DocumentCode :
1858753
Title :
Single to multi-scale texturing for high efficiency micromorph thin film silicon solar cell
Author :
Boccard, Mathieu ; Cuony, Peter ; Battaglia, Corsin ; Hänni, Simon ; Nicolay, Sylvain ; Ding, Laura ; Benkhaira, Mustapha ; Bonnet-Eymard, Maximilien ; Bugnon, Gregory ; Charrière, Mathieu ; Söderström, Karin ; Escarre-palou, Jordi ; Despeisse, Matthieu ;
Author_Institution :
IMT - PVLAB (EPFL), Neuchatel, Switzerland
fYear :
2011
fDate :
19-24 June 2011
Abstract :
Summary form only given. Improving micromorph devices performances nowadays requires a current density increase: good devices typically exhibit an open circuit voltage times fill factor product of one (Voc×FF~1.4V×0.71=1). Their short-circuit current density (Jsc) value thus dictates their efficiency (expressed in %). Maximizing it with reasonable cells thicknesses necessitates therefore combining robust cell design with adequate light management through transparent electrodes and intermediate reflectors engineering. We will first show how record micromorph devices (13.5% initial and >;11.5% stabilized efficiencies) are prepared on optimized single-layer ZnO electrodes. Such electrodes requirements will be discussed: 1) Strong and wide light scattering is needed on the entire useful wavelength range. Large features grant high total currents (>;26mA/cm2) while sharp ones allow for high top cell currents (>;13mA/cm2). 2) Sufficiently small or smooth substrate features permits high quality cell growth, providing good cell design (typically Voc over 1.4V). 3) Good conduction and transparency for electrodes (requiring ~50cm2/V/s TCO mobility) should preserve sheet resistance close to 20Ω/□ (for FF>;70%) with low absorption. We will then focus on pushing further micromorph devices potential. Either textured intermediate reflectors can fulfill the bottom cell needs, or double-texture substrates can be implemented: light scattering at large wavelengths is here achieved via nanoimprint lithography (a versatile approach to glass-texturing), topped by small and sharp ZnO features guaranteeing high top cell current. By combining excellent TCO with smart under-structures, thin devices delivering high currents with excellent efficiencies are within reach.
Keywords :
II-VI semiconductors; current density; electrochemical electrodes; elemental semiconductors; silicon; solar cells; thin film devices; wide band gap semiconductors; zinc compounds; Si; ZnO; double-texture substrates; fill factor product; high efficiency micromorph thin film silicon solar; intermediate reflector engineering; light management; micromorph devices; multiscale texturing; nanoimprint lithography; open circuit voltage; optimized single-layer electrodes; short-circuit current density; textured intermediate reflectors; transparent electrodes; wide light scattering; Current density; Electrodes; IEEE Xplore; Light scattering; Robustness; Substrates; Zinc oxide;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Photovoltaic Specialists Conference (PVSC), 2011 37th IEEE
Conference_Location :
Seattle, WA
ISSN :
0160-8371
Print_ISBN :
978-1-4244-9966-3
Type :
conf
DOI :
10.1109/PVSC.2011.6186072
Filename :
6186072
Link To Document :
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