Imaging of nanoscale charge transport in bulk heterojunction solar cells

Published

June 17, 2011

Author(s)

Behrang H. Hamadani, Nadine E. Gergel-Hackett, Paul M. Haney, Nikolai B. Zhitenev

Abstract

We have studied the local charge transport properties of organic bulk heterojunction solar cells based on the blends of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) with a photoconductive atomic force microscope (PCAFM). We explore the role of morphology on transport of photogenerated electrons or holes by careful consideration of the sample geometry and the choice of the atomic force microscope (AFM) tip. We then consider the role of the film/tip contact on the local current-voltage characteristics of these structures and present a model based on a drift and diffusion description of transport. We find that our simple 1D model can only reproduce qualitative features of the data using unphysical parameters, indicating that more sophisticated modeling is required to capture all the nonideal characteristics of the AFM transport measurements. Our results show that the PCAFM contrast can be directly related to the material nanomorphology only under a narrow and well-defined range of the measurement conditions.

Citation

Journal of Applied Physics

Volume

109

Issue

12

Pub Type

Journals

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Keywords

photoconductive AFM, organic photovoltaics, scanning probe microscopy, photocurrent

Citation

Hamadani, B. , Gergel-Hackett, N. , Haney, P. and Zhitenev, N. (2011), Imaging of nanoscale charge transport in bulk heterojunction solar cells, Journal of Applied Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=905890 (Accessed October 4, 2025)