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In this work we compare experimental results of an industrial passivated emitter and rear cell (PERC) high volume pilot line production in the SolarWorld Innovations technology center with a simulation model based on 2D Sentaurus Device Simulations The PERC solar cell design shows in a well-controlled experiment a 1.1% absolute higher median efficiency compared to the aluminium back surface field (Al-BSF) solar cell reference group. We derive a calibrated simulation model by the characterization of cells and test structures. We show that the simulation model reproduces well the measured I-V data. In consequence this enables us to estimate the solar cell performance when an applied process or silicon wafer parameters will be changed for further optimization. In the second part of this study we investigate the impact of front and rear side recombination on the solar cell parameters by simulation and sensitivity analysis. We show that the quality of the local BSF underneath the local rear contacts has an important impact on the electrical solar cell performance.

With an innovative measurement technique termed “microwave detected photoconductivity” (MDP) it is possible to investigate defects of silicon wafers contact less and topographically by evaluating photoconductivity transients detected via microwave absorption. Thus it is possible to obtain the electrical key parameters (e.g. diffusion length and lifetime) in a contact less, non destructive and topographic way. The method is ideal for the investigation of process induced defects as a function of different processing steps. The inhomogeneities of the diffusion length map of the pure wafer correlate very well with the key parameter map of photosensor devices. Even more details of process induced failures of devices can be detected in detail with MDP. In general, the measurement conditions together with their evaluation can be tuned to nearly ‘predict’ properties and production yield of final devices for a given chain of processing steps.

Zusammenfassung Die Krankenhaushygiene am Marienhospital Osnabruck war zunachst uberrascht uber das Anliegen der Auszubildenden, diese Untersuchungen durchzufuhren. Im Nachhinein wurde sich die Hygiene jedoch mehr solcher Projekte im Rahmen der Ausbildung in den Gesundheitsberufen wunschen. Die Begleitung dieses Projekts war sehr interessant und aufschlussreich und hat hier im Hause zu einer weiteren Sensibilisierung im Umgang mit MRSA beigetragen. Die Ergebnisse der Untersuchung waren in dieser Form nicht erwartet worden und haben gezeigt, wie wichtig eine tagliche Desinfektion ist. Auch der Nachweis eines MRSA auf Turgriffen und in Eingriffen von Handschuh- und Mund-Naseschutz-Kasten lassen den Ruckschluss auf eine mangelhafte Handedesinfektion zu.

In this work we present our approach to realize an industrial process that allows cell efficiencies up to and above 21%. Based on a loss analysis we systematically investigate the feasible options to improve the efficiency with device simulations and production experiments. Subsequently we perform sensitivity analyses particularly for various silicon wafer materials to ensure stable process capability. Our best prototype process with optimized front and rear side passivation and enhanced laser contact patterning has demonstrated a maximum efficiency of 20.9% with a very high V OC of 670 mV on high-lifetime mono material. We were able to assemble 60-cell based modules with more than 305Wp.