Data Science Guided Experiments Identify Conjugated Polymer Solution Concentration as a Key Parameter in Device Performance

Abstract

Curating and analyzing centralized data repositories is a valuable approach in resolving the issue of reproducibility, gaining new insights and guiding future experiments, especially in the field of nanomaterials research. In this work, a data set containing processing information and mobility values of 115 DPP-DTT-based organic field effect transistors (OFET) was constructed from 15 publications. A customized classification algorithm was applied to the data set to help identify a reduced design region for polymer solution concentration that would be more likely to result in improved hole mobility. Experiments performed to confirm the insights from the data curation exercise revealed a strong influence of solution concentration on the polymer chain excitonic interactions and electronic performance. Devices fabricated at the critical chain overlap concentration of 5 g/L in chlorobenzene resulted in improved hole mobility, and were in good agreement with the insights provided by the classification algorithm.

Dynamics of Preaggregation and Film Formation of Donor–Acceptor π-Conjugated Polymers

“…Semiconducting π-conjugated polymers are suitable materials for solution-processable electronics thanks to their high solubility and excellent film formability. , The solution process realizes lightweight, flexible, and low-cost devices. Polythiophene-based π-conjugated polymers, such as poly­(3-hexylthiophene) (P3HT) and poly­(2,5-bis­(3-tetradecylthiophene-2-yl)­thieno­[3,2- b ] thiophene) (PBTTT), are the most studied π-conjugated polymers. − The carrier mobilities of these polymers are at most 0.1–1 cm 2 /(V s), which is comparable to that of amorphous silicon. , On the other hand, an alternating copolymer consisting of electron-deficient and electron-rich parts, which is commonly called a donor–acceptor (D-A) π-conjugated polymer, has demonstrated far higher carrier mobility than those of conventional π-conjugated polymers. − Since such a D-A π-conjugated polymer possesses a rigid backbone and exhibits an intermolecular D-A interaction, the aggregated structure, which should be effective for carrier transport, can be formed in the thin film. For example, a typical D-A π-conjugated polymer, poly­[2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole- alt -5,5-(2,5-di­(thien-2-yl)­thieno­[3,2- b ]­thiophene)] (PDPP-DTT), actually demonstrates the carrier mobility exceeding 10 cm 2 /(V s) .…”

Competing single-chain folding and multi-chain aggregation pathways control solution-phase aggregate morphology of organic semiconducting polymers

“…Most bonded parameters for bond lengths, angles, and dihedrals were taken directly from the OPLS force field for equivalent atom types, [59][60][61][62][63][64][65] while the equilibrium bond lengths and angles were obtained from the quantum-chemistry optimised geometry of the monomer. The exceptions were the bond stretching po- (17) and coloured by their site type. To preserve the backbone geometry of the AA representation, two dierent site types for the thiophenes (1 and 7) and imides (2 and 6) were dened, which have the same non-bonded and bond length parameters, but dierent bond angle parameters.…”

“…This choice was motivated by recent work that showed the concentration of a polymer solution relative to the polymer overlap concentration to be a key predictor of OSC device performance due to its effect on the extent and type of aggregation. 17 Making the crude approximation of ideal chains gives φ * ∝ 1/N 1/2 for polymer chain length N, and so constant φ V /φ * corresponds to constant φ V N 1/2 . The concentrations that gave the same φ V N 1/2 as the experimental system of 30mers at 5 g/L were 4 g/L for 40mers, 6 g/L for 20mers and 8.5 g/L for 10mers.…”

“…It is important to note here that c † scales very differently with N compared with the overlap volume fraction φ * , which has been used previously 17 to predict aggregation properties. The work of ref.…”

“…Fig.1Chemical structure of the P(NDI2OD-T2) monomer with the CG model overlaid. CG sites are labelled(17) and coloured by their site type. To preserve the backbone geometry of the AA representation, two dierent site types for the thiophenes (1 and 7) and imides (2 and 6) were dened, which have the same non-bonded and bond length parameters, but dierent bond angle parameters.…”