Identifying high-mobility tetracene derivatives using a non-adiabatic molecular dynamics approach

Abstract

The search for conductive soft matter materials with significant charge mobility under ambient conditions has been a major priority in organic electronics (OE) research. Alkylated tetracenes are promising cost-effective candidate molecules that can be synthesized using wet chemistry methods, resulting in columnar single crystals with pronounced structural stability at and above room temperature. A remarkable characteristic of these materials is the capability of tuning the tetracene core intracolumnar stacking pattern and the crystal melting point via the side chain length and type modifications. In this study, we examine the performance of a series of alkylated tetracenes as hole conducting materials using a novel atomistic simulation technique that allows us to predict both the charge transport mechanism and mobilities. Our simulations demonstrate that molecular wires of alkylated tetracenes are capable of polaronic hole conduction at room temperature, with mobility values ranging up to 21 cm 2 V À1 s À1 , thus rendering such materials a highly promising choice for flexible OE applications. As regards the charge transfer robustness, two promising tetracene derivatives are identified with the capability of seamless inter-wire polaron delocalization, alleviating possible transfer bottlenecks due to local molecular defects. Our findings suggest that alkylated tetracenes offer an attractive route towards flexible columnar OE materials with unprecedented hole mobilities. † Electronic supplementary information (ESI) available: Description of the FOBSH methodology; systems under study; utilized force field and molecular dynamics simulations details; reorganization energy and charge transfer integral calculations details; classical force field validation results; inverse participation ratio time series for the TMT molecular crystal. See

Delocalised kinetic Monte Carlo for simulating delocalisation-enhanced charge and exciton transport in disordered materials

“…Existing methods can be broadly divided into atomistic ones and those based on effective Hamiltonians. Atomistic calculations track the dynamics of both the nuclear degrees of freedom (usually using molecular mechanics) and the electronic ones (using quantum equations of motion) [31][32][33][34][35][36][37]. Atomistic simulations do not have adjustable parameters, but they suffer from the considerable cost of tracking the atomic motion.…”

“…1 ps [34][35][36][37]. These capabilities enable remarkable simulations of layered organic crystals, which admit a twodimensional simulation and are ordered enough that mobilities converge rapidly.…”

Evolutionary chemical space exploration for functional materials: computational organic semiconductor discovery

“…S4, ESI † for details) for a series of functionalised tetracenes. 41 These results indicate a good correlation for the majority of structures across the range of mobilities, but occasional outliers where Marcus theory predictions are poor. Our intention here is to present the framework of the evolutionary material discovery approach within which the simple charge transport model can be replaced when new methods become available at an affordable computational cost.…”

“…Using Marcus theory in this manner is similar to other recent high throughput methods which have evaluated structures using these types of properties. 11 As an assessment of its predictive power against a more complete description of charge transport, we carried out comparisons of Marcus theory against mobilities from non-adiabatic molecular dynamics [36][37][38][39][40][41] (see Table S2 and Fig. S4, ESI † for details) for a series of functionalised tetracenes.…”

Evolutionary Chemical Space Exploration for Functional Materials: Computational Organic Semiconductor Discovery

“…11 As an assessment of its predictive power against a more complete description of charge transport, we carried out comparisons of Marcus theory against mobilities from nonadiabatic molecular dynamics [36][37][38][39][40][41] (see Table S2 and Figure S4, ESI † for details) for a series of functionalised tetracenes. 41 These results indicate a good correlation for the majority of structures across the range of mobilities, but occasional outliers where Marcus theory predictions are poor. Our intention here is to present the framework of the evolutionary material discovery approach within which the simple charge transport model can be replaced when new methods become available at an affordable computational cost.…”