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8th World Conference on Photovoltaic Energy Conversion; 95-97, We present passivating contacts for silicon solar cells using an interfacial layer of SiO2 grown by immersion in hot HNO3 and in-situ doped layers of both polarities grown by plasma enhanced chemical vapor deposition (PECVD). The doped layers are crystallized and their dopants are activated by rapid thermal processing (RTP) with a temperature profile similar to the firing of screen-printed metallization pastes, hence we call them fired passivating contacts (FPCs). After RTP, we apply hydrogenation to passivate defects, using thermal release of hydrogen from a SiNx reservoir layer during hot plate annealing at 450°C. We find that the kinetics of the hydrogenation process is characterized by a fast process associated to the passivation of defect states at the Si/SiO2 interface and a slower process likely related to the hydrogenation of bulk defects that are formed during RTP in the floating zone wafers used in this experiment. Despite the issue with bulk defects, we test the suitability of the FPCs for solar cells by depositing n- and p-type layers on the textured front and on the flat rear of single-side textured wafers, respectively. After co-processing in a single RTP step, we apply the optimum hydrogenation conditions identified above. Using an ITO/Ag metallization made at low temperature to fabricate proof-ofconcept solar cells, we obtain efficiencies up 20.5%.

High-temperature compatible passivating contacts based on phosphorus doped polysilicon (poly-Si(n)) on a thin silicon oxide, employed on the rear side of bifacial n-PERT like solar cells provide an efficiency increase while being compatible with current photovoltaic manufacturing processes, including the metallization process. However, a simple and cost-effective method for poly-Si(n) deposition is still elusive. Herein, we demonstrate DC-sputtering as a scalable and single side technique for poly-Si(n) manufacturing. First, it is demonstrated how DC-sputtered poly-Si(n) can provide high passivation (iV(oc) > 730 mV) and low contact resistivity (rho(c) < 20 m omega cm(2)) when metallized by means of screen printing and firing through of Ag paste. Then, M2-sized bifacial n-PERT solar cells featuring the developed DC sputtered poly-Si(n) at the rear side and a homogenous front side B-emitter reaching a certified efficiency of 22.8% are demonstrated. Quokka simulations based on the developed DC sputtered poly-Si(n) indicate a potential up to 24.8% with an upward potential upon optimization of the front side emitter. This work highlights the feasibility of sputtered poly-Si(n) as an enabler for high-efficiency n-type solar cells.

In this article, we investigate the contact resistivity of p -type passivating contacts for silicon solar cells. Our contact structures are compatible with firing, a rapid annealing process similar to the one used for sintering of the screen-printed metallization in solar cell manufacturing. We find that the short firing process crystallizes the doped layers and incorporates active boron dopants up to the solubility concentration at the chosen firing temperature. The dependence of our contact resistivities on carrier density and temperature suggest that the hole transport is a combination of tunneling through the oxide at the wafer surface and of thermionic field emission over the Schottky barrier to the metallization. For ideal firing conditions, we find implied open-circuit voltages up to 720 mV and contact resistivities as low as 15 m·Ω·cm2.

We investigate bulk and interface recombination in crystalline silicon with p-type fired passivating contacts. These consist of a chemical oxide and an in-situ doped layer of SiCx with low carbon content. Following a rapid thermal annealing to activate the dopants in the SiCx layer, we observe the formation of bulk defect states close to one of the band edges at temperatures between 450 and 700 degrees C. At temperatures of 800 degrees C and above, these bulk defects are increasingly cured. At the same time, the surface passivation provided by the interfacial oxide is increasingly deteriorated at temperatures above 800 degrees C, eventually permitting the injection of a recombination current into the SiCx layer. Consequently, there is a trade-off for the effective minority carrier lifetime with an optimum between 800 and 830 degrees C. We develop a formalism that distinguishes recombination through shallow bulk defects from the recombination current at the surface in a plot of the effective lifetime tau(eff) over the ratio n/p.

