Issue 40, 2016

Film morphology evolution during solvent vapor annealing of highly efficient small molecule donor/acceptor blends

Abstract

Solution-processable small molecule photovoltaics based on the novel molecular donor, benzodithiophene terthiophene rhodanine (BTR), recently have shown maximum power conversion efficiencies above 8% for active layer thicknesses up to 400 nm, using post process solvent vapor annealing (SVA) with tetrahydrofuran (THF). Here we report an in situ study on the morphology evolution during SVA using the moderate solvent THF and the good solvent chloroform (CF). The combination of real-time grazing incidence X-ray diffraction (GIXD) and grazing incidence small angle X-ray scattering (GISAXS) allows us to draw a complete picture of the evolution of crystallinity and phase purity during post process annealing. We find that the relative crystallinity compared to the as-cast films is only modestly affected by SVA and solvent choice. However, both the phase purity and the characteristic domain sizes within the film vary significantly and are controlled by the solvent quality as well as exposure time. Using THF, films with high phase purity and desirable characteristic length scales of about 30 nm can be achieved, while the use of CF rapidly leads to excessive film coarsening and less preferable domain sizes on the order of 60 nm, too large for optimized charge separation.

Graphical abstract: Film morphology evolution during solvent vapor annealing of highly efficient small molecule donor/acceptor blends

Supplementary files

Article information

Article type
Paper
Submitted
16 Jun 2016
Accepted
14 Sep 2016
First published
15 Sep 2016

J. Mater. Chem. A, 2016,4, 15511-15521

Film morphology evolution during solvent vapor annealing of highly efficient small molecule donor/acceptor blends

S. Engmann, H. W. Ro, A. Herzing, C. R. Snyder, L. J. Richter, P. B. Geraghty and D. J. Jones, J. Mater. Chem. A, 2016, 4, 15511 DOI: 10.1039/C6TA05056E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements