Simple donor-acceptor molecule with long exciton diffusion length for organic photovoltaics

Abstract

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Triphenylamine and some of its derivatives as versatile building blocks for organic electronic applications

“…Extending our initial approach based on the reduced‐size DA‐10 molecule (see below), Pshenichnikov and colleagues synthesized DA‐4 with an additional phenyl ring on the DCV unit. Compound DA‐4 demonstrated extremely long exciton diffusion lengths exceeding 25 nm in vacuum‐deposited films and was co‐evaporated with C 70 giving BHJ OSCs yielding a PCE as high as 5.11% …”

Triphenylamine/Tetracyanobutadiene‐Based π‐Conjugated Push–Pull Molecules End‐Capped with Arene Platforms: Synthesis, Photophysics, and Photovoltaic Response

“…Indeed, even the best photovoltaic performance obtained for Ph-1 remains quite low compared to the PV performance reportedf or analogous push-pull molecules with aD CV electron-withdrawing unit, [8d, e, 9, 10b, c, 11,13a, 15] one possible reason can stem from the significantly longers inglet excited state lifetimes of the later derivatives and hence their higher diffusion lengths. [15] As ac onsequence,T CBD-based push-pull molecules can be used as donor materials in OSCs,h owevert heir relative short singlet excited state lifetimesi nt he solid state, seems to limit their photovoltaicperformance.…”

“…Recently,t he substitution of the hydrogen atom of the DCV group by ap henylr ing gave rise to the new thermally stable derivative TPA-T-DCV-Ph that showed an unusual long exciton diffusion length (> 25 nm) and was used in vacuum-processed bulk heterojunction (BHJ) OSCs with C 70 leading to a PCE higher than 5%. [15] In this context,t he "click"-type [2+ +2] cycloaddition-retroelectrocyclization (CA-RE) reactionb etween an electron-rich alkyne and electron-deficient olefin, such as tetracyanoethylene (TCNE) leading to 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) derivatives, [16] has attracted our interest. This efficient reaction performed in the absence of catalyst under mild conditions allows for the introductiono fT CBD, as trong electron-accepting block (A), which is particularly convenient for the synthesis of thermally stable D-p-A push-pull conjugated molecules endowed with interesting opticalp roperties.…”

“…[13] Starting from TPA‐T‐DCV , minimal structural changes of: i) the TPA unit aiming at improving the hole transport properties, [14] ii) the π‐spacer toward extended electronic delocalization [13d] and iii) the strength of the electron‐withdrawing group A, [13b] led to enhanced PV performance. Recently, the substitution of the hydrogen atom of the DCV group by a phenyl ring gave rise to the new thermally stable derivative TPA‐T‐DCV‐Ph that showed an unusual long exciton diffusion length (>25 nm) and was used in vacuum‐processed bulk heterojunction (BHJ) OSCs with C 70 leading to a PCE higher than 5 % [15] …”

Excited state dynamics and exciton diffusion in triphenylamine/dicyanovinyl push–pull small molecule for organic optoelectronics

“…The first heating DSC scan (ESI, Sect. 1.2) shows high values of melting temperature (T m ) but significantly lower value of melting enthalpy (ΔH m ) compared to its non-fluorinated analog TPA-T-DCV-Ph 9 . This indicates that the fluorinated phenyl weakens intermolecular interactions that affect the molecular packing as it was previously reported for other fluorinated conjugated materials [23][24][25] .…”