Introduction Central line-associated bloodstream infections (CLABSI) remains a high risk for burn patients due to their compromised integumentary system. Additionally, identifying bloodstream infections secondary to a burn infection versus a central line remains a challenge. Literature review suggests multidisciplinary CLABSI bundles (MCB) demonstrate reduction of CLABSIs. This research looks at the use of a MCB compared to the application of the standard CLABSI bundle alone reduce CLABSI incidence and standardized infection ratios over the past two years in the Burn Center. We hypothesize a MCB will have sustained CLABSI SIR and incidence reduction over time. Methods Infection Prevention & Control CLABSI data collection on all burn patients pre-intervention (2017-2018) and post-intervention (2019-2020) were performed as a quality improvement project; IRB was not obtained. In addition to the CLABSI Bundle (optimal site, aseptic insertion, aseptic maintenance, timely removal, & education), MCB was also implemented in Qtr. 1, 2019. MCB includes necessity of line discussion during daily and multidisciplinary rounds, strategic blood culture collection upon admission/transfers for patients with existing central line, improved nursing and provider documentation of burn infection per CDC definitions, integration of CLABSI reviews in tiered Burn Quality Improvement Program, and universal zero CLABSI goal setting for RNs. Two-sample t-test will be used to compare results pre-intervention (2017-18) & post-intervention (2019-20). CLABSI incidence and standardized Infection ratio will be illustrated per year. Results The post-intervention CLABSI SIR data (M= 0.08, SD=0.11) significantly improved when compared to the pre-intervention CLABSI SIR data (M= 0.77, SD= 0.169), t(2)=4.72, p=0.02. The post-intervention CLABSI incidence data (M=0.5, SD=0.70) significantly improved when compared to the pre-intervention CLABSI incidence data (M=4.5, SD= 0.70), t(2)= 5.65, p= 0.01 Conclusions The combination of the CLABSI bundle with the MCB demonstrated favorable CLABSI SIR and incidence reduction, as literature suggests. Implementing multimodal, multidisciplinary interventions must be a priority for sustained CLABSI reduction. Considerations for future studies should measure length of catheter days, incidence of positive blood cultures on admission/transfers for patients with existing central lines, and incidence of burn infection rates with positive blood culture and an existing central line.

Introduction An institutional Burn Intensive Care Unit (ICU) Rounding Tool was implemented for both quality improvement data collection and trainee education. Forms are completed by trainee team members daily for all critically ill patients prior to teaching rounds. Gathered data are structured to facilitate evaluation of patient volume status, sepsis risk and ventilator management. The forms are then used to guide discussion among students, residents, mid-level providers, fellows, attending surgeons and other members of the multi-disciplinary rounding team. We conducted a series of interviews with trainees regarding their user experience to assess the tool’s educational utility. Methods A convenience sample of residents who had recently completed their Burn Surgery rotation were interviewed in a structured format. Questions focused on the form’s ease of use and comprehensibility. Emphasis was placed on the extent to which it stimulates learning while rounding. Additional feedback was sought for the purpose of improving the tool for continued use. Results Participants were post-graduate year one or two resident physicians training in General Surgery, Urology, Emergency Medicine or Anesthesia. Prior experience and comfort with ICU level care ranged from very little to moderate. All interviewees found the tool helpful in their patient assessments, though the current layout of the form was a frustration for many. Overall, they unanimously found the forms beneficial for preparation of patient presentations and felt that utilization during rounds facilitated learning. Conclusions Interviews with trainees on their burn surgery rotation demonstrate that implementation of an ICU Rounding Tool has provided educational benefit, particularly for those less experienced in intensive care. Feedback from this cohort will be used to improve the tool’s usability. Our next steps will include a more formal survey of all trainees involved since the inception of this project.

