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Title: Determining interface properties limiting open-circuit voltage in heterojunction solar cells

Abstract

The development of new thin-film photovoltaic (PV) absorbers is often hindered by the search for an optimal heterojunction contact; an unoptimized contact may be mistaken for poor quality of the underlying absorber, making it difficult to assess the reasons for poor performance. Therefore, quantifying the loss in device efficiency and open-circuit voltage (VOC) as a result of the interface is a critical step in evaluating a new material. In the present work, we fabricate thin-film PV devices using cuprous oxide (Cu2O), with several different n-type heterojunction contacts. Their current-voltage characteristics are measured over a range of temperatures and illumination intensities (JVTi). We quantify the loss in VOC due to the interface and determine the effective energy gap at the interface. The effective interface gap measured by JVTi matches the gap measured by X-ray photoelectron spectroscopy, albeit with higher energy resolution and an order of magnitude faster. We discuss potential artifacts in JVTi measurements and areas where analytical models are insufficient. Applying JVTi to complete devices, rather than incomplete material stacks, suggests that it can be a quick, accurate method to assess the loss due to unoptimized interface band offsets in thin-film PV devices.

Authors:
 [1]; ORCiD logo [1];  [2];  [1];  [1]
  1. Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
  2. National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S), SunShot Initiative
OSTI Identifier:
1364054
Report Number(s):
NREL/JA-5J00-68693
Journal ID: ISSN 0021-8979; JAPIAU
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 121; Journal Issue: 18
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; activation energies; solar cells; heterojunctions; band gap; illumination

Citation Formats

Brandt, Riley E., Mangan, Niall M., Li, Jian V., Lee, Yun Seog, and Buonassisi, Tonio. Determining interface properties limiting open-circuit voltage in heterojunction solar cells. United States: N. p., 2017. Web. doi:10.1063/1.4982752.
Brandt, Riley E., Mangan, Niall M., Li, Jian V., Lee, Yun Seog, & Buonassisi, Tonio. Determining interface properties limiting open-circuit voltage in heterojunction solar cells. United States. doi:10.1063/1.4982752.
Brandt, Riley E., Mangan, Niall M., Li, Jian V., Lee, Yun Seog, and Buonassisi, Tonio. Tue . "Determining interface properties limiting open-circuit voltage in heterojunction solar cells". United States. doi:10.1063/1.4982752.
@article{osti_1364054,
title = {Determining interface properties limiting open-circuit voltage in heterojunction solar cells},
author = {Brandt, Riley E. and Mangan, Niall M. and Li, Jian V. and Lee, Yun Seog and Buonassisi, Tonio},
abstractNote = {The development of new thin-film photovoltaic (PV) absorbers is often hindered by the search for an optimal heterojunction contact; an unoptimized contact may be mistaken for poor quality of the underlying absorber, making it difficult to assess the reasons for poor performance. Therefore, quantifying the loss in device efficiency and open-circuit voltage (VOC) as a result of the interface is a critical step in evaluating a new material. In the present work, we fabricate thin-film PV devices using cuprous oxide (Cu2O), with several different n-type heterojunction contacts. Their current-voltage characteristics are measured over a range of temperatures and illumination intensities (JVTi). We quantify the loss in VOC due to the interface and determine the effective energy gap at the interface. The effective interface gap measured by JVTi matches the gap measured by X-ray photoelectron spectroscopy, albeit with higher energy resolution and an order of magnitude faster. We discuss potential artifacts in JVTi measurements and areas where analytical models are insufficient. Applying JVTi to complete devices, rather than incomplete material stacks, suggests that it can be a quick, accurate method to assess the loss due to unoptimized interface band offsets in thin-film PV devices.},
doi = {10.1063/1.4982752},
journal = {Journal of Applied Physics},
number = 18,
volume = 121,
place = {United States},
year = {Tue May 09 00:00:00 EDT 2017},
month = {Tue May 09 00:00:00 EDT 2017}
}