Conformational distortion-harnessed singlet fission dynamics in thienoquinoid: rapid generation and subsequent annihilation of multiexciton dark state

Abstract

Singlet fission (SF) as a multiexciton generation process could potentially offset thermalization losses and boost the efficiency of photovoltaic devices. However, the scope of SF-active materials still remains rather limited...

Dark State of the Thiele Hydrocarbon: Efficient Solvatochromic Emission from a Nonpolar Centrosymmetric Singlet Diradicaloid

“…Singlet diradicaloids (SDs) are emerging as a promising class of molecular materials due to their potential multiple applications in several fields. , Many examples of SDs have been reported as conductive materials, , semiconductors in organic field-effect transistors (OFETs), − singlet-fission species for organic photovoltaics (OPV), − near-infrared (NIR)-absorbing chromophores, and dyes for nonlinear optics (NLO). , A widely underestimated property of these versatile compounds is their luminescence. ,− This is quite surprising since the first-ever synthesized SD, the Thiele hydrocarbon ( TH ) (Figure ), was described as fluorescent in solution and slightly oxygen- and light-sensitive . Probably, its photosensitivity and essentially quinoidal ground-state configuration limited the interest in the luminescence properties owned by the simplest para -quinodimethane ( p QDM) diradicaloid.…”

“…Moreover, the absence of chlorine atoms in meta positions undeniably affects the molecule processability, improving its solubility and favoring the thermal evaporation. The interest in the synthesis of highly fluorescent p QDM diradicaloids goes beyond their possible applications in optoelectronics or NLO , since the study of their luminescence can provide new fundamental insights into the nature of the emitting excited state , and its correlation with the ground-state open-shell character . Furthermore, their diradical character is attracting much interest for the possibility of controlling spin states through conformational changes. − …”

Robust singlet fission process in strong absorption π-expanded diketopyrrolopyrroles

“…3b). 39,40,43 In detail, Ex-DPP1 molecules exhibit slightly red shied and vibrational mode-increased absorption bands, and Ex-DPP2 molecules present an obvious red shied and enhanced absorption peak at the long wavelength. The spectral difference might be rooted in the different molecular packing geometries in these thin lms as discussed in the above structural analysis from single crystals and GIWAXS data (Fig.…”

“…Femtosecond transient absorption (fs-TA) and nanosecond laser ash photolysis (ns-TA) measurements were all performed using the previously described instruments and experimental conditions. [38][39][40] All the spectra were measured at room temperature if no further notication is given. Speciesassociated spectra and kinetic analyses of TA data were performed using a global tting method with lab-written MATLAB programs.…”

Quantitative Singlet Fission in Highly Stable Rubicene Skeleton: A Desirable Alternative to Acene Derivatives

“…X-ray diffraction (XRD) measurements confirm that these thin films are polycrystalline in nature and exhibit the intermolecular packing mode similar to those in crystals (Figure B). − Single-crystal data present an intermolecular packing mode suitable for SF occurrence, which features a close slip-stacked arrangement with π–π distance of ∼3.4 Å and transverse/longitudinal offsets of 3.62/0.55 Å (Figure C). It should be noted that Rc molecules show weak emission in thin film indicating that a more efficient photophysical process outcompetes the common fluorescence radiative transition and dominates the excited-state deactivation in solid aggregates. − …”