Flexible and fragmentable tandem photosensitive nanocrystal skins.

We proposed and demonstrated the first account of large-area, semi-transparent, tandem photosensitive nanocrystal skins (PNSs) constructed on flexible substrates operating on the principle of photogenerated potential buildup, which avoid the need for applying an external bias and circumvent the current-matching limitation between junctions. We successfully fabricated and operated the tandem PNSs composed of single monolayers of colloidal water-soluble CdTe and CdHgTe nanocrystals (NCs) in adjacent junctions on a Kapton polymer tape. Owing to the usage of a single NC layer in each junction, noise generation was significantly reduced while keeping the resulting PNS films considerably transparent. In each junction, photogenerated excitons are dissociated at the interface of the semi-transparent Al electrode and the NC layer, with holes migrating to the contact electrode and electrons trapped in the NCs. As a result, the tandem PNSs lead to an open-circuit photovoltage buildup equal to the sum of those of the two single junctions, exhibiting a total voltage buildup of 128.4 mV at an excitation intensity of 75.8 µW cm(-2) at 350 nm. Furthermore, we showed that these flexible PNSs could be bent over 3.5 mm radius of curvature and cut out in arbitrary shapes without damaging the operation of individual parts and without introducing any significant loss in the total sensitivity. These findings indicate that the NC skins are promising as building blocks to make low-cost, flexible, large-area UV/visible sensing platforms with highly efficient full-spectrum conversion.

[Efficiency factors in psychotherapy--specific and nonspecific influences]. / Wirkfaktoren der Psychotherapie--spezifische und unspezifische Einflüsse.

The effectiveness of psychotherapy is discussed especially concerning the problem of specific versus unspecific factors and their possible interdependence. After a critical review of the results of the evaluation research some important paradigmatic papers on the differential operation of psychotherapeutic methods were evaluated. As there are no doubts that psychotherapy is effective in general even if it was performed by untrained therapist the impact of the specific and the unspecific factors has been investigated. As a result there was no convincing proof for the efficiency of specific factors in psychotherapy. As a consequence the unspecific factors have to be considered as highly effective in psychotherapy. Some models of the relationship factors were demonstrated and discussed.