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Title: Positive temperature coefficient of photovoltaic efficiency in solar cells based on InGaN/GaN MQWs

Abstract

We report a 23.4% improvement of conversion efficiency in solar cells based on InGaN/GaN multiple quantum wells by using a patterned sapphire substrate in the fabrication process. The efficiency enhancement is due to the improvement of the crystalline quality, as proven by the reduction of the threading dislocation density. More importantly, the better crystalline quality leads to a positive photovoltaic efficiency temperature coefficient up to 423 K, which shows the property and advantage of wide gap semiconductors like InGaN, signifying the potential of III-nitride based solar cells for high temperature and concentrating solar power applications.

Authors:
; ; ; ; ; ; ; ; ;  [1]; ;  [1];  [2]
  1. State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22594348
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DISLOCATIONS; EFFICIENCY; GALLIUM NITRIDES; INDIUM NITRIDES; PHOTOVOLTAIC EFFECT; QUANTUM WELLS; SAPPHIRE; SEMICONDUCTOR MATERIALS; SOLAR CELLS; SUBSTRATES; TEMPERATURE COEFFICIENT; TEMPERATURE RANGE 0400-1000 K

Citation Formats

Chen, Zhaoying, Zheng, Xiantong, Li, Zhilong, Wang, Ping, Rong, Xin, Wang, Tao, Yang, Xuelin, Xu, Fujun, Qin, Zhixin, Ge, Weikun, Shen, Bo, Wang, Xinqiang, E-mail: wangshi@pku.edu.cn, and Collaborative Innovation Center of Quantum Matter, Beijing 100871. Positive temperature coefficient of photovoltaic efficiency in solar cells based on InGaN/GaN MQWs. United States: N. p., 2016. Web. doi:10.1063/1.4960765.
Chen, Zhaoying, Zheng, Xiantong, Li, Zhilong, Wang, Ping, Rong, Xin, Wang, Tao, Yang, Xuelin, Xu, Fujun, Qin, Zhixin, Ge, Weikun, Shen, Bo, Wang, Xinqiang, E-mail: wangshi@pku.edu.cn, & Collaborative Innovation Center of Quantum Matter, Beijing 100871. Positive temperature coefficient of photovoltaic efficiency in solar cells based on InGaN/GaN MQWs. United States. doi:10.1063/1.4960765.
Chen, Zhaoying, Zheng, Xiantong, Li, Zhilong, Wang, Ping, Rong, Xin, Wang, Tao, Yang, Xuelin, Xu, Fujun, Qin, Zhixin, Ge, Weikun, Shen, Bo, Wang, Xinqiang, E-mail: wangshi@pku.edu.cn, and Collaborative Innovation Center of Quantum Matter, Beijing 100871. Mon . "Positive temperature coefficient of photovoltaic efficiency in solar cells based on InGaN/GaN MQWs". United States. doi:10.1063/1.4960765.
@article{osti_22594348,
title = {Positive temperature coefficient of photovoltaic efficiency in solar cells based on InGaN/GaN MQWs},
author = {Chen, Zhaoying and Zheng, Xiantong and Li, Zhilong and Wang, Ping and Rong, Xin and Wang, Tao and Yang, Xuelin and Xu, Fujun and Qin, Zhixin and Ge, Weikun and Shen, Bo and Wang, Xinqiang, E-mail: wangshi@pku.edu.cn and Collaborative Innovation Center of Quantum Matter, Beijing 100871},
abstractNote = {We report a 23.4% improvement of conversion efficiency in solar cells based on InGaN/GaN multiple quantum wells by using a patterned sapphire substrate in the fabrication process. The efficiency enhancement is due to the improvement of the crystalline quality, as proven by the reduction of the threading dislocation density. More importantly, the better crystalline quality leads to a positive photovoltaic efficiency temperature coefficient up to 423 K, which shows the property and advantage of wide gap semiconductors like InGaN, signifying the potential of III-nitride based solar cells for high temperature and concentrating solar power applications.},
doi = {10.1063/1.4960765},
journal = {Applied Physics Letters},
number = 6,
volume = 109,
place = {United States},
year = {Mon Aug 08 00:00:00 EDT 2016},
month = {Mon Aug 08 00:00:00 EDT 2016}
}
  • High external quantum efficiency (EQE) p-i-n heterojunction solar cellsgrown by NH 3 -based molecular beam epitaxy are presented. EQE values including optical losses are greater than 50% with fill-factors over 72% when illuminated with a 1 sun AM0 spectrum. Optical absorptionmeasurements in conjunction with EQE measurements indicate an internal quantum efficiency greater than 90% for the InGaN absorbing layer. By adjusting the thickness of the top p-type GaN window contact layer, it is shown that the short-wavelength (<365 nm) quantum efficiency is limited by the minority carrier diffusion length in highly Mg-doped p-GaN.
  • High external quantum efficiency (EQE) p-i-n heterojunction solar cells grown by NH{sub 3}-based molecular beam epitaxy are presented. EQE values including optical losses are greater than 50% with fill-factors over 72% when illuminated with a 1 sun AM0 spectrum. Optical absorption measurements in conjunction with EQE measurements indicate an internal quantum efficiency greater than 90% for the InGaN absorbing layer. By adjusting the thickness of the top p-type GaN window contact layer, it is shown that the short-wavelength (<365 nm) quantum efficiency is limited by the minority carrier diffusion length in highly Mg-doped p-GaN.
  • We investigate the photovoltaic performance of pseudomorphic In{sub 0.1}Ga{sub 0.9}N/GaN multiple-quantum well (MQW) solar cells as a function of the total active region thickness. An increase in the number of wells from 5 to 40 improves the short-circuit current and the open-circuit voltage, resulting in a 10-fold enhancement of the overall conversion efficiency. Further increasing the number of wells leads to carrier collection losses due to an incomplete depletion of the active region. Capacitance-voltage measurements point to a hole diffusion length of 48 nm in the MQW region.
  • High internal and external quantum efficiency GaN/InGaN solar cells are demonstrated. The internal quantum efficiency was assessed through the combination of absorption and external quantum efficiency measurements. The measured internal quantum efficiency, as high as 97%, revealed an efficient conversion of absorbed photons into electrons and holes and an efficient transport of these carriers outside the device. Improved light incoupling into the solar cells was achieved by texturing the surface. A peak external quantum efficiency of 72%, a fill factor of 79%, a short-circuit current density of 1.06 mA/cm{sup 2} , and an open circuit voltage of 1.89 V weremore » achieved under 1 sun air-mass 1.5 global spectrumillumination conditions.« less