Time-dependent efficiency measurements of polymer solar cells with dye additives: unexpected initial increase of efficiency

Kyle J Bandaccari,Parisa Tajalli-Tehrani Valverde,Mitchel Bugaj,Richard P Barber,Brian J Mcnelis,Grace E Chesmore

doi:10.1051/epjpv/2018003

Kyle J Bandaccari, Parisa Tajalli-Tehrani Valverde + Show 4 more

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https://doi.org/10.1051/epjpv/2018003

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Journal: EPJ Photovoltaics	Publication Date: Jan 1, 2018
License type: CC BY 4.0

Affiliation: Santa Clara University

Abstract

We report the effects of the addition of two azo-dye additives on the time-dependent efficiency of polymer solar cells. Although the maximum efficiencies of devices containing different amounts of dye do not vary greatly over the selected concentration range, the time dependence results reveal a surprising initial increase in efficiency in some samples. We observe this effect to be correlated with a leakage current, although a specific mechanism is not yet identified. We also present the measured lifetimes of these solar cells, and find that variations in dye concentrations produce a small effect at most. Characterization of the bulk heterojunction layer (active layer) morphology using atomic-force microscope (AFM) imaging reveals reordering patterns which suggest that the primary effects of the dyes arise via structural, not absorptive, characteristics.

Highlights

Third-generation, solution-processed solar cells represent the forefront of research in solar technology
Since the first observation of a photoactive polymer engaging in an electron transfer process [1], polymer solar cells (PSCs) have garnered substantial attention in the subfield of organic photovoltaics [2]
The h values corresponding to successive IV curves decay exponentially and monotonically as shown in the inset

Summary

Introduction

Third-generation, solution-processed solar cells represent the forefront of research in solar technology. Since the first observation of a photoactive polymer engaging in an electron transfer process [1], polymer solar cells (PSCs) have garnered substantial attention in the subfield of organic photovoltaics [2]. Conventional inorganic solar cells base their photoactive layers upon crystalline semiconductor-grade silicon, a material which requires the use of harsh and hazardous etchants such as hydrofluoric acid and handling within a strict cleanroom environment to prevent contamination during processing. The active layers of PSCs may be applied in solution [4]. PSCs, may be produced much more safely, quickly, and than their silicon-based counterparts in methods which require fewer specialized apparatuses

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