Thin, Flexible, Quantum-Structured Solar Cells

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 I SBIR program is to develop and validate innovative designs based upon third generation photovoltaic device concepts. By combining wide and narrow band gap material in one 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. The short-term focus of this SBIR project will be on using quantum structures to enhance the performance of InGaP-based solar cells typically used as the top subcell in multi-junction structures. Ultimately our approach promises to provide a pathway for obtaining, thin, flexible, single-junction solar cells with AM0 efficiency approaching 40%. BENEFIT: Light weight and highly efficient solar cells are needed to maximize the power generating capability of space platforms. Ground-based defense applications can also require photovoltaic power arrays capable of operating over a wide range of temperature and solar spectrum conditions. Conventional multijunction solar cells can provide high conversion efficiencies, but only under limited environmental conditions. The objective of this SBIR program is to develop a flexible yet ultra-high efficient solar cell that can approach 40% efficiency over a wide range of operating conditions. 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. The wider operating conditions enabled by single-junction quantum 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 well devices.