Delivered by Publishing Technology to: Sung Kyun Kwan University IP: 115.145.159.145 On: Tue, 08 Oct 2013 05:07:17 Copyright: American Scientific Publishers RESEARCH ARTICLE Copyright © 2013 American Scientific Publishers All rights reserved Printed in the United States of America Journal of Nanoscience and Nanotechnology Vol. 13, 7860–7864, 2013 Enhancing Light Trapping Properties of Thin Film Solar Cells by Plasmonic Effect of Silver Nanoparticles Junhee Jung 1† , Kyungyeon Ha 3† , Jaehyun Cho 2 , Shihyun Ahn 2 , Hyeongsik Park 2 , Shahzada Qamar Hussain 1 , Mansoo Choi 3 , and Junsin Yi 1 2 ∗ 1 Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea 2 School of Electronic Electrical Engineering, College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746, Korea 3 Global Frontier Center for Multiscale Energy Systems, Division of WCU Multiscale Mechanical Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-744, Korea The preparation of thin film silicon solar cells containing Ag nanoparticles is reported in this arti- cle. Ag nanoparticles were deposited on fluorine doped tin oxide coated glass substrates by the evaporation and condensation method. a-Si:H solar cells were deposited on these substrates by cluster type plasma enhanced chemical vapor deposition. We discuss the double textured surface effect with respect to both the surface morphology of the substrate and the plasmonic effect of the Ag nanoparticles. Ag nanoparticles of various sizes from 10 to 100 nm were deposited. The haze values of the Ag embedded samples increased with increasing particle size whereas the optical transmittance decreased at the same conditions. The solar cell with the 30 nm size Ag nanopar- ticles showed a short circuit current density of 12.97 mA/cm 2 , which is 0.53 mA/cm 2 higher than that of the reference solar cell without Ag nanoparticles, and the highest quantum efficiency for wavelengths from 550 to 800 nm. When 30 nm size nanoparticles were employed, the conversion efficiency of the solar cell was increased from 6.195% to 6.696%. This study reports the applica- tion of the scattering effect of Ag nanoparticles for the improvement of the conversion efficiency of amorphous silicon solar cells. Keywords: Silver Nanoparticles, Amorphous Silicon Solar Cell, Light Trapping, Plasmonic Effect. 1. INTRODUCTION Thin film silicon solar cells composed of hydrogenated amorphous silicon (a-Si:H) require significantly less mate- rial with a total device thickness ranging from 0.5 to 5 m compared to crystalline silicon (c-Si) wafers, which are at least 300 m thick. The thin absorbing layer can decrease the manufacturing cost of photovoltaic devices. On the other hand, because of the short optical path length of the thin absorbing layer and lower absorption of longer wavelengths, effective light trapping is necessary to enhance the conversion efficiency of a-Si:H thin film solar cells. In order to improve light trapping properties of the thin absorbing layer, most studies about a-Si:H solar cells have focused on various surface modification techniques, such as the use of nanoplate structures 1 to increase the optical ∗ Author to whom correspondence should be addressed. † This two authors contributed equally to this work. path length. However, different substrate morphologies led to variations in film growth, which led to uncertain films properties. 2 The electrical properties of a-Si :H solar cells also deteriorated when the root mean square (RMS) sur- face roughness increased. 22 Recently, the use of a plasmonic nanostructure has emerged as a suitable technique to improve the absorp- tion of light in thin film solar cells. Excitation of local- ized surface plasmons by an electric field results in light scattering under strong surface plasmon absorption bands and enhanced local electromagnetic fields. 3 Suitably local- ized silver nanoparticles enhance the light absorbance of silicon solar cells. 4 Tu et al. 5 investigated the surface plas- monic effect of the Ag films on the flat and patterned glass substrates of a-Si:H thin film solar cells to demonstrate that the efficiency of a cell with a patterned substrate can be improved by light trapping and surface plasmons. Furthermore, Tan et al. 6 reported that a back reflector with plasmonic Ag nanoparticles can provide better light- trapping performance comparable to random textures in 7860 J. Nanosci. Nanotechnol. 2013, Vol. 13, No. 12 1533-4880/2013/13/7860/005 doi:10.1166/jnn.2013.8130