Coherent two-dimensional electronic spectroelectrochemistry

Substituent-dependent absorption and fluorescence properties of perylene bisimide radical anions and dianions

“…Recently, after Rybtchinski's first observation of fluorescence for the parent core-unsubstituted PBI dianion, 27 we were able to disclose the first example of a fluorescence spectrum for the dianion of a tetraphenoxy-substituted PBI, utilizing a flow-cell setup that enabled the investigation of the emission as well as femtosecond and coherent two-dimensional (2D) electronic spectroscopy measurements. 33 The latter technique indeed points to another major application of PBI dyes as acceptors in donoracceptor dyads. Here, PBIs are the preferred acceptors due to the characteristic signature of the PBI radical anion bands in the NIR spectral range.…”

Ultrafast transient absorption spectroelectrochemistry: femtosecond to nanosecond excited-state relaxation dynamics of the individual components of an anthraquinone redox couple

“…Previous TA-SEC studies have employed a variety of electrodes and set-ups. These include: electrodes containing many holes (metal mesh or grid) 18,65,66 or just a single hole, 15,17 a ow cell arrangement where the electrode and spectroscopy components are spatially separated, 67 or a thin layer spectroelectrochemical cell incorporating sufficiently thin planar electrodes. 68 In the case of mesh/grid electrodes, especially metal electrodes, it is essential that the hole size is made large enough so there is no beam scattering, which can result in the production of charge carriers in the conduction band.…”

“…This leads to a reduced solvent window in aqueous solution and a detectable dissolved oxygen signal, when scanning cathodically. With a ow cell arrangement, 67 the range of systems available for study is limited due to the electrochemistry and spectroscopy components of the cell being spatially separated. Whilst sufficiently thin BDD lms grown on quartz [70][71][72] have been used for thin layer (steady-state) SEC experiments, the manufacturing process can be challenging.…”

Intersystem crossing of perylene bisimide neutral, radical anion, and dianion derivatives compared via ultrafast spectroelectrochemistry

“…25,[48][49][50] In contrast to the radicals, the dianions are fluorescent but with a significantly lower quantum yield compared to their neutral parents. 25,50,51 The transition from the lowest excited state to the ground state according to Kasha's rule has an unfavorable symmetry, which leads to a weak oscillator strength and results in an enhanced non-radiative relaxation pathway. The possibility to form stable radical anions and dianions with contrasting fluorescence properties can lead to applications in molecular switches.…”

“…Following few pioneering studies, the extension of spectroelectrochemistry to the ultrafast time scale came into operation in several groups. 15,[54][55][56][57][58][59][60][61][62][63][64] We designed a setup for flow-cell transient absorption and coherent 2D electronic spectroelectrochemistry in the visible regime 51 that will also be employed in the present study.…”