Abstract Details


Xingyuan Shi

Postdog at Imperial College London

Xingyuan Shi

Postdog at Imperial College London

Abstract Name:

Seemingly ‘Trap-Free’ Charge-Transport Phenomena Mediated by Electronic Defects in Organic Semiconductors

Symposium:

Symposium A: Materials, Modelling, Simulation & Characterisation

Topic:

A1: Electronic Defects & Transport

Abstract Contributing Authors:

Xingyuan Shi, 1) Roderick C. I. MacKenzie, 2) and Jenny Nelson 1) 1 Department of Physics & Centre for Processable Electronics, Imperial College, London SW7 2AZ, United Kingdom 2 Department of Engineering, Durham University, Lower Mount Joy, South Road, Durham DH1 3LE, United Kingdom

Abstract Body:

We discuss how the presence of electronic defects can lead to apparently ‘trap-free’ (lowly dispersive) time-resolved carrier transport behaviour through carbon-based molecular semiconductors.

On the experimental front, we study the archetypal deep-blue-emitting polymer, poly(9,9-dioctylflourene) (PFO). PFO is chosen due to the processing-controllable variations in its chain conformation. This, in turn, affords the inclusion or exclusion of an energetically well-defined set of subgap states that can be reliably produced and verified [1]. 

Using a drift-diffusion model [2] capable of resolving charge carriers in both time and energy (i.e., with no assumption of the devices under quasi-equilibrium), we compare, side by side, experimental observations and numerical simulations. This way, we decipher the physical origin for the observed deceptively ‘trap-free’ electronic transport phenomena, which were obtained via time-domain probes [e.g., time-of-flight photocurrent (ToF) and transient space-charge-limited conduction (aka t-SCLC or “dark injection”)].

We conclude this contribution by highlighting the benefit of exploiting an array of carrier transport techniques that expose devices in vastly varying operating (therefore physical) conditions to reliably reveal the electronic properties of any given disordered solids.

[1] X. Shi et al., Phys. Rev. X. 9, 021038 (2019)

[2] OghmaNano – a freeware available at https://www.oghma-nano.com/download.php; original research article featuring core of the drift-diffusion numerical solver: R. C. I. MacKenzie et al., Adv. Energy. Mater. 2, 662-669 (2012)

Submission Type:

Talk

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