Increasing the horizontal orientation of transition dipole moments in solution processed small molecular emitters

Abstract

The transition dipole moments of the small molecular emitters in a polyfluorene host matrix align strongly in the plane of the film, when deposited from solution and even more when thermally annealed.

Bis(arylimidazole) Iridium Picolinate Emitters and Preferential Dipole Orientation in Films

“…The experimental angular dependencies of the p-polarized photoluminescence intensities were used as the input for optical simulations using the software OrientExpress. 38 The angular emission profile of the vertical and horizontal radiating dipoles is simulated based on the thickness and (anisotropic) refractive indices of the layers and the substrate. Hereby, an even distribution of the emitters across the emitting layer is assumed, and the intensities of the contributing dipoles are added accordingly.…”

Solution‐processable thermally activated delayed fluorescence emitters for application in organic light emitting diodes

“…and Senes et al . PL spectra of film samples were measured with PL spectrometers (FluoroMax‐4, Horiba Scientific, Japan). The excitation wavelengths for PL and PLQY measurements were 340 nm, which correspond to absorption peak‐top of the host material.…”

The interplay of interfaces, supramolecular assembly, and electronics in organic semiconductors

“…Controlling emitter orientation has thus been the subject of extensive study in recent years. A number of factors have been shown to influence the alignment of emitter molecules with respect to their substrate, including the choice of host [18,86], the shape of the emitter molecule [14,18], strength of interactions with the substrate [14,82,83], emitter chemical structure [87], the presence of permanent dipole moments [88], processing technique [87,89], and temperature [14,15,17,56,[90][91][92][93].…”

“…[11][12][13][14][15]), of semiconducting molecules displaying preferential alignment at interfaces can be found in the literature, but few general rules for predicting interfacial orientation from chemical structure or processing conditions appear to exist. Many factors have been implicated in control of interfacial orientation, including, among others, molecular shape [14,[16][17][18], the presence, length, and composition of side chains [8][9][10]19], backbone planarity [20], temperature [14,15,17], and solvent choice [14,20,21] and understanding the reasons behind these factors is important for the rational design of high performing organic semiconductors.…”