Fabrication of Ag Nanoparticles Embedded in Al: ZnO as Potential Light-Trapping Plasmonic Interface for Thin Film Solar Cells Hisham Nasser & Zaki M. Saleh & Engin Özkol & Mete Günoven & Alpan Bek & Raşit Turan Received: 25 January 2013 / Accepted: 11 April 2013 / Published online: 26 April 2013 # Springer Science+Business Media New York 2013 Abstract Incident photon conversion efficiency of the ab- sorbing materials at either side of a thin film solar module can be enhanced by integrating a plasmonic interface. Silver nanoparticles represent a good candidate that can be inte- grated to a thin film solar cell for efficient light-trapping. The aim of this work is to fabricate plasmonically active interface consisting of Ag nanoparticles embedded in Al:ZnO that has the potential to be used at the front surface and at the back reflector of a thin film solar cell to enhance light-trapping and increase the photoconversion efficiency. We show that Ag can readily dewet the Al:ZnO surface when annealed at temperatures significantly lower than the melting temperature of Ag, which is beneficial for lowering the thermal budget and cost in solar cell fabrication. We find that such an interface fabricated by a simple dewetting technique leads to plasmonic resonance in the visible and near infrared regions of the solar spectrum, which is impor- tant in enhancing the conversion efficiency of thin film solar cells. Keywords Silver nanoparticles . Dewetting . Plasmonic resonance . Light-trapping . Solar cells . Aluminum zincoxide Introduction Thin film solar cells have gone through a long history of development to improve the conversion efficiency and make it a more competitive source of renewable energy. Optimizing the properties of the basic components has reached a fairly mature level, although drawbacks remain. [1, 2] While further development in the basic components is still needed, there is a clear need to harvest more of the solar spectrum available to the cell. In fact, in a solar cell with a typical bandgap of ∼ 1.8 eV, over 50 % of the solar radiation is transmitted unutilized by the cell. [3] Consequently, a great deal of today’ s research is focused on light management schemes to optimize light- trapping and maximize absorption in the active layer. These schemes target almost total utilization of above-bandgap pho- tons and more of the sub-bandgap ones. To maximize absorp- tion, schemes involving cells with different bandgaps in tandem and nanostructured materials with variable bandgap have been implemented. [4–6] Efficient utilization of hot carriers through the so-called multiple exciton generation has also been reported. [7, 8] Antireflection coating to minimize reflective losses, [9] highly reflective back contacts, [10] texturing of surfaces and interfaces, [11] and using layers with matching refractive index to preferentially scatter light into the active layer [12] have all been used to optimize light absorption in the active layer. However, many of these schemes involve high H. Nasser : Z. M. Saleh (*) : E. Özkol : M. Günoven : A. Bek : R. Turan Center for Solar Energy Research and Applications (GÜNAM), Middle East Technical University, 06800, Ankara, Turkey e-mail: zsaleh@aauj.edu A. Bek : R. Turan Department of Physics, Middle East Technical University, 06800, Ankara, Turkey Z. M. Saleh On leave of absence at GÜNAM from the Arab American University-Jenin, Jenin, Palestine H. Nasser : M. Günoven Micro and Nanotechnology Program of Graduate School of Natural and Applied Sciences, Middle East Technical University, 06800, Ankara, Turkey E. Özkol Department of Chemical Engineering, Middle East Technical University, 06800, Ankara, Turkey Plasmonics (2013) 8:1485–1492 DOI 10.1007/s11468-013-9562-6