Fine-Tuning the Microstructure and Photophysical Characteristics of Fluorescent Conjugated Copolymers Using Photoalignment and Liquid-Crystal Ordering
Simultaneously achieving high-quality uniform alignment over a large area and high-resolution bespoke spatial patterning of molecular orientation is long-sought yet challenging, despite the essential role in generating bio-inspired organic systems, miniaturized light modulation, integrated photonic circuits, directed excitation energy transfer and relaxation, etc. Within this featured paper, Dr. Yuping Shi at MPI-P and his coworkers report a research breakthrough made along this line, in terms of the successful fabrication of large-area extended monodomain (semi-)crystals of semiconducting polymers via the development of a novel photoalignment technique.
The photoaligned large monodomain films of solution-processed polymer semiconductors exhibit a highly desirable monodomain texture (that is, no domain boundary, rather than conventional multidomain textures) and near-unity order parameters, while on-demand spatial patterning of the domain texture has been found to “self-dope” the otherwise amorphous polymer matrix that resembles an efficient host–guest system for bio-mimicking certain structural basis and energy-harvesting properties of naturally occurring photosynthetic protein complexes. These polymer monodomains demonstrate strong linearly polarized emission, whilst also promoting extra emissive interchain excited states and effectively suppressing nonradiative energy losses as compared to the non-aligned films.
Moreover, a multi-level photoaligning process, e.g. working together with two‐photon infrared laser writing or masked non-contact activation of polarized UV light, is showcased to enable submicron spatial patterning of polymer/molecular orientation, hence allowing for a new degree of freedom to fine-tune the structure-function-property relationship in a broad range of advanced organic devices and functional structures.
