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27th European Photovoltaic Solar Energy Conference and Exhibition; 1519-1523, Solar cells with locally contacted rear surface exhibit a trade off between surface passivation and ohmic losses. In order to reduce the penalty in Fill Factor (FF) when long distances between contacts are used, we explore the use of a low temperature epitaxially grown n+ c-Si layer at the rear surface of n-type c-Si solar cells. Additionally, the passivation and contact formation are also developed at low temperature using phosphorus-doped silicon carbide films (SiCx) and laser processing. Firstly, we obtain an effective surface recombination velocity (Seff) on 3.5 Ω cm n-type c-Si surface as low as 3 cm/s for SiCx films deposited at 225 ºC. Next, we determine laser parameters that yield good quality n++ regions ready to be contacted. These regions exhibit a surface recombination velocity of 1500 cm/s that results in a final Seff value well below 100 cm/s even for short pitches. Regarding the epitaxial silicon layer (epi-Si), an electrically active donor density of 1.2x1020 cm-3 is determined. The combination of the epi-Si layer with the SiCx film leads to Seff of ~300 cm/s. This relatively high Seff value can be attributed to the high donor density that increases bulk recombination within the epi-Si layer. Finally, we compare c-Si heterojunction solar cells with and without the epi-Si layer. The introduction of an epi-Si layer improves FF from 72.5 % to 77.3 % with the same distance between contacts. However, open-circuit voltage significantly decreases due to a higher rear surface recombination velocity.

Importance: Owing to infrastructural and population characteristics, the prison setting is at increased risk for transmission of SARS-CoV-2 and for severe clinical outcomes. Because of structural and operational reasons, research in prison settings is challenging and available studies are often monocentric and have limited temporal coverage; broader-based research is necessary. Objectives: To assess the extent and dynamics of the COVID-19 pandemic within the prison system of a large Italian region, Lombardy, and report the infection prevention and control measures implemented. Design, Setting, and Participants: This repeated cross-sectional study was carried out from March 1, 2020, through February 28, 2021 (first wave, March-June 2020; second wave, October 2020-February 2021) in the prison system of Lombardy, which includes 18 detention facilities for adults. All incarcerated persons and the prison staff of the penitentiary system of the Lombardy region participated in the study. Exposures: The main exposures of interest were the weekly average number of incarcerated individuals placed in quarantine in single or shared isolation rooms, the rate of sick leave by symptomatic and asymptomatic prison staff reported to the prison occupational medicine department on a weekly basis, and the level of overcrowding. Main Outcomes and Measures: The primary outcome measures were weekly COVID-19 crude case rates, weekly test positivity rate, and the relative risk of acquiring the infection for prison staff, incarcerated persons, and the general population. Results: The study population comprised a mean of 7599 incarcerated individuals and 4591 prison staff. Approximately 5.1% of the prison population were women; demographic characteristics of the prison staff were not available. During the study, COVID-19 occurred in 1564 incarcerated individuals and 661 prison staff. Most of these cases were reported during the second wave (1474 in incarcerated individuals, 529 in prison staff), when stringent measures previously enforced were relaxed. During both epidemic waves, incarcerated individuals and prison staff had a higher relative risk for COVID-19 infection than the general population during both the first wave (incarcerated individuals: 1.30; 95% CI, 1.06-1.58; prison staff: 3.23; 95% CI, 2.74-3.84) and the second wave (incarcerated individuals: 3.91; 95% CI, 3.73-4.09; prison staff: 2.61; 95% CI, 2.41-2.82). Conclusions and Relevance: The findings of this study suggest that the prison setting was an element of fragility during COVID-19 pandemic, with a high burden of COVID-19 cases among both the incarcerated individuals and prison staff. The prison setting and prison population need to be included and possibly prioritized in the response during epidemic events.