Heterojunction devices, preparation

A polymer based on EDOT containing a perylenetetracarboxylic diimide unit has been prepared by electropolymerization of 250 [443]. The related absorption spectrum covers the visible range and extends up to 850 nm. Similarly, PV devices based on dyads 251 in which oligo(3-hexylthiophene)s are covalently linked to perylenemonoimide have been recently reported [444]. Preliminary results based on bulk heterojunction devices consisting of ITO/PEDOT-PSS/251 PCBM (l 4)/LiF/Al showed an open circuit voltage of 0.94 V and efficiencies of 0.33% (251, n=l) and 0.48% (251, =3) under standard test conditions (AM 1.5G, 1000 W m ). 

The reader is cautioned that band offsets have traditionally been hotly debated and are highly sensitive to individual measurements and materials preparation methods. The most reliable method for establishing the offsets has traditionally been to model the performance of heterojunction devices, which have performances that depend strongly on the offset values. Photoelectron spectroscopy is easier to use but more subject to experimental errors. The behavior that you observe may vary. 

The above results showed that the ZnO/Si interface prepared by magnetron sputtering is of high complexity and difficult to control. This explains why all attempts to develop photovoltaic devices with reasonable performance on basis of sputtered ZnO/Si heterojunctions have failed. This may be a particular problem of the deposition method used. Recently it was... 

Sintering is the most widely-used technique for CO2 impedimetric devices and the most reported material is the BaliOj-CuO mixed oxide. Some examples of BaliOs-CuO sintered devices can be found in the bibliography, such as those by Ishihara et al. (1992,1995). It was their original suggestion that the sensing mechanism in this mixed oxide involves the adsorption of CO2 in the heterojunction between the n-type BaliOj and the p-type CuO, which supposes p-n junction barrier energy decrease that leads to a capacitance variation in the material. They prepared BaliOj pellets by the calcination of an equimolar mixture of BaCOj and TiOj at 1200°C. The BaTiOj was mechanically mixed with a commercial metal oxide (CuO) without further... 

As shown in Figure 5.9, randomly mixed polymer-inorganic BHJ and ordered heterojunction (OHJ) are two common structures to prepare hybrid solar cells [44]. Similar to polymer-fullerene BHJ solar cells, polymer-inorganic hybrid BHJ solar cells (Figure 5.9a) can overcome the limitations of bilayer devices having small donor-acceptor interfacial area with inefficient exciton dissociation. NCRs can be surface modified to render them soluble in organic solvents (such as chloroform, toluene and chlorobenzene) to facilitate solution processability. Various surface... 

A p-n-heterojunction type device can be fabricated on the basis of the junction formed between poly(pyrrole) and PT derivatives (e.g. PT or PMT) [784]. A PODT/Cfio junction device with a photo-induced charge transfer between PODT and Cgo is shown in Fig. 22 [449]. Rectifying bilayer electrodes with sequential bilayer structures are prepared from any pair of PBT/poly(pyrrole) and poly(3-bromothiophene)/poIy(pyrrole) by anodic electropolymerization on platinum electrodes [785]. 

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