Growth, morphology and structure of mixed pentacene films

Abstract

This work investigates the evolution of structure and morphology of pure and co-evaporated thin films, as a function of pentacene concentration in a solid host of p-terphenyl.

Comparison of organic and inorganic layers for structural templating of pentacene thin films

“…This rate was chosen as it is the highest rate at which the bulk phase is minimised compared to the desired thin film phase, based on our previous work on non-templated films. 41 The film thicknesses and rates were monitored using quartz crystal microbalance sensors placed near the sources and substrates. The substrates were either kept at room temperature during deposition, or heated using quartz lamps, with the temperature monitored by a thermocouple placed near the substrate.…”

“…The inset in Figure 2a shows that the intensity of the (001) plane of the thin film phase (TF) of pentacene is suppressed with an enhanced contribution from the bulk phase (B) of pentacene. As the bulk phase peak was reported to appear at an angle ψ = 5°, 41,49 this suggests the pentacene molecules have a mosaicity that extends over a range of at least 5° as a result of the PTCDA underlayer. On the other hand, both CuI-templated pentacene films show a transition to a new molecular orientation with the presence of three additional planes in the region 2θ = 27-30°.…”

“…The pentacene films deposited on silicon consist of irregularly shaped crystals with an average size of 397 ± 196 nm ( Figure 1a), which is in good agreement with literature. 41,46 The error on the lateral grain size, given as a standard deviation, is significant, representing a wide size distribution and the limitations of grain boundary determination due to the close 1-20and (120) observed with the pentacene powder diffraction pattern (CCDC 665900). 26 The silicon substrate peak is indexed with *.…”

“…28 Previous work has reported the 0.5 Å/s deposition rate forms films consisting of two pentacene polymorphs: thin film phase and bulk phase. 41 In the dominant thin film phase, the two inequivalent pentacene molecules align to the substrate surface at angles of 86.6° and 88.7°. 28 High crystallinity and texture is also observed in the CuI film at both room temperature and 200°C with the XRD pattern consisting of the (111) plane with a minor contribution from the higher order (222) plane indicative of long range order ( Figure 2b).…”

Structure Dependence of Kinetic and Thermodynamic Parameters in Singlet Fission Processes

“…Here we explore the effect of the relative molecular orientation on the energy landscape of a well-defined pentacene system. 40 We investigate the dissociation kinetics in a dilute system where excited state diffusion is likely suppressed. The kinetic parameters are obtained as a function of temperature and pentacene concentration to identify variations in the dynamics of the parallel, specifically slip-stacked, and herringbone configurations.…”