نرگس عجم گرد

In this work, the optical absorption enhancement of the organic (P3HT:PCBM) solar cells in the presence of silver nanopyramids was investigated with a finite-difference time-domain method. The nanopyramids’ base lengths were changed from 40 to 160 nm. The results show for nanopyramids with a base length of 100 nm, the surface plasmon polariton as well as the effective forward scattering modes are excited effectively, which significantly contribute in enhancement of optical and electrical properties of organic solar cells. Due to the better light concentration in the absorption layer by nanopyramids, which are located under the ITO layer, this design is showed to be more influential in increasing the optical and electrical properties of the cells. The results show that for nanopyramids with a base length of 100 nm, the highest short-circuit current density enhancement are achieved.

In this article, plasmonic waveguides aimed to controlling the colloidal quantum dot spontaneous emission rate have been designed. To this end, with considering aluminum and silver waveguides, the dependence of plasmonic emission rate to the dimension, material, and the place of quantum dots have been investigated. The results show that for a quantum dot with a distance of 5 nm from the edge of a silver waveguide with a gap of 20 nm and width of 30 nm, the plasmonic emission rate enhancement reaches 209 at the wavelength of 480 nm. This value for aluminum is 30. This waveguide is appropriate for ZnCdS/ZnS colloidal quantum dot with a photoluminescence peak at cyan wavelength.

In this work, plasmonic bowtie nano-antennas (as two opposite nano-prisms) for enhancing the electric field and Purcell’s factor of InGaN/GaN quantum dot emitters have been designed. To this end, at first, gold, silver, copper, and aluminum bowties have been investigated. The primary results showed aluminum bowties are more suitable for low wavelength excitations near the green band. Then, the size, gap, and substrate of aluminum bowties have been examined. The results showed aluminum nano-antennas with the length of 63.6 nm, the thickness of 30 nm, top angle of 300, and gap of 20 nm, when are grown on GaN/glass as substrate, results in a Purcell;s factor of 81 with a resonance wavelength of 535 nm. Replacing the AlN/glass with GaN/glass substrate, results in a Purcell’s factor of 86.3 and resonance wavelength of 495 nm.