No Cover Image

Journal article 297 views

Interfacial Chemical Composition and Molecular Order in Organic Photovoltaic Blend Thin Films Probed by Surface-Enhanced Raman Spectroscopy / Joseph Razzell-Hollis; Quentin Thiburce; Wing C. Tsoi; Ji-Seon Kim

ACS Applied Materials & Interfaces, Volume: 8, Issue: 45, Pages: 31469 - 31481

Swansea University Author: Tsoi, Chung

Full text not available from this repository: check for access using links below.

Check full text

DOI (Published version): 10.1021/acsami.6b12124

Abstract

Organic electronic devices invariably involve transfer of charge carriers between the organic layer and at least one metal electrode, and they are sensitive to the local properties of the organic film at those interfaces. Here, we demonstrate a new approach for using an advanced technique called sur...

Full description

Published in: ACS Applied Materials & Interfaces
ISSN: 1944-8244 1944-8252
Published: 2016
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa32047
Tags: Add Tag
No Tags, Be the first to tag this record!
Abstract: Organic electronic devices invariably involve transfer of charge carriers between the organic layer and at least one metal electrode, and they are sensitive to the local properties of the organic film at those interfaces. Here, we demonstrate a new approach for using an advanced technique called surface-enhanced raman spectroscopy (SERS) to quantitatively probe interfacial properties relevant to charge injection/extraction. Exploiting the evanescent electric field generated by a ∼7 nm thick layer of evaporated silver, Raman scattering from nearby molecules is enhanced by factors of 10–1000× and limited by a distance dependence with a measured decay length of only 7.6 nm. When applied to the study of an all-polymer 1:1 blend of P3HT and F8TBT used in organic solar cells, we find that the as-cast film is morphologically suited to charge extraction in inverted devices, with a top (anode) interface very rich in hole-transporting P3HT (74.5%) and a bottom (cathode) interface slightly rich in electron-transporting F8TBT (55%). While conventional, uninverted P3HT:F8TBT devices are reported to perform poorly compared to inverted devices, their efficiency can be improved by thermal annealing but only after evaporation of a metallic top electrode. This is explained by changes in composition at the top interface: annealing prior to silver evaporation leads to a greater P3HT concentration at the top interface to 83.3%, exaggerating the original distribution that favored inverted devices, while postevaporation annealing increases the concentration of F8TBT at the top interface to 34.8%, aiding the extraction of electrons in a conventional device. By nondestructively probing buried interfaces, SERS is a powerful tool for understanding the performance of organic electronic devices.
Keywords: charge extraction; conjugated polymers; interfacial properties; organic electronics; SERS
College: College of Engineering
Issue: 45
Start Page: 31469
End Page: 31481