Elucidating the effects of guest-host energy level alignment on charge transport in phosphorescent OLEDs

Sanderson, Stephen; Philippa, Bronson; Vamvounis, George; Burn, Paul L.; White, R. D.

doi:10.1063/1.5131680

Cited by 12 publications

(10 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…21 The KMC model was based on the work we have published previously. 20,22 Singlet generation was treated as instantaneous at the beginning of the simulation. A uniform generation profile was used, meaning that all molecules in the system had an equal probability of singlet generation.…”

Section: Methodsmentioning

confidence: 99%

Unraveling exciton processes in Ir(ppy)3:CBP OLED films upon photoexcitation

Sanderson

Vamvounis

Mark

et al. 2021

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

Emissive layers in phosphorescent organic light-emitting diodes commonly make use of guest-host blends such as Ir(ppy) 3 :CBP to achieve high external quantum efficiencies. However, while the Ir(ppy) 3 :CBP blend has been studied experimentally, crucial questions remain regarding how exciton diffusion is dependent on the distribution of the guest in the host, which can currently only be addressed at the atomic level via computational modeling. In this work, kinetic Monte Carlo simulations are utilized to gain insight into exciton diffusion in Ir(ppy) 3 :CBP blend films. The effects of both guest concentration and exciton density on various system properties are analyzed, including the probability of singlet excitons being converted to triplets, and the probability of those triplets decaying radiatively. Significantly, these simulations suggest that triplet diffusion occurs almost exclusively via guest-guest Dexter transfer and that concentration quenching of triplets induced by guest-guest intermolecular dipole-dipole interactions has a negligible effect at high exciton densities due to the prevalence of triplet-triplet annihilation. Furthermore, results for vacuum deposited morphologies derived from molecular dynamics simulations are compared to the results obtained using a simple cubic lattice approximation with randomly distributed guest molecules. We show that while differences in host-based processes such as singlet diffusion are observed, overall, the results on the fate of the excitons are in good agreement for the two morphology types, particularly for guest-based processes at low guest concentrations where guest clustering is limited.

show abstract

Section: Methodsmentioning

confidence: 99%

Unraveling exciton processes in Ir(ppy)3:CBP OLED films upon photoexcitation

Sanderson

Vamvounis

Mark

et al. 2021

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…The simulation algorithm has been described elsewhere. [38,39] We simulated the time dependent mobility for a range of energetic disorders that are typical for polymer:fullerene systems. The results (Figure S22, Supporting Information) show that the mobility during the transient response is expected to be 10-100 times higher than the steady state value.…”

Section: Strategy Toward Faster Response Speedmentioning

confidence: 99%

Toward Faster Organic Photodiodes: Tuning of Blend Composition Ratio

Saggar

Sanderson

Gedefaw

et al. 2021

Adv Funct Materials

Self Cite

View full text Add to dashboard Cite

The ability of a light‐sensor to detect fast variation in incident light intensity is a vital feature required in imaging and data transmission applications. Solution‐processed bulk heterojunction (BHJ) type organic photodiodes (OPDs) have gone through key developments, including dark current mitigation and longer linear dynamic range. In contrast, there has been less focus on increasing OPD response speed (f–3dB). Here, bulk heterojunction OPDs based on electron‐donating polymer poly[thiophene‐2,5‐diyl‐alt‐5,10‐bis((2‐hexyldecyl)oxy)dithieno[3,2‐c:3′,2′‐h][1,5]naphthyridine‐2,7‐diyl] (or PTNT) and electron‐accepting phenyl‐C71‐butyric acid methyl ester (or PC71BM) are reported. The intrinsic charge transport characteristics required for fast speed OPDs are discussed, and an analytical model for the same is developed. The OPDs present 0.8 MHz f–3dB under no applied voltage bias for a typical blend ratio of 1:1 by weight. It is shown that balanced electron and hole mobility is a critical criterion for faster speed OPDs, which can be realized by tuning the composition ratio of the bulk heterojunction. By tuning PTNT and PC71BM blend ratio, the f–3dB was successfully raised by more than quadruple to 4.5 MHz. The findings provide a tool to set device architecture for faster next‐generation light sensors.

show abstract

“…The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels of the commonly used host materials for NIR emitters are summarized in Table 1 , almost all host materials exhibit a larger HOMO-LUMO separation with respect to the guest molecules. Notably, the fine tuning of this alignment plays a fundamental role in tuning the carrier transport ( Sanderson et al., 2019 ).…”

Section: Approaches To Nir Light Generationmentioning

confidence: 99%

Non-toxic near-infrared light-emitting diodes

et al. 2021

View full text Add to dashboard Cite

Harnessing cost-efficient printable semiconductor materials as near-infrared (NIR) emitters in light-emitting diodes (LEDs) is extremely attractive for sensing and diagnostics, telecommunications, and biomedical sciences. However, the most efficient NIR LEDs suitable for printable electronics rely on emissive materials containing precious transition metal ions (such as platinum), which have triggered concerns about their poor biocompatibility and sustainability. Here, we review and highlight the latest progress in NIR LEDs based on non-toxic and low-cost functional materials suitable for solution-processing deposition. Different approaches to achieve NIR emission from organic and hybrid materials are discussed, with particular focus on fluorescent and exciplex-forming hostguest systems, thermally activated delayed fluorescent molecules, aggregation-induced emission fluorophores, as well as lead-free perovskites. Alternative strategies leveraging photonic microcavity effects and surface plasmon resonances to enhance the emission of such materials in the NIR are also presented. Finally, an outlook for critical challenges and opportunities of non-toxic NIR LEDs is provided.

show abstract

Elucidating the effects of guest-host energy level alignment on charge transport in phosphorescent OLEDs

Cited by 12 publications

References 28 publications

Unraveling exciton processes in Ir(ppy)3:CBP OLED films upon photoexcitation

Unraveling exciton processes in Ir(ppy)3:CBP OLED films upon photoexcitation

Toward Faster Organic Photodiodes: Tuning of Blend Composition Ratio

Non-toxic near-infrared light-emitting diodes

Contact Info

Product

Resources

About