Thin, Flexible, Quantum-Structured Solar Cells

ABSTRACT: The epitaxial liftoff of multi-junction structures provides a means to build photovoltaic devices that are flexible, light weight, and highly efficient. However, current approaches to increasing the AM0 efficiency of multi-junction structures are reaching practical limitations due to the complexity of the device design. The objective of this Phase II SBIR program is to develop innovative designs based upon third generation photovoltaic device concepts. By combining wide and narrow band gap material within each p-n junction, quantum-structured solar cells can increase the current and the voltage output of each of the subcells within a multi-junction solar cell. Ultimately our approach provides a pathway for obtaining, thin, flexible, single-junction solar cells with AM0 efficiency approaching 40%. BENEFIT: Photovoltaic (PV) devices can provide a mobile source of electrical power for a variety of military applications in both space and terrestrial environments. Many of these mobile power applications can directly benefit from enhancements in the efficiency of the photovoltaic devices. In particular, flexible, lightweight, high-efficiency solar cells are needed to maximize the power generating capability of space platforms. Ground-based and air-based defense applications can also benefit from the development of flexible, lightweight cells with improved efficiency. The technology developed during this program is expected to have immediate market opportunities for defense applications. The SBIR project described here is also part of a larger effort to realize the ultimate objective of third generation photovoltaics, namely ultra-high conversion efficiency at low costs for terrestrial photovoltaic power. Ultra-high efficiency solar cells could substantially enhance the overall performance of terrestrial concentrator photovoltaic systems. This technology could thus accelerate the adoption of photovoltaics into the renewable energy market to address the world"s growing energy needs without degrading the environment. In addition to its potential commercial value and social benefits, this SBIR program will enhance the technical understanding of quantum-structured devices.