In this study it is revealed that the light induced defects (LIDs) responsible for the fast degradation of hydrogenated amorphous silicon (a-Si:H) solar cells under light soaking are located at nanosized voids. This important breakthrough in identifying the local environment of LIDs has been achieved by detailed study of the relation between the nanostructure of a-Si:H and metastability of corresponding solar cell devices under light soaking. We propose that a useful tool to define the nanostructure of a-Si:H is to determine the size distribution of the volume deficiencies, which range from small hydrogenated vacancies up to nanosized voids. The processing window used to vary and control the nanostructure in dense a-Si:H is based on a hydrogen rich plasma at unconventional high processing pressures (~10 mbar). The dense absorber layers with different distributions of volume deficiencies are subsequently incorporated in solar cell devices. For the first time a clear relation between nanostructures of the a-Si:H absorber layer and the fast kinetics of the metastable LIDs of the solar cell during light soaking and thermal annealing is observed. The `fast' degradation (first 10 hours of light soaking) strongly correlates to the density of largest volume deficiencies in the a-Si:H matrix. The “slow” regime (10 tot 1000 hours of light soaking) appears to be independent on the nanostructure of the absorber layer. In addition, the fast metastable defect states are the first ones to be annealed out at relative low annealing temperatures (120-130 C). Although solar cells processed at higher pressure have the same long term degradation kinetics, their FF recovers much faster by thermal annealing when compared to the cells processed at standard low pressure and low hydrogen dilution conditions.@en

The effect of deposition temperature on the structural and optical properties of amorphous hydrogenated silicon (a-Si:H) thin films deposited by plasma-enhanced chemical vapour deposition (PECVD) from silane diluted with hydrogen was under study. The series of thin films deposited at the deposition temperatures of 50 ¿ 200°C were inspected by XRD, Raman spectroscopy and UV Vis spectrophotometry. All samples were found to be amorphous with no presence of the crystalline phase. Ordered silicon hydride regions were proved by XRD. Raman measurement analysis substantiated the results received from XRD showing that with increasing deposition temperature silicon-silicon bond-angle fluctuation decreases. The optical characterization based on transmittance spectra in the visible region presented that the refractive index exhibits upward trend with increasing deposition temperature, which can be caused by the densification of the amorphous network. We found out that the scale factor of the Tauc plot increases with the deposition temperature. This behaviour can be attributed to the increasing ordering of silicon hydride regions. The Tauc band gap energy, the iso-absorption value their difference were not particularly influenced by the deposition temperature. Improvements of the microstructure of the Si amorphous network have been deduced from the analysis.@en

Recent developments on scattering models based on the scalar scattering theory allow to estimate the angular intensity distribution and the haze in both transmission and reflection for nano-textured interfaces created by arbitrary materials. In this contribution, such a scattering model is combined with the opto-electric ASA simulation software and tested by simulating and measuring the external parameters and the external quantum efficiency of solar cells with different interface morphologies. This test shows that the scattering model is able to predict the influence of the nano-textured interfaces on the solar cell performance. The achievements presented in this manuscript can be used to search for nano-textured interfaces with optimized morphologies.@en