Increasing short-circuit current in silicon heterojunction solar cells

Zachary Holman, Antoine Descoeudres, Loris Barraud, Johannes Seif, Fernando Zicarelli, Stefaan De Wolf, Christophe Ballif

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Silicon heterojunction solar cells are emerging photovoltaic devices that have gained particular interest for their very high open-circuit voltages. Unfortunately, the amorphous silicon layers that both passivate the crystalline silicon surfaces and act as emitter and back-surface field introduce new design constraints that often reduce the short-circuit current and fill factor compared to diffused junction solar cells. Here, we investigate the roles of the front and back transparent conductive oxide films, as well as the front amorphous silicon stack, in current generation. Decreasing the doping density of the indium tin oxide (ITO) films at the front of the cells trades optical losses for electrical losses as parasitic, long-wavelength absorption is reduced but film resistance is increased. However, high currents can be obtained while retaining respectable fill factors with proper ITO and metallization combinations. The rear ITO doping may be tuned to promote long wavelength transparency while avoiding fill factor losses due to contact resistance. The p-type amorphous silicon film that forms the emitter is found to be electrically dead in the sense that no light absorbed in this layer contributes to the current. Reducing the layer thickness to improve current generation comes at a price, however, as fill factor also falls. 2×2 cm 2 screen-printed silicon heterojunction solar cells fabricated with these considerations in mind exhibit short-circuit densities above 38 mA/cm 2, open-circuit voltages over 725 mV, and efficiencies as high as 20.8%.

Original languageEnglish (US)
Title of host publicationProgram - 37th IEEE Photovoltaic Specialists Conference, PVSC 2011
Pages1448-1452
Number of pages5
DOIs
StatePublished - Dec 1 2011
Externally publishedYes
Event37th IEEE Photovoltaic Specialists Conference, PVSC 2011 - Seattle, WA, United States
Duration: Jun 19 2011Jun 24 2011

Publication series

NameConference Record of the IEEE Photovoltaic Specialists Conference
ISSN (Print)0160-8371

Other

Other37th IEEE Photovoltaic Specialists Conference, PVSC 2011
CountryUnited States
CitySeattle, WA
Period6/19/116/24/11

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering

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