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Title: Berkeley Lab Sheds Light on Improving Solar Cell Efficiency

Abstract

Typical manufacturing methods produce solar cells with an efficiency of 12-15%; and 14% efficiency is the bare minimum for achieving a profit. In work performed at the Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley, CA, 5 10-486-577 1)--a US Department of Energy national laboratory that conducts unclassified scientific research and is managed by the University of California--scientist Scott McHugo has obtained keen insights into the impaired performance of solar cells manufactured from polycrystalline silicon. The solar cell market is potentially vast, according to Berkeley Lab. Lightweight solar panels are highly beneficial for providing electrical power to remote locations in developing nations, since there is no need to build transmission lines or truck-in generator fuel. Moreover, industrial nations confronted with diminishing resources have active programs aimed at producing improved, less expensive solar cells. 'In a solar cell, there is a junction between p-type silicon and an n-type layer, such as diffused-in phosphorous', explained McHugo, who is now with Berkeley Lab's Accelerator and Fusion Research Division. 'When sunlight is absorbed, it frees electrons, which start migrating in a random-walk fashion toward that junction. If the electrons make it to the junction; they contribute to the cell's output of electric current. Often, however,more » before they reach the junction, they recombine at specific sites in the crystal' (and, therefore, cannot contribute to current output). McHugo scrutinized a map of a silicon wafer in which sites of high recombination appeared as dark regions. Previously, researchers had shown that such phenomena occurred not primarily at grain boundaries in the polycrystalline material, as might be expected, but more often at dislocations in the crystal. However, the dislocations themselves were not the problem. Using a unique heat treatment technique, McHugo performed electrical measurements to investigate the material at the dislocations. He was purportedly the first to show that they were 'decorated' with iron.« less

Authors:
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director, Office of Science
OSTI Identifier:
923425
Report Number(s):
LBNL-63228
TRN: US0801827
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Manufacturing Automation
Additional Journal Information:
Journal Volume: 0; Journal Issue: 0; Related Information: Journal Publication Date: 12/01/1997
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 24 POWER TRANSMISSION AND DISTRIBUTION; 43 PARTICLE ACCELERATORS; ACCELERATORS; DISLOCATIONS; EFFICIENCY; ELECTRIC CURRENTS; ELECTRONS; GRAIN BOUNDARIES; HEAT TREATMENTS; IRON; MANUFACTURING; MARKET; PERFORMANCE; POWER TRANSMISSION LINES; RECOMBINATION; SILICON; SOLAR CELLS

Citation Formats

Lawrence Berkeley National Laboratory. Berkeley Lab Sheds Light on Improving Solar Cell Efficiency. United States: N. p., 2007. Web.
Lawrence Berkeley National Laboratory. Berkeley Lab Sheds Light on Improving Solar Cell Efficiency. United States.
Lawrence Berkeley National Laboratory. Fri . "Berkeley Lab Sheds Light on Improving Solar Cell Efficiency". United States. https://www.osti.gov/servlets/purl/923425.
@article{osti_923425,
title = {Berkeley Lab Sheds Light on Improving Solar Cell Efficiency},
author = {Lawrence Berkeley National Laboratory},
abstractNote = {Typical manufacturing methods produce solar cells with an efficiency of 12-15%; and 14% efficiency is the bare minimum for achieving a profit. In work performed at the Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley, CA, 5 10-486-577 1)--a US Department of Energy national laboratory that conducts unclassified scientific research and is managed by the University of California--scientist Scott McHugo has obtained keen insights into the impaired performance of solar cells manufactured from polycrystalline silicon. The solar cell market is potentially vast, according to Berkeley Lab. Lightweight solar panels are highly beneficial for providing electrical power to remote locations in developing nations, since there is no need to build transmission lines or truck-in generator fuel. Moreover, industrial nations confronted with diminishing resources have active programs aimed at producing improved, less expensive solar cells. 'In a solar cell, there is a junction between p-type silicon and an n-type layer, such as diffused-in phosphorous', explained McHugo, who is now with Berkeley Lab's Accelerator and Fusion Research Division. 'When sunlight is absorbed, it frees electrons, which start migrating in a random-walk fashion toward that junction. If the electrons make it to the junction; they contribute to the cell's output of electric current. Often, however, before they reach the junction, they recombine at specific sites in the crystal' (and, therefore, cannot contribute to current output). McHugo scrutinized a map of a silicon wafer in which sites of high recombination appeared as dark regions. Previously, researchers had shown that such phenomena occurred not primarily at grain boundaries in the polycrystalline material, as might be expected, but more often at dislocations in the crystal. However, the dislocations themselves were not the problem. Using a unique heat treatment technique, McHugo performed electrical measurements to investigate the material at the dislocations. He was purportedly the first to show that they were 'decorated' with iron.},
doi = {},
journal = {Manufacturing Automation},
number = 0,
volume = 0,
place = {United States},
year = {2007},
month = {7}
}