Important parameters for the design and performance of thermally activated delayed fluorescence (TADF) emitters are the forward and reverse intersystem crossing rates between singlet and triplet states. The magnitude of these rates is determined from the prompt and delayed transient photoluminescence decay. It is demonstrated that this photoluminescence decay strongly depends on the initial photoexcited population density due to exciton–exciton annihilation processes. By kinetic modeling of the power‐dependent time‐resolved photoluminescence of the TADF emitter 9,10‐bis(4‐(9H‐carbazol‐9‐yl)‐2,6‐dimethylphenyl)‐9,10‐diboraanthracene (CzDBA), singlet–triplet annihilation and triplet–triplet annihilation are identified as the main loss processes with rate constants in the order of 10−17 m3 s−1. Neglecting these quenching processes leads to erroneous estimates of the (reverse) intersystem crossing rates.

Biohybrid photoelectrochemical systems in photovoltaic or biosensor applications have gained considerable attention in recent years. While the photoactive proteins engaged in such systems usually maintain an internal charge separation quantum yield of nearly 100%, the subsequent steps of electron and hole transfer beyond the protein often limit the overall system efficiency and their kinetics remain largely uncharacterized. To reveal the dynamics of one of such charge-transfer reactions, we report on the reduction of Rhodobacter sphaeroides reaction centers (RCs) by Os-complexmodified redox polymers (P-Os) characterized using transient absorption spectroscopy. RCs and P-Os were mixed in buffered solution in different molar ratios in the presence of a water-soluble quinone as an electron acceptor. Electron transfer from P-Os to the photoexcited RCs could be described by a three-exponential function, the fastest lifetime of which was on the order of a few microseconds, which is a few orders of magnitude faster than the internal charge recombination of RCs with fully separated charge. This was similar to the lifetime for the reduction of RCs by their natural electron donor, cytochrome c 2 . The rate of electron donation increased with increasing ratio of polymer to protein concentrations. It is proposed that P-Os and RCs engage in electrostatic interactions to form complexes, the sizes of which depend on the polymer-toprotein ratio. Our findings throw light on the processes within hydrogel-based biophotovoltaic devices and will inform the future design of materials optimally suited for this application.

annihilation (TTA) to form an emitting singlet [1,[6][7][8] and band-to-band recombination. [9,10] EL has even been observed in devices without such heterojunction, for which it was proposed that electrons could be injected directly into a low-energy triplet state, followed by emissive singlet exciton formation via triplet fusion. [7] However, it should be noted that EL at subgap voltages has been widely observed in diodes based on inorganic semiconductors, in which processes such as TTA likely do not play a role. [11][12][13][14] Here, we demonstrate that EL at subgap voltages is a universal feature of OLEDs. Even down to zero applied voltage, EL is theoretically present, which is the result of the recombination of diffused and thermally generated charge carriers. Consequently, for an ideal OLED without traps and Ohmic contacts, the electrical quantum efficiency (EQE, Γ EL ) for EL equals unity down to zero applied voltage. Experimentally, EL at voltages below the energy gap is clearly observed in OLEDs based on emitters with negligible energy difference between the singlet and triplet excited stated, ruling out energy up-conversion mediated by low-energy triplet states. Furthermore, also in OLEDs with a strongly reduced free carrier density due to trapping the EL at subgap voltages occurs, ruling out Auger processes that require high carrier densities.

In an evaporator, when a high-energy continuous electron beam impinges a copper target, it generates an atomic beam. It is observed that plasma is formed. The primary and the backscattered electrons from the surface of the target produce copper plasma by electron-impact ionization of the atoms. The plasma is of low temperature, weakly ionized and is present in a weak transverse magnetic field. The magnetic field is used to bend the electrons from the gun. The plasma flows in a direction that is perpendicular to the target surface and transverse to the magnetic field. The plasma expansion is weakly collisional. It decays along the flow direction due to cross-field diffusion.

Biophysical investigations require the covalent tagging of proteins to study their structure, dynamics, and biomolecular interactions. 1 A promising approach for the same involves tethering protein with the probe of interest. 2,3,4 For example, the installation of fluorophore and fluorescence