Ultrafast Photoinduced Electron Transfers in Platinum(II)-Anthraquinone Diimine Polymer/PCBM Films

Abstract

Two fluorescent polymers ([Pt]-(AQI(BM-PA) x )) n ([Pt] = trans-bis(ethynylbenzene)-bis-(tributylphosphine)platinum(II); AQI = anthraquinone diimine; BMPA = bis(para-methoxyphenyl)amine), P1 (x = 1; τ F ≤ 8 ps) and P2 (x = 2; τ F = 10 ps, 298 K), were prepared and investigated as thin films in the presence of phenyl-C 61butyric acid methyl ester (PCBM) to probe the photoinduced electron transfer processes using steady-state and timeresolved fluorescence and femtosecond-transient absorption spectroscopy (fs-TAS). P1 and P2 undergo an efficient oxidative photoinduced electron transfer (Px* + PCBM → Px +• + PCBM −• ; x = 1, 2) in solution and as films. Based on fs-TAS, the time scale for the photogenerated charge separated state forms within the excitation pulse (i.e., ≤150 fs). During the course of this study, the nature of the lowest energy emissive excited state was identified as a charge transfer state defined as [Pt] → AQI (major component) and BMPA → AQI (minor component) with the aid of density functional theory (DFT) and time-dependent DFT computations.

A Fused Poly(truncated rhombic dodecahedron)-Containing 3D Coordination Polymer: A Multifunctional Material with Exceptional Properties

“…For triplet excited states, this phenomenon has also been observed for platinum(II)-containing organometallic conjugated polymers. 58,59 In these cases, the low-lying excited states are charge transfer ones originating from the conjugated chain (λ emi > 750 nm), whereas the upper triplet excited state, T n , stems from a localized state of the platinum(II) fragment (λ emi = 450 nm). Moreover, the short-excited state lifetime of this upper T n emission (<100 ps) in CP2 is also consistent with the generally rapid nonradiative depletion of the upper excited states.…”

Nonconjugated Biocompatible Macromolecular Luminogens for Sensing and Removals of Fe(III) and Cu(II): DFT Studies on Selective Coordination(s) and On‐Off Sensing

“…Intrinsic fluorescence in nonaromatic macromolecular luminogens depend on several structural attributes, including N-branching enhanced rigidity and astricted interior mobility, [18][19][20][21] along with strategic selection of monomers and polymerization technique. [22] Indeed, a monomer bearing tertiary amide side chain should endow more rigidity and fluorescence of polymeric luminogens compared to monomers comprising primary or secondary amide functionality.…”

Triplet Excited-State Energetics and Dynamics in Molecular “Roller Wheels”

“…Much of the attention in the design of triplet generating OPV materials has been focused on triplet sensitization of conjugated polymers utilizing doped or pendant chromophores (organic n → π* or transition metals). , Other strategies of directly generating triplet excitons within pure OPV organic structure involve combinations of electron-rich and electron-poor units in alternating fashion, with a covalently attached heavy metal atom (ion) for enhanced intersystem crossing (ISC). ,− The best-researched strategies are generated from push–pull organometallic platinum-bisacetylide-containing polymers and small molecules in OPVs and OLEDs, where two sterically bulky platinum-bisacetylide moieties are placed at both ends of a linear multiaromatic organic chromophore, forming structures resembling that of “dumbbells”. ,, Extensive studies on these materials have revealed how structural changes can alter the band-gap, morphology, triplet exciton dynamics, and device performance. The results of such studies have produced OLEDs with tunable emission over the visible range, as well as OPVs with efficiencies of ca.…”