Film thickness dependence of nanoscale arrangement of a chiral electron donor in its blends with an achiral electron acceptor

DOI: 10.1039/D4NR04269G

Authors: Giulia Pancotti (Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)) , C. Elizabeth Killalea (University of Nottingham) , Thomas W. Rees (University of Nottingham) , Letizia Liiro-Peluso (University of Nottingham) , Sergi Riera-Galindo (Institut de Ciència de Materials de Barcelona (ICMAB-CSIC)) , Peter Beton (University of Nottingham) , Mariano Campoy-Quiles (Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) , David B. Amabilino (Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) , Giuliano Siligardi (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nanoscale

State: Published (Approved)
Published: December 2024
Diamond Proposal Number(s): 30198

Abstract: The nanoscale chiral arrangement in a bicomponent organic material system comprising donor and acceptor small molecules is shown to depend on the thickness of a film that is responsive to chiral light in an optoelectronic device. In this bulk heterojunction, a previously unreported chiral bis(diketopyrrolopyrrole) derivative was combined with an achiral non-fullerene acceptor. The optical activity of the chiral compound is dramatically different in the pure material and the composite, showing how the electron acceptor influences the donor’s arrangement compared with the pure molecule. Mueller matrix polarimetric imaging shows the authenticity of this effect and the homogeneity of short range chiral orientations between the molecules, as well as more heterogeneous short and longer range arrangements in the films observed in linear dichroic and birefringent effects. The two-dimensional circular dichroism (CD) maps and spectra show the uniformity of the short range supramolecular interactions both in spun-cast films on quartz and blade-coated films on photovoltaic device substrates, where evidence for the chiral arrangement is uniquely provided by the synchrotron CD measurements. The external quantum efficiency of the devices depends upon the handedness of the light used to excite them and the film thickness, that influences the supramolecular arrangement and organization in the film, and determines the selectivity for left or right circularly polarised light. The difference in external quantum efficiency of the photovoltaic devices between the two handedness’ of light correlates with the apparent differential absorbance (g-factor) of the films.

Diamond Keywords: Photovoltaics; Semiconductors

Subject Areas: Materials, Physics, Energy


Instruments: B23-Circular Dichroism

Other Facilities: BL01-MIRAS at ALBA

Added On: 12/12/2024 10:04

Documents:
d4nr04269g.pdf

Discipline Tags:

Earth Sciences & Environment Sustainable Energy Systems Energy Physics Climate Change Electronics Energy Materials Materials Science Nanoscience/Nanotechnology

Technical Tags:

Spectroscopy Circular Dichroism (CD)