EAGER: Plasmonic Wide Angle Light Concentrators for Bulk-Heterojunction Solar Cells

University Of Washington, Seattle WA

Investigators

Abstract

PI: Yu, Qiuming Proposal Number: 1346859 Institution: University of Washington Title: EAGER: Plasmonic Wide Angle Light Concentrators for Bulk-Heterojunction Solar Cells Organic bulk heterojunction (BHJ) solar cells offer the potential advantages as low-cost, lightweight, flexible, and large area devices that can be fabricated in the roll-to-roll printing method. Despite the recent progress in the increase of power conversion efficiency (PCE) of organic BHJ solar cells, fundamental breakthrough has to be made in order to develop high efficiency solar cells especially those working for wide light incident angles. This EAGER project will explore the concept of integrating novel plasmonic wide angle light concentrators as transparent electrodes in BHJ solar cells to tune and enhance transmitted light to match the energy band gaps of the donor and acceptor in the active layer in a wide range of incident angles. Electromagnetic finite-difference time-domain (FDTD) simulations will be applied to rationally design the plasmonic nanostructures and the transfer matrix (TM) optical modeling will be used to design the entire device architecture to ensure the maximum light absorption in the active layer. The designed plasmonic nanostructures will be made on glass substrates via the nanoimprinting method which can be extended to the low-cost roll-to-roll printing method. The effects of far-field light transmission and near-field electric field enhancement induced by plasmonic nanostructures on the performance of BHJ solar cells and the fundamental physical processes in solar energy conversion will be elucidated by conducting the experimental measurements on photocurrent density-voltage curve, reflectance and UV-Vis absorption spectroscopy, steady state and dynamic photoluminescence (PL), and external quantum efficiency (EQE). The objective of this work is to fundamentally understand the physical principles and processes governing the tuning of wide angle light absorption and the enhancement of charge transport and collection in BHJ solar cells by plasmonic nanostructures via a combined electromagnetic simulation and experimental approach. By integrating plasmonic wide angle light concentrators as transparent electrodes in BHJ solar cells, it will allow one to (1) replace the expensive ITO; (2) tune and concentrate far-field transmitted light to match the band gaps of donor and acceptor in the active layer; (3) enable wide angle absorption without mechanical moving parts; and (4) understand near-filed electric field enhancement on exciton generation and charge separation, transport and collection. A wide angle light concentrator enabled by plasmonic nanostructures will be developed and integrated into organic BHJ solar cells to enhance the solar energy conversion efficiency even at large oblique incident angles. The fundamental investigation and experimental findings from this work can be generalized for guiding the development of other types of solar cells and novel optoelectronic and plasmonic devices. Graduate and undergraduate students from underrepresented groups such as female will receive training and participate in this highly interdisciplinary research project.