VII Encontro da SBPMat

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Nanocomposites for Photovolatic Energy Harvesting

Gehan Amaratunga¹*, Daniel Kuo1, Husnu Emrah Unalan¹, Pritesh Hiralal1, Di Wei1,², Yasuhiko Hayashi³

¹Electrical Engineering Division, Engineering Dept., Cambridge University, Cambridge CB3 0FA, UK
² Nokia Research Centre, 11 JJ Thomson Avenue, Cambridge, UK
³ Department of Frontier Materials, Nagoya Institute of Technology, Nagoya, 466-8555, Japan
*Corresponding author & presenter: gaja1@cam.ac.uk

The ability to synthesize nanoscale inorganic semiconductors such as ZnO, FeO, TiO, Si, GaAs and Ge has enabled the exploration of a new class ‘ubiquitous’ photovoltaic (PV) cells on substrates such as fabric and flexible plastic for energy provision. Combination of these nanaosacle materials within a polymer, the nanocomposite, allows for application of PV cells onto surfaces, inaccessible for conventional PV cells, through processes such as painting and printing. The PV surface is in fact an ensemble of nanoscale PV cells which act in an ‘averaged’ manner to give a terminal voltage and current over a defined area. It is important to note that considerations such as power conversion efficiency are secondary. What is important is converting energy from environmental light, usually of much lower intensity than direct sunlight, and possibly storing it locally for ambient use.

Initially the use of a nanocomposite was pursued to enhance the performance of polymer solar cells through easier dissociation of photogenerated excitons. The materials used were C60 [1] and SWCNTs [2]. Currently the best performance is obtained through use of PCBM as the nanomaterial [3]. Here we present results which explore the use of the nanomaterial itself as an additional photoabsorber within the nanocomposite. Energy harvesting cells which combine polymers with ZnO and FeO are discussed. Synthesis of these inorganic semiconductors directly on SWCNTs which act as electrodes is also presented. Enhancement of the photoabsorption process through use of a dye in combination with ZnO nanoparticles allows another degree of freedom in customizing the energy harvesting PV surface.

[1] “Polymer Photovoltaic Cells: Enhanced Efficiency via a network of internal donor-acceptor junctions” G. Yu, J. Gao, J. C. Hummelen, F. Wudl, A. J. Heege, Science, 270, 1759 (1995).

[2] “Single-wall carbon nanotube conjugated polymer photovoltaic devices” E. Kymakis and G. A. J. Amaratunga , App. Phys. Letts.. 80, 112 (2002).

[3] “High-efficiency solution processable polymer photovoltaic cells by self-organization of polymer blends” G Li, V. Shrotriya, J. Huang, Y. Yao, T. Moriarty, K. Emery and Y. Yang, , Nature Mat. 4 864(2005) 864.