Extraction of photogenerated charge carriers by linearly increasing voltage in the case of Langevin recombination

Charge extraction by linearly increasing voltage (CELIV) is a powerful and widely used technique for studying charge transport physics, particularly in disordered systems such as organic semiconductors. In this article, we show that CELIV photocurrent transients are strongly dependent on experimental conditions, such as the light intensity and absorption profile. With this in mind, we introduce a universal correction factor that qualitatively extends previously derived CELIV equations, allowing carrier mobility to be estimated at various photogenerated carrier concentrations and, most importantly, photogeneration profiles. In addition, we demonstrate how the CELIV technique can be conveniently used to determine precisely the presence of Langevin bimolecular carrier recombination

Double Injection Current Transients in a-Si:H

In this work we present results of both computer modelling and experimental studies of double injection current transients in amorphous hydrogenated silicon thin layers

Ultrafast Bimolecular Recombination in Nanocrystalline Hydrogenated Silicon

In the multilayers of hydrogenated nanocrystalline and amorphous silicon bimolecular recombination coefficient can be reduced in half, while in low-temperature hydrogenated nanocrystalline silicon samples it can be reduced by one order of magnitude. The similarity of the activation energies of both the bimolecular recombination (B) and the Langevin-type recombination (B$\text{}_{L}$) coefficients point to decisive role of tunneling in processes of meeting of electrons and holes, although the ratio B/B$\text{}_{L}$<0.01

X-ray imaging with scintillator-sensitized hybrid organic photodetectors

Medical X-ray imaging requires cost-effective and high-resolution flat-panel detectors for the energy range between 20 and 120 keV. Solution-processed photodetectors provide the opportunity to fabricate detectors with a large active area at low cost. Here, we present a disruptive approach that improves the resolution of such detectors by incorporating terbium-doped gadolinium oxysulfide scintillator particles into an organic photodetector matrix. The X-ray induced light emission from the scintillators is absorbed within hundreds of nanometres, which is negligible compared with the pixel size. Hence, optical crosstalk, a limiting factor in the resolution of scintillator-based X-ray detectors, is minimized. The concept is validated with a 256 × 256 pixel detector with a resolution of 4.75 lp mm−1 at a MTF = 0.2, significantly better than previous stacked scintillator-based flat-panel detectors. We achieved a resolution that proves the feasibility of solution-based detectors in medical applications. Time-resolved electrical characterization showed enhanced charge carrier mobility with increased scintillator filling, which is explained by morphological changes