EES Blog

Nanophotonic concepts, ranging from photonic crystals to nanowire arrays, are of tremendous interest in both solid state and photoelectrochemical (PEC) energy conversion devices.

Rinnerbauer et al, in 2012, presented a review on an emerging direction in photonics, high-temperature nanophotonics using large area 2D metallic photonic crystals aimed at solid-state energy conversion. Recently, Hu et al have shown impressive optical results in GaAs nanowire array photoanodes (for PEC devices) that occupy <5% of the fractional area of the electrode, due to efficient incoupling into the resonant waveguide modes. Despite the differences in their intended application, both papers share a common theme: use of fundamental yet scalable nanophotonic concepts in energy conversion.

Photonic crystals (PhCs) are periodically nanostructured metamaterials with unique optical properties and flexibility in the design of their density of states. In their review, Rinnerbauer et al demonstrate the efficiency of selective emitters based on 2D photonic crystals in refractory metals (like Tantalum and Tungsten). These PhCs are paving the way for high efficiency high temperature thermal-to-electricity conversion schemes based on selective emitters and absorbers, like TPV, solar thermal and solar TPV.

Work by Hu et al shows that enhanced optical absorption, in conjunction with radial carrier-collection, results in high external quantum yields (EQYs) when the periodic nanowire arrays of GaAs are used as energy-conversion devices. The key to the absorption properties of these arrays is guided and leaky optical waveguide modes determined through a combination of experimental and theoretical analysis.

Nanophotonic device design certainly has a big role in the future of energy-conversion. A variety of schemes have been proposed and demonstrated in both solid state and PEC systems and these papers represent critical steps in nanophotonic energy conversion.

By Prineha Narang

Read the papers here:

Recent developments in high-temperature photonic crystals for energy conversion
Veronika Rinnerbauer, Sidy Ndao, Yi Xiang Yeng, Walker R. Chan, Jay J. Senkevich, John D. Joannopoulos, Marin Soljacic and Ivan Celanovic
DOI: 10.1039/c2ee22731b

Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire-array photoanodes
Shu Hu, Chun-Yung Chi, Katherine T. Fountaine, Maoqing Yao, Harry A. Atwater, P. Daniel Dapkus, Nathan S. Lewis and Chongwu Zhou
DOI: 10.1039/c3ee40243f

Interested in photonics research? See our collection of articles on photonics that are free to access for a limited time here.