Silicon heterojunction metal wrap through solar cells – a 3D TCAD simulation study

Silicon heterojunction metal wrap through solar cells have the potential for high efficiencies in a simple process flow. However, the non-conformal deposition of the hydrogenated amorphous silicon emitter causes specific loss mechanisms of this cell concept. The emitter does not fully cover the inner via surface. As a consequence, the via surface is not passivated and the via metallization is in electrical contact with the silicon base. The resulting loss processes are determined in 3D TCAD simulations. While via related recombination losses are negligible even for highest surface recombination velocities, the resistive losses are found to be critical. The limit for the contact resistance between via metallization and silicon is in the range of 1 Ωcm2, depending on substrate doping and via diameter. Below this value, the cell performance significantly degrades. Finally, three different approaches for novel SHJ-MWT solar cells are discussed

Passivation of interfaces in thin film solar cells: understanding the effects of a nanostructured rear point contact layer

Thin film solar cells based in Cu(In,Ga)Se2 (CIGS) are among the most efficient polycrystalline solar cells, surpassing CdTe and even polycrystalline silicon solar cells. For further developments, the CIGS technology has to start incorporating different solar cell architectures and strategies that allow for very low interface recombination. In this work, we study and characterize ultrathin 350 nm CIGS solar cells with a rear interface passivation strategy. The rear passivation was achieved using an Al2O3 nanopatterned point structure. Using the cell results, photoluminescence measurements and detailed optical simulations based on the experimental results, we show that by including the nanopatterned point contact structure, the interface defect concentration lowers, which ultimately leads to an increase of solar cell electrical performance mostly by increase of the open circuit voltage. Gains to the short circuit current are distributed between an increased rear optical reflection and also due to electrical effects. Our approach of mixing several techniques allowed us to make a discussion considering the different passivation gains which has not been done in detail in previous works. A solar cell with a nanopatterned rear contact and a 350 nm thick CIGS absorber provided an average power conversion efficiency close to 10%.publishe

Secondary crystalline phases identification in Cu2ZnSnSe4 thin films: contributions from Raman scattering and photoluminescence

In this work, we present the Raman peak positions of the quaternary pure selenide compound Cu2ZnSnSe4 (CZTSe) and related secondary phases that were grown and studied under the same conditions. A vast discussion about the position of the X-ray diffraction (XRD) reflections of these compounds is presented. It is known that by using XRD only, CZTSe can be identified but nothing can be said about the presence of some secondary phases. Thin films of CZTSe, Cu2SnSe3, ZnSe, SnSe, SnSe2, MoSe2 and a-Se were grown, which allowed their investigation by Raman spectroscopy (RS). Here we present all the Raman spectra of these phases and discuss the similarities with the spectra of CZTSe. The effective analysis depth for the common back-scattering geometry commonly used in RS measurements, as well as the laser penetration depth for photoluminescence (PL) were estimated for different wavelength values. The observed asymmetric PL band on a CZTSe film is compatible with the presence of CZTSe single-phase and is discussed in the scope of the fluctuating potentials’ model. The estimated bandgap energy is close to the values obtained from absorption measurements. In general, the phase identification of CZTSe benefits from the contributions of RS and PL along with the XRD discussion.info:eu-repo/semantics/publishedVersio

Visualizing emotions with linearly parameterized facial expressions

The key challenge of affective computing is to translate subjective emotional experiences into measurable data. Most recent advances in that field have relied on facial expressions as indicators for inner emotional states. Our current understanding of these expressions is categorical, i.e. there are some subjective feelings that are understood to be indicated by specific faces. There is no agreed measure for their distance and no clear rule for how emotions can combine or do exclude. The computational processing of emotions therefore mostly relies on compositional approaches using intependent dimensions, like valence and arousal. However, these methods lack a consistent mapping to a facial expression that turned out so crucial for the identification of emotional states. This paper seeks to solve this problem by introducing a consistent facial visualization for a five dimensional model. A graphical representation as a comic style facial expression is provided in examples, explanations and code. It visualizes emotions in a comically exaggerated style, similar to the successful emojis used in electronic communication. All graphical parameters depend linearly on the input dimensions (valence, arousal, dominance, contempt and control). This might be a rough and crude method. It might not even be a good one, but it is at least something linear in the space of emotions. Empirical results from crowd workers confirm that the encoded emotional information can be recorgnized intuitively and without further training

Untersuchungen an CuIn(Ga)Se_2-Duennschichten und Solarzellen

The following topics were covered: materials properties of CuInGaSe_2, evaporation process, solar cell structure, photoluminescence, positron annihilation, XRD, SIMS, photoelectron spectra, optical properties, defects and phases, tempering of thin films, RTP layers, oxygen influence on the surfaces and volumes, sound treatments of the solar cell structure (WL)SIGLEAvailable from: http://www.iwi-iuk.org/dienste/TheO/ / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Visualizing emotions with linearly parameterizedfacial expressions

The key challenge of affective computing is to translate subjective emotional experiences into measurable data. Most recent advances in that field have relied on facial expressions as indicators for inner emotional states. Our current understanding of these expressions is categorical, i.e. there are some subjective feelings that are understood to be indicated by specific faces. There is no agreed measure for their distance and no clear rule for how emotions can combine or do exclude. The computational processing of emotions therefore mostly relies on compositional approaches using intependent dimensions, like valence and arousal. However, these methods lack a consistent mapping to a facial expression that turned out so crucial for the identification of emotional states. This paper seeks to solve this problem by introducing a consistent facial visualisation for a five dimensional model. A graphical representation as a comic style facial expression is provided in examples, explanations and code. It visualises emotions in a comically exaggerated style, similar to the successful emojis used in electronic communication. All graphical parameters depend linearly on the input dimensions (valence, arousal, dominance, contempt and control). This might be a rough and crude method. It might not even be a good one, but it is at least something linear in the space of emotions. Empirical results from crowd workers confirm that the encoded emotional information can be recorgnized intuitively and without further training