Correlation between Molecular Stereostructure, Film Microstructure, and Electronic Structure of Polyfluorene and Fluorene Based Alternating Copolymers F8BT and PFO–DBT

Abstract

Identifying key parameters that can help control molecular ordering in the active layer of high-performance organic devices is an important topical issue. Finding a correlation between the spatial molecular structure of polymer backbones and the thin film's structural and optoelectronic properties is thus of utmost importance. In this paper, the influence of the backbone spatial structures of homopolymer PFO and copolymers F8BT and PFO− DBT with various stereoisomers varying by the up or down spatial orientation of individual chemical units in the comonomer on the film microstructure and electronic structure is studied. The computed energetics of the stereoisomers revealed at least two energetically favorable stereoisomers in both copolymers. These theoretical findings correlate with the thin film's crystallinity analyzed by the GIWAXS method, which showed ill packing in copolymers with stereoisomers. Thus, the molecular stereostructure was identified as a critical parameter that can help control molecular organization in active layers of organic photonic devices.

Internal conversion rate constant calculations considering Duschinsky, anharmonic and Herzberg–Teller effects

“…The most important MO coefficients are those involving the 2s, 2p x , 2p y , 2p z atomic orbitals of the X atom and the 1s atomic orbital of the H atom forming X-H bonds of the a stretching mode. 39,40 The sum in eqn (25) represents the overlap of the wave functions of the initial and final states. The expression for the rate constant in terms of the NACME is given by…”

“…22–24 Calculations of molecular photophysical properties can be very useful when designing the molecular structure of semiconducting polymers in OLED devices. 25…”

“…[22][23][24] Calculations of molecular photophysical properties can be very useful when designing the molecular structure of semiconducting polymers in OLED devices. 25 Recently, we calculated the vibronic spectra of 9,9,9',9'-tetramethyl-2,2'-bifluorene and 9,9,9',9',9 00 ,9 00 -hexamethyl-2,2'-7',2 00terfluorene, 26 which emit light in the blue region. OLEDs based on them have the color space coordinates of c. x = 0.33, y = 0.33 27,28 implying that they are very good candidates for luminophores of blue pixels.…”