Latent Pigments Strategy for Robust Active Layers in Solution-Processed, Complementary Organic Field-Effect Transistors

TL;DR

This paper introduces a latent pigment strategy using thermally cleavable molecules to produce insoluble, robust active layers in solution-processed organic FETs, enhancing device stability and manufacturing flexibility.

Contribution

It demonstrates the use of tert-Butyloxycarbonyl functionalized molecules for creating insoluble, high-mobility semiconducting layers that withstand aggressive processing conditions.

Findings

Thermal cleavage densifies films and improves charge mobility.

Insoluble layers show high robustness to processing solvents.

Enhanced stability enables more complex device fabrication.

Abstract

Solution-processed organic semiconductors enable the fabrication of large-area and flexible electronics by means of cost-effective, solution-based mass manufacturing techniques. However, for many applications an insoluble active layer can offer technological advantages in terms of robustness to processing solvents. This is particularly relevant in field-effect transistors (FET), where processing of dielectrics or barriers from solution on top of the semiconductor layer typically imposes the use of orthogonal solvents in order not to interfere with the nanometer thick accumulation channel. To this end, the use of latent pigments, highly soluble molecules which can produce insoluble films after a post-deposition thermal cleavage of solubilizing groups, is a very promising strategy. In this contribution, we demonstrate the use of tert-Butyloxycarbonyl (t-Boc) functionalized diketopyrrolopyrrole and perylene-diimide small molecules for good hole and electron transporting films. t-Boc thermal cleavage produces a densification of the films, along with a strong structural rearrangement of the deprotected molecules, strongly improving charge mobility in both p- and n-type FET. We also highlight the robustness of these highly insoluble semiconducting layers to typical and aggressive processing solvents. These results can greatly enhance the degree of freedom in the manufacturing of multi-layered organic electronic devices, offering enhanced stability to harsh processing steps.