The tunable and amazing properties of plasmonic nanostructures have received significant attentions in the fields of solar energy conversion. Plasmonic nanostructures provide pathways to directly convert solar energy into electric energy by hot-carrier generation. They can also serve as economical electrodes for high-efficient carrier collection. Both have promising potential for manufacturing new generation solar cells. Here, we review recent advances in plasmonic nanostructures for electronic designs of photovoltaic devices and specially focus on plasmonic hot-carrier photovoltaic architectures and plasmonic electrode structures. Technical challenges toward low-cost and high-performance plasmonics-based solar cells are also discussed.
In this paper, Polyurethane-imide (PUI) which has the advantages of polyurethane and polyimide is synthesized and
introduced to apply in the slab optical waveguide devices. The PUI is characterized by infrared spectrum (FT-IR),
differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). Slab optical waveguide is prepared via
spin coating the cyclopentanone solution of PUI on top of K9 glass and cured at 140 °C for 20 minutes to complete
removal of the solvent from the film. The film-formability of PUI is characterized by atomic force microscope (AFM).
The results of DSC and TGA indicate that the PUI exhibits high thermal stability up to its glass-transition temperature
(Tg) of 206 °C and 10% heat loss temperature of 310°C. Optical properties of absorption behavior and propagation loss
are investigated in slab waveguides, and propagation loss of 1.782 dB/cm at 1310nm in TE (transverse electric field)
mode has been achieved by using prism-coupler method. The results show that polyurethane-imide has distinct merits:
good processability, high thermal stability and moderate glass-transition temperature, excellent film-formability, and low
propagation loss. These advantages of polyurethane-imides make them suitable as electro-optic polymeric materials in
Waveguide ring resonators are key elemental devices for wavelength filters, optical switches, lasers and optical sensors.
In order to control the finesse and notch depth of the resonator, the coupling ratio needs to be varied widely and
accurately. A novel thermooptic polymer ring resonator integrated with a tunable directional coupler was theoretical
analyzed. Polymer materials with different thermooptic coefficients were chosen as the core and cladding layers of
waveguides. The structure of the directional coupler was optimized to achieve large tuning range of coupling ratio. The
finesse, notch depth and the resonant frequency peak of the resonator can be controlled precisely by temperature. The
coupled-mode theory (CMD) and beam propagation method (BPM) were used to simulate the characteristics of the
tunable directional coupler. The transmission spectra and loss characteristic of the resonator are also discussed in detail.
This device can be used to improve the performance of integrated optical gyroscope (IOG) and other resonator-based
photonic integrated circuits.