Self-Assembly of Poly(3-hexylthiophene)-block-polylactide Block Copolymer and Subsequent Incorporation of Electron Acceptor Material

Abstract

It is commonly accepted that in order to develop high-performance organic and/or hybrid organic−inorganic solar energy devices, it is necessary to use, among other components, an active donor−acceptor layer with highly ordered nanoscale morphology. In an idealized morphology, the effectiveness of internal processes including exciton generation and separation and charge carrier migration is optimized, leading to an efficient conversion of photons to electricity. With this idea in mind, we have rationally designed and developed an ordered nanoscale morphology consisting of self-assembled poly(3-hexylthiophene) donor domains of molecular dimension, each of them separated by fullerene C60 hydroxide acceptor domains. A poly(3-hexylthiophene)-block-poly(l-lactide) block copolymer was used as a structure-directing agent to pattern active material into ordered nanostructures. Using this intimate morphological control, one can begin to probe structure−property relationships with unprecedented detail with the ultimate goal of maximizing the performance of future organic/hybrid photovoltaic devices.

Block copolymer strategies for solar cell technology

“…Another study utilized a P3HT diblock with a degradable PLLA segment to form a vertically aligned lamellar structure with a period of $16 nm, as shown in Figure 19. 201 The etched PLLA region was backfilled this time by dip coating the film in an aqueous C 60 solution, to fill the voids between the P3HT regions. Evidence for quenching in the layer was measured by photoluminescence although no actual OPV devices were fabricated.…”

Block Copolymer Nanostructures for Technology

“…The coil block can be etched and the space refilled with the acceptor material. Botiz et al [85] and Boudouris et al [86] both demonstrated the possibility of generating structures in poly(3-hexylthiophene-block-lactide) (P3HT-b-PLA) by the removal of the PLA domains, with the former work also showing subsequent re-filling using fullerene acceptors and concomitant PL quenching. The wet procedures used to etch the PLA blocks introduce the problem of pattern collapse [87], which commonly occurs in the fabrication of high-aspect ratio nanostructures.…”

Renewable polymeric materials for electronic applications

“…As noted, PLA can be used as a template for nanopatterning and the morphology of the active layer can be controlled using a block copolymer template. Botiz et al 56 reported the enhancement of the donor/acceptor interface using poly(3-hexylthiophene) (P3HT)-b-PLLA. P3HT-b-PLLA was first annealed to form a lamellar structure with a periodicity of~8 nm.…”