The emerging field of plasmonics has yielded methods for guiding and localizing light at the nanoscale, well below the scale of the wavelength of light in free space. Now plasmonics researchers are turning their attention to photovoltaics, where design approaches based on plasmonics can be used to improve absorption in photovoltaic devices, permitting a considerable reduction in the physical thickness of solar photovoltaic absorber layers, and yielding new options for solar-cell design. In this review, we survey recent advances at the intersection of plasmonics and photovoltaics and offer an outlook on the future of solar cells based on these principles.

Plasmonics for improved photovoltaic devices

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

The remarkable performance of lead halide perovskites in solar cells can be attributed to the long carrier lifetimes and low non-radiative recombination rates, the same physical properties that are ideal for semiconductor lasers. Here, we show room-temperature and wavelength-tunable lasing from single-crystal lead halide perovskite nanowires with very low lasing thresholds (220 nJ cm(-2)) and high quality factors (Q ∼ 3,600). The lasing threshold corresponds to a charge carrier density as low as 1.5 × 10(16) cm(-3). Kinetic analysis based on time-resolved fluorescence reveals little charge carrier trapping in these single-crystal nanowires and gives estimated lasing quantum yields approaching 100%. Such lasing performance, coupled with the facile solution growth of single-crystal nanowires and the broad stoichiometry-dependent tunability of emission colour, makes lead halide perovskites ideal materials for the development of nanophotonics, in parallel with the rapid development in photovoltaics from the same materials.

Lead halide perovskite nanowire lasers with low lasing thresholds and high quality factors

Optical generation of hot electrons in metallic structures and its potential as an alternative to conventional electron–hole separation in semiconductor devices are reviewed. The possibilities for realizing high conversion efficiencies with low fabrication costs are discussed along with challenges in terms of the materials, architectures and fabrication methods

Plasmon-induced hot-electron generation at nanoparticle/metal-oxide interfaces for photovoltaic and photocatalytic devices

Optical Waveguide Theory

InP nanowire arrays have been grown and optimized using selective area epitaxy by metalorganic chemical vapour deposition technique. High quality stacking fault free wurtzite nanowires with a wide range of diameters and room temperature minority carrier lifetime as high as ∼ 1.6 ns have been obtained. An axially doped n-i-p structure was further grown and successfully fabricated into solar cell devices. The photovoltaic behaviors of the device have been investigated and compared to simulation results.

Selective area epitaxial growth of InP nanowire array for solar cell applications

By combining Finite-Difference-Time-Domain simulations and the detailed-balance model of solar cell, we study how absorption efficiency determines the short circuit current density, J sc , of single vertical nanowire (NW) solar cells. We find that due to the very high absorption efficiency, vertical NW delivers J sc that are one order of magnitude higher than planar solar cells.

Extremely high short-circuit current density in vertical single nanowire solar cells

Selective area epitaxy for integration of In(Ga)As/GaAs quantum dot based optoelectronic devices and comparison with intermixing techniques

Nanoplasmonics for Light Trapping in Solar Cells

Electron beam-induced current (EBIC) technique combined with simulations were used to study the axial p-n junctions of InP nanowire array solar cells. Photovoltaic devices have also been fabricated and characterized to confirm the EBIC results.

Sudha Mokkapati

Papers

Selective area epitaxial growth of InP nanowire array for solar cell applications

Extremely high short-circuit current density in vertical single nanowire solar cells

Selective area epitaxy for integration of In(Ga)As/GaAs quantum dot based optoelectronic devices and comparison with intermixing techniques

Nanoplasmonics for Light Trapping in Solar Cells

Direct Characterization of Axial p-n Junctions for InP Nanowire Array Solar Cells Using Electron Beam-Induced Current