# Morphology Control in PDVT-10/DTCP Hybrid Films via Meniscus-Guided Cooperative Crystallization for High-Performance OFETs

## TL;DR

This paper shows how controlling the structure of hybrid films using a meniscus-guided method improves the performance of organic transistors.

## Contribution

A new method for morphology control in hybrid polymer films using a meniscus-guided approach is introduced to enhance OFET performance.

## Key findings

- DTCP in closed-ring form increased PDVT-10 film mobility to 2.44 cm² V⁻¹ s⁻¹.
- DTCP-o, typically insulating, improved mobility from 2.12 to 3.23 cm² V⁻¹ s⁻¹.
- Photoswitchable DTCP allows optical modulation of energy levels for photocontrollable OFETs.

## Abstract

The meniscus-guided coating (MGC) method was used to
prepare well-aligned
films of hybrid systems composed of the conjugated polymer poly­{3,6-dithiophen-2-yl-2,5-di­(2-decyltetra-decyl)-pyrrolo­[3,4-c]­pyrrole-1,4-dione-alt-thienylenevinylene-2,5-yl}
(PDVT-10) and a photoresponsive small molecule dopant,
dithienylperfluorocyclopentene (DTCP), at various concentrations
in their open-ring form (DTCP-o) or closed-ring (DTCP-c) form. The structures of the coated films were characterized
with polarized optical microscopy (POM), grazing-incidence X-ray diffraction
(GIXRD), and atomic force microscopy (AFM). The DTCP can
undergo reversible isomerization between a more twisted open-ring
form and a more conjugated closed-ring form under UV and visible light,
respectively. Both DTCP isomers were found to function
as morphology-modulating additives that facilitate cooperative crystallization,
an effect attributed to enhanced solution-phase molecular association,
which impacts the packing of the polymer film. Organic field-effect
transistors (OFETs) were fabricated from these films. The DTCP-c doping progressively enhanced charge transport, reaching the highest
mobility of 2.44 cm2 V−1 s−1 at 10 wt %. Notably, 3 wt % DTCP-o, typically considered
insulating molecule, increased PDVT-10 mobility from
2.12 to 3.23 cm2 V−1 s−1. This improvement is suggested to arise from the combined effects
of precise molecular alignment by the MGC method and a favorable HOMO–HOMO
energy level alignment predicted by DFT, enabling cooperative charge
transfer despite the nominally insulating nature of the open-ring
form. The photoswitchable DTCP provides a unique opportunity
to optically modulate frontier molecular orbital energy levels, thereby
opening up an avenue for designing electronic devices such as photocontrollable
OFETs.