Structure of Thin Films of [6] and [7]Phenacene and Impact of Potassium Deposition

Abstract

Organic semiconductors offer a flexibility in band gap tuning through different molecular lengths and have shown to be promising candidates for high‐performance electronic devices. While electronic properties have been extensively studied in many publications, the topic of thin film structure and molecular packing is still quite neglected. In this work, the thin film crystal structure of [6]phenacene (Fulminene) and [7]phenacene deposited on silicon substrates using the OMBD method as well as further studies with potassium deposition on [6]phenacene are investigated. Ex‐situ X‐ray and optical methods are employed to obtain an insight into the crystal structure and optical properties. The orientation of the molecules and the unit cell structure is calculated from the measured reciprocal space maps. Additionally, the influence of a possible interfacial doping mechanism by deposition of potassium on top of [6]phenacene is investigated. Thin films of [6]phenacene show a high crystallinity with a standing‐up configuration and a similar molecular structure and symmetry compared to [4]phenacene. [7]phenacene features two different apparently thickness‐dependent polymorphs (H and L) with a structure similar to [5]phenacene. These results reveal that odd/even parity, that is, even or odd number of benzene rings, directly influences the phenacene thin film structure.

Optical Absorption Properties in Pentacene/Tetracene Solid Solutions

“…To get a clearer picture of the changes that occur upon blending acene molecules and to generalize our results, we prepared sample sets containing either PEN or TET mixed with phenacene molecules, which interact weakly with the former. Closely related to acenes, phenacene molecules are also composed of benzene rings, but with the rings being fused in an angular fashion . Therefore, the molecular dimension along the short axis of the molecular plane of a given phenacene is slightly increased compared to its acene analogue.…”

“…Closely related to acenes, phenacene molecules are also composed of benzene rings, but with the rings being fused in an angular fashion. 84 Therefore, the molecular dimension along the short axis of the molecular plane of a given phenacene is slightly increased compared to its acene analogue. This results in larger in-plane lattice parameters, as can be seen in the structural analysis of the respective neat and mixed thin films, as shown in the Supporting Information.…”

Interpretable Deep-Learning Unveils Structure–Property Relationships in Polybenzenoid Hydrocarbons

“…As a result, there are multiple all-A PBHs but only one all-L PBH for each isomer family. Among these all-A compounds, polyphenacenes (i.e., “zigzag”-type structures; Figure A and D1) are a specific and well-known subset and have been quite extensively studied. − To the best of our knowledge, however, a systematic study has not been reported on the structure–property relationships of other all-A PBHs or on molecules containing mixtures of A and L motifs.…”

Thickness‐Dependent Energy‐Level Alignment at the Organic–Organic Interface Induced by Templated Gap States

“…For [6]phenacene, the Bragg reflection positions after deposition of 18 nm are moderately temperature dependent, leading to the unit cell parameters summarized in Table 1 and showing good agreement with a recently published crystal structure. [ 13 ] Figure 1d (bottom) shows the thickness dependence of V UC taking also the out‐of‐plane data into account. We find an overall decrease of V UC between 6 and 12 nm and a weak decrease between 12 and 18 nm.…”