Introduction Sepsis following critical burn injury is an ominous development that can lead to death. Most patients will manifest a systemic inflammatory response syndrome (SIRS), even without being septic. This may obscure the clinical recognition of developing sepsis and delay the initiation of effective treatment. We developed a burn sepsis screening tool (BSST) to facilitate the recognition of developing burn sepsis. The purpose of this study was to review the utility of that tool. Methods The BSST was based on several clinical signs, laboratory values, and changes in physiologic support modalities associated with sepsis. It consisted of nine parameters that could be scored as indicating or not indicating sepsis or not applicable. If three were positive, the patient was identified as septic, and a search for a septic source was undertaken and treatment initiated. The BSST was completed on patients judged to be critically ill during morning rounds over a period of nine months. The values were transcribed into a secure web database and analyzed using SAS 9.4. Results There were 593 individual encounters on 31 critically ill patients with burns and/or inhalation injury for which the BSST was completed. The mean age of the patients was 57 ± 4 years (Mean ± SEM), and the burn size was 24 ± 15 % TBSA. Eleven patients were women (36%) and 7 patients had inhalation injury (23%). The expected case fatality was 21 - 30% depending on the statistical model used. Six patients (19%) died. The length of stay was 64 ± 10 days and ranged from 3 to 267 days. A patient was judged to be septic in only 45 of the daily encounters (8.0 % ± 1.1). There were 21 instances of a new septic event made in 12 patients. Episode of sepsis separated by at least 5 days of no sepsis, were considered to be a new septic event. There was a substantial amount of data that was missing or not applicable. There were no significant differences in the septic parameters on days with new sepsis diagnosis when compared to the day prior, or compared to all encounters in patients that were never septic. Patients deteriorated acutely between BSST completions on only two occasions and both were stabilized. Conclusions The BSST was used consistently to help evaluate the daily status of critically ill burn injured patients. The expected case fatality of the group was moderately high, based on statistical models derived from the ABA Burn Registry. The observed outcome was as good as or better than predicted. Acute decompensation was rare. The BSST added daily administrative work to rounds, and the data recorded were often incomplete. Although the BSST did not demonstrate any single clinical feature that identified the transition from SIRS to sepsis, it did add structure and rigor to daily rounds. That contributed to the effectiveness of rounds, and it may have been responsible, in part, for the favorable outcomes.

Introduction Pediatric patients, between the age of newborn and 18 years, require legal guardian consent for any surgical procedure. In some cases, despite medical advisement, guardians refuse excision and skin graft for a minor in their care. In these cases, extended healing times, re-admission, scaring, contracture and physical disability may ensue. Our study aims to review contributing factors of guardian refusal and explore the outcomes of such refusals. Methods Retrospective chart review of all pediatric patients admitted to a large verified burn center between January 2018 through May 2019 were reviewed for total body surface area (TBSA) burned, age, depth of wound, mechanism, MD recommendation for surgical procedure, operative procedures conducted and length of hospital stay (LOS). Results Of the 265 pediatric patients admitted to the Burn Service, 32 (12%) were recommended surgical intervention during their hospitalization. Of these, 25 (78%) guardians consented for surgical skin grafting procedures following recommendation; 3 (9%) guardians delayed treatment consent by an average of 5 days; and 4 (13%) refused surgical consent for skin grafting procedures entirely. The average TBSA for patients recommended for surgical intervention was 8.7, those who accepted surgical intervention had an average TBSA of 8.35, compared to the 11.25 TBSA who refused surgical intervention. Average inpatient length of stay for patients whose guardians consented to surgical intervention promptly was 15.8 days. Despite an average 5 day delay in consent, guardians who deferred consent for surgical intervention doubled their length of stay (31.1 inpatient days). The four guardians who refused recommended surgical intervention had an average inpatient stay of 8.25 days. This finding is consistent with multi-day dressing use and outpatient clinic management. Of note, the four patients that did not receive surgical intervention for burn wound management were linked by common cultural background. Conclusions Pediatric burn injury is both acute and chronic, and the shock of initial injury is often overwhelming for both the patient and the guardian. Furthermore, guardians are then asked to make surgical decisions for a minor in their care. The burn team needs to have a heightened awareness of the cultural norms in the communities they serve to ensure quality care deliverance and patient safety. Applicability of Research to Practice Directly Applicable.

