Chemical doping is crucial for the operation of organic (opto)electronic and electrochemical devices. This is typically achieved by adding dopant molecules to the polymer bulk, enabling high electrical conductivities. However, this process can result in poor stability and performance due to nonoptimal charge transfer and thin film morphologies. Besides, once the dopant molecules are incorporated, they tend to diffuse through the free volume between polymer chains or to escape during the heating steps, degrading both the electrical and mechanical properties of the semiconductor. In addition, the diffusion of dopant molecules could pose a risk when these materials are placed in contact with the human body like e.g., in the case of wearable sensors. Thus, molecular doping of organic semiconductors significantly limits their implementation into novel opto-/bioelectronics applications. In this presentation, we will report on our recent efforts to develop stable and highly conductive polymer blends based on mutual electrical doping. First, we will discuss the case of non-conjugated polymeric dopants and then move toward a new generation of conjugated polymer-donor/polymer-acceptor blends based on the effect of ground-state electron transfer in all-polymer heterojunctions. These molecular dopant-free systems hold promise for the development of next-generation opto-/bioelectronics devices, in particular targeting novel functionality, efficiency and power performance.

Toward dopant-free organic electronics

ACS Fall 2021

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