Performance potential of low-defect density silicon thin-film solar cells obtained by electron beam evaporation and laser crystallisation

¹ Suntech R&D Australia, Pty., Ltd. 82-86 Bay St., Botany, NSW 2019, Australia
² University of NSW Sydney, NSW 2052, Australia

^a e-mail: s.varlamov@unsw.edu.au

Received: 30 July 2012
Published online: 11 January 2013

Abstract

A few microns thick silicon films on glass coated with a dielectric intermediate layer can be crystallised by a single pass of a line-focused diode laser beam. Under favorable process conditions relatively large linear grains with low defect density are formed. Most grain boundaries are defect-free low-energy twin-boundaries. Boron-doped laser crystallised films are processed into solar cells by diffusing an emitter from a phosphorous spin-on-dopant source, measuring up to 539 mV open-circuit voltage prior to metallisation. After applying a point-contact metallisation the best cell achieves 7.8% energy conversion efficiency, open-circuit voltage of 526 mV and short-circuit current of 26 mA/cm². The efficiency is significantly limited by a low fill-factor of 56% due to the simplified metallisation approach. The internal quantum efficiency of laser crystallised cells is consistent with low front surface recombination. By improving cell metallisation and enhancing light-trapping the efficiencies of above 13% can be achieved.