UNS: Exploring the feasibility of plasmonic nanocrystal solar cells utilizing strongly confined radiation.

Bowling Green State University, Bowling Green OH

Investigators

Abstract

PI Name: Mikhail Zamkov Proposal number: 1510503 The sun represents the most abundant potential source of sustainable energy on earth. Solar cells convert sunlight to electricity through the use of photovoltaic (PV) materials, which are expensive. One method to reduce the cost of making PV materials is to cast suspensions of nano-sized semiconductor crystals called quantum dots into a continuous thin sheet, a process called solution processing. However, thin-film PV materials made by this method have a poor trade off with respect to the thickness needed to provide good solar energy absorption versus good electrical conduction through the film. To address this issue, the goal of this project is to introduce another type of nano-sized metal particle into the solution processing scheme that will improve the power conversion performance of the thin film. This specially designed metal particle, called a plasmonic particle, exploits a quantum mechanical principle called confined radiation to improve the light absorption of the film, leading to potential improvements in the power conversion efficiency. The educational activities associated with the project will involve undergraduates in research through the Building Ohio's Sustainable Energy Future (BOSEF) program. The solution-based fabrication of colloidal semiconductor nanocrystals (quantum dots) into thin-film photovoltaic (PV) devices offers a route for low-cost manufacture. Unfortunately, the electrical conductivity in solution-cast semiconductor PV thin films is poor, requiring exceptionally thin films that cannot fully absorb the incident light. The overall goal of the proposed research is to fabricate and study the performance of photovoltaic cells which rely on the near-field antenna emission of metal nanoparticles to funnel solar energy into the absorber layer. Theoretically, this type of plasmon radiation can enhance the optical density of photovoltaic devices beyond the conventional far-field scattering employed by most plasmonic or photonically-enhanced crystal cells. If successful, this enhanced absorption layer can fully absorb light at film thicknesses needed to maintain low conduction losses, leading to enhanced photovoltaic performance. To enable the photovoltaic conversion of near-field emission into electric power, plasmonic films will be assembled by doping the semiconductor nanocrystal solids with electrically-insulated metal nanoparticles where the far-field emission is suppressed. In this way, the near-field emission will be harvested by coupling the plasmon radiation directly to resonant transitions of semiconductor nanocrystals. Photoconductivity and time-resolved spectroscopy will be used to measure near-field energy conversion into electrical power. The thermal impact of heat-prone metal nanoparticles will be alleviated by using a matrix-encapsulation approach, where colloidal nanocrystals are imbedded into all-inorganic matrices that have tunable interparticle distances. The proposed research will be conducted in collaboration with the Wright Center for Photovoltaics Innovation and Commercialization (PVIC), where students will be trained the industry-grade equipment and build scientific relationships with industry partners.