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Title: Surface and bulk effects of K in Cu 1-xK xIn 1-yGa ySe 2 solar cells

Abstract

Two strategies for enhancing photovoltaic (PV) performance in chalcopyrite solar cells were investigated: Cu 1-xK xIn 1-yGa ySe 2 absorbers with low K content (K/(K+Cu), or x ~ 0.07) distributed throughout the bulk, and CuIn 1-yGa ySe 2 absorbers with KIn 1-yGa ySe 2 grown on their surfaces. Distributing K throughout the bulk absorbers improved power conversion efficiency, open-circuit voltage (VOC) and fill factor (FF) for Ga/(Ga+In) of 0, 0.3 and 0.5. Surface KIn 1-yGa ySe 2 and bulk x ~ 0.07 Cu 1-xK xIn 1-yGa ySe 2 films with Ga/(Ga+In), or y of 0.3 and 0.5 also had improved efficiency, VOC, and FF, relative to CuIn 1-yGa ySe 2 baselines. On the other hand, y ~ 1 absorbers did not benefit from K introduction. Similar to Cu 1-xK xInSe 2, the formation of Cu 1-xK xGaSe 2 alloys was favored at low temperatures and high Na supply by the substrate, relative to the formation of mixed-phase CuGaSe 2 + KGaSe 2. KIn 1-yGa ySe 2 alloys were grown for the first time, as evidenced by X-ray diffraction and ultraviolet/visible spectroscopy. For all Ga/(Ga+In) compositions, the surface KIn 1-yGa ySe 2 absorbers had superior PV performance in buffered and buffer-freemore » devices. However, the bulk x ~ 0.07 absorbers only outperformed the baselines in buffered devices. The data demonstrate that KIn 1-yGa ySe 2 passivates the surface of CuIn 1-yGa ySe 2 to increase efficiency, VOC, and FF, while bulk Cu 1-xK xIn 1-yGa ySe 2 absorbers with x ~ 0.07 enhance efficiency, VOC, and FF by some other mechanism.« less

Authors:
 [1];  [2]
  1. Univ. of Florida, Gainesville, FL (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Univ. of Florida, Gainesville, FL (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1417137
Report Number(s):
NREL/JA-5K00-70736
Journal ID: ISSN 0927-0248
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Solar Energy Materials and Solar Cells
Additional Journal Information:
Journal Volume: 179; Journal Issue: C; Journal ID: ISSN 0927-0248
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; Cu(In,Ga)Se2; chalcopyrite; potassium; passivation; (Cu,K)GaSe2; K(In,Ga)Se2

Citation Formats

Muzzillo, Christopher P., and Anderson, Timothy J.. Surface and bulk effects of K in Cu1-xKxIn1-yGaySe2 solar cells. United States: N. p., 2017. Web. doi:10.1016/j.solmat.2017.12.038.
Muzzillo, Christopher P., & Anderson, Timothy J.. Surface and bulk effects of K in Cu1-xKxIn1-yGaySe2 solar cells. United States. doi:10.1016/j.solmat.2017.12.038.
Muzzillo, Christopher P., and Anderson, Timothy J.. Fri . "Surface and bulk effects of K in Cu1-xKxIn1-yGaySe2 solar cells". United States. doi:10.1016/j.solmat.2017.12.038.
@article{osti_1417137,
title = {Surface and bulk effects of K in Cu1-xKxIn1-yGaySe2 solar cells},
author = {Muzzillo, Christopher P. and Anderson, Timothy J.},
abstractNote = {Two strategies for enhancing photovoltaic (PV) performance in chalcopyrite solar cells were investigated: Cu1-xKxIn1-yGaySe2 absorbers with low K content (K/(K+Cu), or x ~ 0.07) distributed throughout the bulk, and CuIn1-yGaySe2 absorbers with KIn1-yGaySe2 grown on their surfaces. Distributing K throughout the bulk absorbers improved power conversion efficiency, open-circuit voltage (VOC) and fill factor (FF) for Ga/(Ga+In) of 0, 0.3 and 0.5. Surface KIn1-yGaySe2 and bulk x ~ 0.07 Cu1-xKxIn1-yGaySe2 films with Ga/(Ga+In), or y of 0.3 and 0.5 also had improved efficiency, VOC, and FF, relative to CuIn1-yGaySe2 baselines. On the other hand, y ~ 1 absorbers did not benefit from K introduction. Similar to Cu1-xKxInSe2, the formation of Cu1-xKxGaSe2 alloys was favored at low temperatures and high Na supply by the substrate, relative to the formation of mixed-phase CuGaSe2 + KGaSe2. KIn1-yGaySe2 alloys were grown for the first time, as evidenced by X-ray diffraction and ultraviolet/visible spectroscopy. For all Ga/(Ga+In) compositions, the surface KIn1-yGaySe2 absorbers had superior PV performance in buffered and buffer-free devices. However, the bulk x ~ 0.07 absorbers only outperformed the baselines in buffered devices. The data demonstrate that KIn1-yGaySe2 passivates the surface of CuIn1-yGaySe2 to increase efficiency, VOC, and FF, while bulk Cu1-xKxIn1-yGaySe2 absorbers with x ~ 0.07 enhance efficiency, VOC, and FF by some other mechanism.},
doi = {10.1016/j.solmat.2017.12.038},
journal = {Solar Energy Materials and Solar Cells},
number = C,
volume = 179,
place = {United States},
year = {Fri Dec 29 00:00:00 EST 2017},
month = {Fri Dec 29 00:00:00 EST 2017}
}

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