Solution Combustion Synthesis of Transparent & Conducting Thin Films With
Substituted or Reduced Use of Indium for Photovoltaic Applications
Sana Ullah
1
*
, Rita Branquinho, Tiago Mateus, Rodrigo Martins, Elvira Fortunato
*
CENIMAT/I3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e
Tecnologia (FCT), Universidade Nova de Lisboa (UNL), and CEMOP/UNINOVA,
Caparica, Portugal
1
Deparment of Basic Sciences, Khawaja Fareed Universiy of Engineering & Information
Technology (KFUE & IT), Rahim Yar Khan, Pakistan
;
Transparent and conducting IZO and GZO thin films were prepared by mixing indium, zinc
and gallium precursor solutions in different metal ratios. Film stacks with 10 layers were
obtained by sequential spin-coating each layer at 3000 rpm for 30 seconds and pre-annealing
at 400°C for 10 minutes after deposition. A single step post-deposition rapid thermal
annealing (RTA) in vacuum, O2 and N2-5%H2 atmospheres was provided at 600°C for 10
minutes to all films. RTA has been observed to be very effective in enhancing career
concentrations and their mobility in comparatively very short time of application. The lowest
resistivity obtained was 4.3 x 10
-3
Ω-cm for indium-rich IZO, 8.8 x 10
-3
Ω-cm for zinc-rich
IZO, and 1.3 x 10
-2
Ω-cm for GZO films after RTA in vacuum. Si-based photovoltaic solar
cell devices were produced with these TCOs and compared to standard TCO photovoltaic
devices. Solution processed TCO films show improved total transmittance over standard
TCO. In comparison to efficiency of 6.88% for standard cell, an efficiency of 1.66%, 2.17%,
and 0.77% was obtained for In-rich IZO, Zn-rich IZO and GZO TCO based solution
processed devices respectively. Increase of oxide source materials concentration in precursor
solutions can further reduce resistivity and enhance solar-cell efficiency.
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