Excitation Energy Transfer/Migration between Tris(8-hydroxyquinoline) Aluminum and Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] in Chloroform

Abstract

Excitation energy transfer/migration between fluorescent electron transport molecule tris(8-hydroxyquinoline) aluminum (donor) and fluorescent hole transport polymer poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (acceptor) were studied in chloroform solution at room temperature using steady-state and time-domain fluorescence measurements. The blend of this pair is widely used in the fabrication of organic light-emitting diode. The considerable overlap integral between the emission spectrum of donor and absorption spectrum of acceptor indicates high donor−acceptor interaction, and the effective enhancement of the acceptor fluorescence along with a decrease in fluorescence intensity of donor by exciting the donor states characterized the excitation energy transfer between them. Relatively faster decay of donor in the presence of a higher concentration of acceptor followed the Forster kind of long-range fluorescence resonance energy transfer, which is illustrated by the agreement in the values of the energy transfer parameters observed from the fluorescence decay analysis and the values calculated from the spectral overlap. However, at lower acceptor concentrations, the excitation energy migration and diffusion/intrachain interaction influence the kinetics, resulting in a significant difference in the observed and calculated value of the energy transfer parameters. The influence of intrachain and interchain interactions during nonradiative excitation energy transfer is confirmed by the donor and acceptor decay dynamics on increasing acceptor concentration in donor−acceptor solution. No evidence of excimer formation is noticed in the donor−acceptor solution.

Effect of Diffusion on Photo-Induced Excited-State Energy Transfer between Fluorescent Semiconducting Molecules: Tris-(8-hydroxyquinoline) Aluminum and 6,13-Bis (Triisopropylsilylethynyl) Pentacene

“…In our early study of FRET in the AlQ 3 –MEHPPV system, we found that at a low acceptor concentration, energy migration and energy transfer influence the kinetics of excitation energy transfer, resulting in a significant difference in the observed and calculated value of the FRET parameters. The excited-state decay time analysis confirms the effect of intrachain and interchain interactions during nonradiative excitation energy transfer in the donor–acceptor solution …”

“…Förster resonance energy transfer (FRET) is one of the most popular methods in organic electronics to increase the efficiency of electroactive parts. − The Förster theory is based on the concept of treating a fluorophore as an oscillating dipole, which can nonradiatively transfer excitation energy to another dipole with a similar resonance frequency through the long-range dipole–dipole coupling and is a distance-dependent phenomenon (depends on the sixth power of donor–acceptor separation) . The theory is applicable for the media in which the molecules are either stationary or the molecular diffusion and energy migration is sufficiently low.…”

“…The excited-state decay time analysis confirms the effect of intrachain and interchain interactions during nonradiative excitation energy transfer in the donor−acceptor solution. 14 Here, we examine the modification in the absorption and fluorescence properties of TIPS-P by FRET. The effect of donor and acceptor concentration on diffusion-modulated excitation energy transfer/migration from AlQ 3 (donor) to TIPS-P (acceptor) in the solution phase was studied by steadystate and time-domain fluorescence measurements.…”

Förster Resonance Energy Transfer between Fluorescent Organic Semiconductors: Poly(9,9-dioctylfluorene-alt-benzothiadiazole) and 6,13-Bis(triisopropylsilylethynyl)pentacene

“…FRET between fluorescent organic semiconductor donor−acceptor systems thus plays a vital role in increasing the efficiency of devices, including organic photovoltaic (OPV), organic lightemitting diodes (OLED), solar cell, etc. [6][7][8][9]21,22 EET between different fluorescent organic semiconducting polymers or molecules is reported in the literature to explain the performance and characterization of various electronic devices. 1−4 FRET pair of [poly(9,9-dioctylfluorene-alcoholbenzothiadiazole] (F8BT) and P3HT (poly-3-hexylthiophene) in a blend film show that singlet excitons of F8BT transfer their excitation energy very fast within a picosecond to P3HT polymer.…”

“…However, for higher acceptor concentration, EET follows the Forster mechanism of energy transfer. 9 In a recent work, 10 we reported the effect of diffusion on FRET between an n-type donor (AlQ 3 ) and a p-type acceptor 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-P) in a chloroform solution. This pair followed energy transfer by donor diffusion and an exciplex formation at low acceptor concentration.…”