Influence Of Post-deposition Treatment Research Articles

Joule-Heating Annealing to Increase Organic Solar Cells Performance: A Comparative Study

In this work, we present our results on the influence of post-deposition treatments on the morphology and optical properties of photoactive films made of small molecules and their subsequent effect on the performance of photovoltaic (PV) devices. We have chosen DPP(TBFu)2:PC61BM as a benchmark model system and compared a novel joule-heating annealing (JHA) treatment with the widely used temperature annealing (TA) and solvent annealing (SVA) treatments. Detailed characterization of the morphology of the active layer and the performance of the devices suggests that JHA is a valuable post-treatment technique that provides fast information about the development of domains in the photoactive layer. Finally, in this context, solar cells on flexible indium tin oxide (ITO) substrates, made of polyethylene terephthalate (PET), were fabricated and analyzed.

Influence of Defect Post-deposition Treatments on poly-Si Thin-film Solar Cells on Glass grown by ECRCVD

AbstractThe epitaxial thickening of a thin polycrystalline Si (poly-Si) film (seed layer) is a promising approach to realize an absorber layer of a poly-Si thin-film solar cell on glass. Such cell concept combines the benefits of crystalline Si and the high potential for cost reduction of a thin-film technology. Here, we discuss the influence of post-deposition treatments on the properties of absorber layers grown by electron-cyclotron resonance chemical vapor deposition (ECRCVD) and the solar cell performance, respectively. After the absorber growth and prior to the emitter deposition, defect annealing was used to improve the structural quality of the absorber layers and to increase the doping efficiency. For this, we used rapid thermal annealing (RTA) processes as well as thermal annealing in a conventional quartz furnace. In order to avoid damaging of the glass, only short annealing times (up to 400 s) were applied at temperatures of up to 950 °C. Defect passivation treatments were carried out at temperatures of about 350 °C to passivate the remaining defects in the films by hydrogen. The impact of both treatments on the solar cell parameter will be discussed. Excellent VOC's of up to 361 mV were achieved without hydrogenation showing the high potential of ECRCVD-grown absorbers. Applying both treatments resulted so far in an increase of VOC of about 400 mV. Because of the fact, that both post-treatments (particularly hydrogenation) are still not yet optimized, further improvements can be expected.

The influence of defects and postdeposition treatments on the free carrier density in lightly phosphorus-doped large-grained polycrystalline silicon films

The influence of postdeposition treatments (rapid thermal annealing and hydrogenation) on the doping of large-grained polycrystalline silicon p+nn+ thin-film diodes on glass substrates is investigated using resistivity and impedance analysis measurements. Whereas in the lightly phosphorus-doped base region both treatments are found to cause an increase in the active doping concentration, hydrogenation decreases the active doping concentration of both heavily doped layers (Al and P). The different behavior is attributed to acceptorlike defects which are present in the nonhydrogenated base region in a similar concentration as the atomic phosphorus concentration and which are well passivated by hydrogenation. From posthydrogenation annealing experiments and temperature-dependent impedance analysis measurements, different temperature dependences and activation energies (depending on the posthydrogenation annealing temperature) are found for the lightly doped base region. The temperature dependences are quanti...

The influence of post-deposition treatment on the physical properties of CdTe films deposited by stacked elemental layer processing

Cadmium telluride thin films have been deposited on glass and glass/SnO 2/CdS substrates using the stacked elemental layer (SEL) technique. After the films were deposited, they were subjected to the conventional heat treatment in the presence of a CdCl 2/methanol solution. The samples were analyzed, before and after treatment, by X-ray diffraction, atomic force microscopy, cathodoluminescence and energy dispersive X-ray spectrometry. The results suggest that the treatment promotes grain growth, decreases defect concentration, and gives rise to the formation of a CdTe 1− x S x solid solution, which replaces the CdTe original layer. The existence of this solid solution was evidenced by a reduction in the lattice parameter relative to untreated samples and confirmed by EDS analysis of treated and untreated glass/SnO 2/CdS/CdTe structures.

Non-stoichiometry in thin film dilute tungsten bronzes: M xWO 3− y

Thin films of tungsten trioxide have been prepared in various ways which give rise to different optical behaviour. The white light optical absorption versus inserted lithium atom concentration is measured and followed as a function of time. The influence of post-deposition treatment in oxygen at 300°C is studied, and the results of these experiments support the key role of non-stoichiometry. Previous thin film structural studies are re-enforced here by a structural investigation of evaporated films using the atomic force microscope. These optical-insertion data are interpreted by means of a model which proposes that electron trapping occurs at crystalline shear plane boundaries (which account for the non-stoichiometry). The extent and rate of trapping is modelled, and the experimental results are consistent with the trapping rate being proportional to the lithium atom concentration in the films. The importance of minimising non-stoichiometry in electrochromic devices and in specimens of material for use in physical measurements is made clear.

Pyroelectricity in (Pb0·98Mn0·02)(Zr0·6Ti0·4)O3sputtered thin films

Abstract Manganese-doped lead-zirconate-titanate (PZT) thin films have been deposited on platinum-coated silicon by rf-magnetron sputtering from pressed powder targets. The films have been deposited without substrate heating. The amorphous films were then annealed in an oxygen flow. The structure of the films is rhombohedral. The dielectric, ferroelectric and pyroelectric properties are reported. The influence of post-deposition treatment and poling treatment on the pyroelectric coefficient are discussed.