se)4 (CZTSSe). Once synthesized, such nanocrystals are formulated into an ink, coated onto substrates, and processed into completed solar cells in such a way that enables scale-up to high throughput, roll-to-roll manufacturing processes. This project aimed to address the major limitation to CZTSSe solar cell pce’s – the low open-circuit voltage (Voc) reported throughout literature for devices comprised of this material. Throughout the project significant advancements have been made in fundamental understanding of the CZTSSe material and device limitations associated with this material system. Additionally, notable improvements have been made to our nanocrystal based processing technique to alleviate performance limitations due to the identified device limitations. Notably, (1) significant improvements have been made in reducing intra- and inter-nanoparticle heterogeneity, (2) improvements in device performance have been realized with novel cation substitution in Ge-alloyed CZTGeSSe absorbers, (3) systematic analysis of absorber sintering has been conducted to optimize the selenization process for large grain CZTSSe absorbers, (4) novel electrical characterization analysis techniques have been developed to identify significant limitations to traditional electrical characterization of CZTSSe devices, and (5) the developed electrical analysis techniques have been used to identify the role that band gap and electrostatic potential fluctuations have in limiting device performance for this material system. The device modeling and characterization of CZTSSe undertaken with this project have significant implications for the CZTSSe research community, as the identified limitations due to potential fluctuations are expected to be a performance limitation to high-efficiency CZTSSe devices fabricated from all current processing techniques. Additionally, improvements realized through enhanced absorber processing conditions to minimize nanoparticle and large-grain absorber heterogeneity are suggested to be beneficial processing improvements which should be applied to CZTSSe devices fabricated from all processing techniques. Ultimately, our research has indicated that improved performance for CZTSSe will be achieved through novel absorber processing which minimizes defect formation, elemental losses, secondary phase formation, and compositional uniformity in CZTSSe absorbers; we believe this novel absorber processing can be achieved through nanocrystal based processing of CZTSSe which is an active area of research at the conclusion of this award. While significant fundamental understanding of CZTSSe and the performance limitations associated with this material system, as well as notable improvements in the processing of nanocrystal based CZTSSe absorbers, have been achieved under this project, the limitation of two years of research funding towards our goals prevents further significant advancements directly identified through pce. improvements relative to those reported herein. As the characterization and modeling subtask of this project has been the main driving force for understanding device limitations, the conclusions of this analysis have just recently been applied to the processing of nanocrystal based CZTSSe absorbers -- with notable success. We expect the notable fundamental understanding of device limitations and absorber sintering achieved under this project will lead to significant improvements in device performance for CZTSSe devices in the near future for devices fabricated from a variety of processing techniques« less
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  • An additive manufacture technique known as laminated object manufacturing (LOM) was used to fabricate compact ceramic heat exchanger prototypes. LOM uses precision CO2 laser cutting of ceramic green tapes, which are then precision stacked to build a 3D object with fine internal features. Modeling was used to develop prototype designs and predict the thermal response, stress, and efficiency in the ceramic heat exchangers. Build testing and materials analyses were used to provide feedback for the design selection. During this development process, laminated object manufacturing protocols were established. This included laser optimization, strategies for fine feature integrity, lamination fluid control, greenmore » handling, and firing profile. Three full size prototypes were fabricated using two different designs. One prototype was selected for performance testing. During testing, cross talk leakage prevented the application of a high pressure differential, however, the prototype was successful at withstanding the high temperature operating conditions (1300 °F). In addition, analysis showed that the bulk of the part did not have cracks or leakage issues. This led to the development of a module method for next generation LOM heat exchangers. A scale-up cost analysis showed that given a purpose built LOM system, these ceramic heat exchangers would be affordable for the applications.« less