TECHNOLOGY AREAS: Ground/Sea Vehicles, Materials/Processes

ACQUISITION PROGRAM: Marine Corps Science and Technology, Office of Naval Research

OBJECTIVE: Research the technologies to produce high conversion efficiency, stretchable photovoltaic modules for lightweight power generation.

DESCRIPTION: High efficiency thin film photovoltaics that can be applied to any shaped surface as a stretchable "skin" offer the potential for new mobile power generating capacity. Commercially available photovoltaics that incorporate thin semiconductor films on plastic or thin metal substrates are sufficiently flexible and lightweight to be rolled up for easy transport. Unrolled, the photovoltaic systems are planar and not highly deformable. Achieving stretchable photovoltaics that allow conformable application will require that the complete system of active and passive components be designed to accommodate a fully elastic mechanical response to deformation. Optimization of conversion efficiencies should consider a range of second- and third-generation materials, enhanced broad spectrum absorption concepts, and associated interconnect, integration, and packaging strategies. The goal of this research is to achieve lightweight stretchable (conformable) photovoltaic arrays with conversion efficiencies of >12% and specific power and reliability that compare favorably with existing flexible photovoltaic technologies.

PHASE I: Evaluate photovoltaic materials, device design, and processing technology options to achieve conversion efficiencies of >12% with elastic response to biaxial strains up to 30%. Define specifications and testing protocols for Phase II experimental prototype.

PHASE II: Apply the designs developed in Phase I to fabricate a scalable working prototype photovoltaic modules and conduct appropriate tests to demonstrate photovoltaic (electrical) and mechanical performance in a laboratory environment. Conduct detailed experimental and theoretical analysis of system performance and trade-offs. Assess process scalability and cost-effectiveness.

PHASE III: Develop a stretchable photovoltaic module for integration into expeditionary force equipment or platform. Conduct field testing to demonstrate performance and reliability.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Dual use applications would develop through scaled-up manufacture of cost-effective high efficiency, stretchable photovoltaic "skins" for portable and/or non-obtrusive conformable power generation applications, including flexible battery-charging covers for electric scooters and hybrid/all-electric vehicles, battery-charging sun-umbrellas.

REFERENCES:
1. http://www.powerfilmsolar.com
2. http://www.uni-solar.com
3. Kim, D.-H.; Ahn, J.-H.; et al., "Stretchable and Foldable Si Integrated Circuits," Science 2008, vol. 320, pp. 507-511.
4. Sun, Y.; Choi, W. M.; et al., "Controlled Buckling of Semiconductor Nanoribbons for Stretchable Eletronics," Nature Nanotechnology 2006, vol. 1, 201-207.

KEYWORDS: Photovoltaics, power generation, conformable