Liquid-phase crystallized silicon absorber layers have been applied in heterojunction solar cells on glass substrates with 10.8% conversion efficiency and an open-circuit voltage of 600 mV. Intermediate layers of SiO x , SiN x , and SiO x N y , as well as the a-Si:H precursor layer, were deposited on 30 cm × 30 cm glass substrates using industrial-type plasma-enhanced chemical vapor deposition equipment. After crystallization on 3 cm × 5 cm area using a continuous-wave infrared laser line, the resulting polysilicon material showed high material quality with large grain sizes. Index Terms-Heterojunction, liquid-phase crystallization, plasma-enhanced chemical vapor deposition (PECVD), thin-film silicon.

Research indicates that spectral distribution and the direction of the light received at the eye are relevant parameters in studies looking into non-image-forming effects. Nonetheless, lighting conditions are often described with vertical illuminance at the eye and correlated color temperature only, both of which are integral measurements that are not appropriate to give information about the spatial distribution of light and its spectrum. This article describes approaches for spatially and spectrally resolved measurements to properly quantify lighting conditions in research on nonimage-forming effects. The overview of measuring methods indicates that the spectral irradiance, when combined with a luminance image of the lighting setting, is an adequate measure in a large number of research approaches. Nonetheless, lighting conditions in experimental setups with different light sources or various surface reflectances require a higher resolution of detail. Four examples of devices are presented that can be applied in different experimental setups or lighting settings. A decision scheme is included to support the selection of the most suitable measuring equipment. The article concludes with a proposal for analysis and representation of the measurements.

In this study, various silicon dielectric films, namely, a-SiOx:H, a-SiNx:H, and a-SiOxNy:H, grown by plasma enhanced chemical vapor deposition (PECVD) were evaluated for use as interlayers (ILs) between crystalline silicon and glass. Chemical bonding analysis using Fourier transform infrared spectroscopy showed that high values of oxidant gases (CO2 and/or N2), added to SiH4 during PECVD, reduced the Si-H and N-H bond density in the silicon dielectrics. Various three layer stacks combining the silicon dielectric materials were designed to minimize optical losses between silicon and glass in rear side contacted heterojunction pn test cells. The PECVD grown silicon dielectrics retained their functionality despite being subjected to harsh subsequent processing such as crystallization of the silicon at 1414 °C or above. High values of short circuit current density (Jsc; without additional hydrogen passivation) required a high density of Si-H bonds and for the nitrogen containing films, additionally, a high N-H bond density. Concurrently high values of both Jsc and open circuit voltage Voc were only observed when [Si-H] was equal to or exceeded [N-H]. Generally, Voc correlated with a high density of [Si-H] bonds in the silicon dielectric; otherwise, additional hydrogen passivation using an active plasma process was required. The highest Voc ∼ 560 mV, for a silicon acceptor concentration of about 10(16) cm(-3), was observed for stacks where an a-SiOxNy:H film was adjacent to the silicon. Regardless of the cell absorber thickness, field effect passivation of the buried silicon surface by the silicon dielectric was mandatory for efficient collection of carriers generated from short wavelength light (in the vicinity of the glass-Si interface). However, additional hydrogen passivation was obligatory for an increased diffusion length of the photogenerated carriers and thus Jsc in solar cells with thicker absorbers.

Within a large joint research project aiming for characterizing the nonvisual effects of light (NiviL), AuReTim, a low-cost and extensible open-source portable psychomotor vigilance test using auditory stimuli was developed, tailored for field testing. Currently, an unprepared simple reaction time and a go/no-go paradigm using acoustic stimuli are implemented. AuReTim is based on inexpensive hardware, e.g., its core is a Raspberry Pi leveraging a touch screen as input. Its software is developed in Java™ using open-source libraries, therefore providing connectivity with other research setups, e.g., EEG, and easy extensibility with other stimulus paradigms. A simulation study proved the precise timing of AuReTim with limits of agreement between −1.86 and 1.67 ms. AuReTim combines the mobility of tablet-based psychomotor vigilance tests with the usability of conventional computer-based tests, which is especially helpful in field studies. AuReTim was successfully applied to study the effects of different lighting on alertness and proved to be a valuable tool for studies using the central nervous activation level as an outcome measure.

No abstract