Assessing molecular doping efficiency in organic semiconductors with reactive Monte Carlo

Area of Science:

• Materials Science
• Computational Chemistry
• Organic Electronics

Background:

• Molecular dopants enhance organic semiconductor (OSC) conductivity.
• Extracting structure-function relationships is challenging due to sensitivity to chemistry, processing, and morphology.
• Computational modeling offers a path to isolate fundamental relationships by treating reactivity and morphology evolution.

Purpose of the Study:

• To present the first computational study coupling molecular reactivity and morphology evolution in molecularly doped OSCs.
• To examine how dielectric properties, doping reaction thermodynamics, and dopant aggregation affect morphology and doping efficiency.
• To establish a rational design strategy for maximizing doping efficiency.

Main Methods:

• Employed Reactive Monte Carlo simulations.
• Investigated the evolution of OSC-dopant morphologies and doping efficiency.
• Analyzed the impact of dielectric constants, reaction thermodynamics, and dopant aggregation.

Main Results:

• Doping efficiency approaches unity in well-mixed systems with experimentally relevant dielectric constants.
• Reaction-induced aggregation occurs at experimental dielectric constants, consistent with insolubility.
• Simulations show decreased doping efficiency with increased dopant concentration, aligning with experimental observations.

Conclusions:

• Dopant aggregation significantly lowers doping efficiency in molecularly doped OSCs.
• Preventing dopant aggregation is a rational design strategy for enhancing performance.
• This work pioneers the integration of reactivity and morphology in multi-scale structure-function characterization for OSCs.