Passivating contacts are key enablers for high efficiency c-Si solar cells. Here, we present our latest advancement in terms of implementation and understanding in fired passivating contacts (FPC) used as rear p + passivating contact in p-type solar cells. We study three different layer configurations and show that the microstructural layer properties play a major role on the surface passivation and charge carrier transport. Upon optimization we demonstrate implied open circuit voltage of 722 mV corresponding to saturation current density of ~7 fA/cm2 and contact resistances below 10 mΩ cm2, when metallized with ITO/Ag. P-type c-Si solar cells employing a screen-printed P-diffused emitter co-fired with the FPC on the rear side with conversion efficiency up to 22.5% are demonstrated. Temperature-dependent measurements on test structures and solar cells reveal that tunneling is the main transport mechanism for FPC layers that crystallize during the firing process, whereas for more amorphous FPC layers, an additional component due to thermionic emission is also present. Finally, we present the efficiency potential of solar cells employing the developed FPC layer as hole selective rear side passivating contact.

The general electric propulsion orbit-raising maneuver of a spacecraft must contend with four main limiting factors: the longer time of flight, multiple eclipses prohibiting continuous thrusting, long exposure to radiation from the Van Allen belt and high power requirement of the electric engines. In order to optimize a low-thrust transfer with respect to these challenges, the choice of coordinates and corresponding equations of motion used to describe the kinematical and dynamical behavior of the satellite is of critical importance. This choice can potentially affect the numerical optimization process as well as limit the set of mission scenarios that can be investigated. To increase the ability to determine the feasible set of mission scenarios able to address the challenges of an all-electric orbit-raising, a set of equations free of any singularities is required to consider a completely arbitrary injection orbit. For this purpose we developed a new quaternion-based formulation of a spacecraft translational dynamics that is globally nonsingular. In this paper we consider the minimum-time low-thrust transfer of a GEO satellite and include the new set of equations of motion inside a direct optimization scheme implemented using an AMPL model and LOQO as NLP solver. Our goal here is to investigate the applicability of the new quaternion-based formulation to the low-thrust orbit-raising problem and compare the new methodology to previous approaches.

In this paper, we revisit the problem of electric orbit-raising of telecommunication satellites. The paper outlines the mathematical framework we have developed to determine trajectories that minimize the radiation damage during orbit-raising. This framework also allows us to analyze a variety of mission scenarios in order to identify the favourable designs for all-electric satellites. We outline the number and type of thrusters most suitable for the orbit-raising maneuver and the associated design of the power subsystem. We also consider the possible launch options of the satellites and demonstrate the advantages that all-electric satellites have by being stacked together to reduce the launch costs compared to their chemical or hybrid counterparts.

In this paper, we consider the development of an optimization solver that provides optimal low-thrust trajectories to the Geostationary Orbit, starting from an arbitrary orbit into which the satellite has been injected by an appropriate launch vehicle. Based on a direct optimization methodology, we formulate a minimum-time orbit-raising problem and use solvers like IPOPT and LOQO to solve the resulting non-linear programming problem. The tool allows for consideration of on-board energy storage system that helps the satellite to thrust in the Earth’s shadow during an eclipse. Furthermore, the tool allows for the investigation of new scenarios from the point of view of reducing radiation damage incurred by the satellite during its transit through the Van Allen belt. For instance, we consider the case in which the satellite starting from an inclined orbit, delays any out-of-plane maneuvers until it crosses the inner Van Allen belt. The tool enables us to analyze electric orbit-raising scenarios for a variety of injection orbits and different technology alternatives (electric engines, on-board energy storage). We illustrate with numerical examples the usage of the developed tool for different orbit-raising examples. The development of this solver is a first-step towards an elaborate study of new mission scenarios for all-electric telecommunication satellites.