Study of the influence of the molecular organization on single-layer OLEDs' performances

TL;DR

This study investigates how the molecular organization within single-layer OLEDs influences their efficiency, showing that disordered molecular arrangements improve performance by optimizing charge transport and recombination.

Contribution

It introduces new silole derivatives with adjustable flexibility to systematically study the impact of molecular packing on OLED performance in a single-layer architecture.

Findings

Crystalline-like organization leads to high current density but low luminance efficiency.

Disordered molecular assemblies enhance performance by improving charge transport.

Molecular packing significantly affects OLED efficiency and recombination processes.

Abstract

The authors synthesized three new silole derivs. with incrementally flexible structure to tune their packing ability and therefore study the influence of the mol. organization in single-layer OLEDs. This architecture was chosen since the absence of org. layers interfaces allows a better evaluation of the role of the mol. arrangement in the active layer. The examn. of the EL properties gives evidences of the prominent role of the mol. organization on the OLED efficiency. A cryst.-like organization of the mols. allows high c.d. but low luminance efficiency since an excessive electron current flow is involved compared to the hole one, and the recombination rate is poor. On the contrary, disordered assemblies of mols. allows better performances by avoiding unfavorable p-stacking, while keeping good intermol. orbital overlaps to support charge carrier transport.