Leveraging off-stoichiometry to defeat n-type degeneracy in zinc tin nitride

Over the last decade, identification of new materials with potential applications to a wide variety of technologies has rapidly increased. In particular for solar technology, many new potential absorber materials based on earth-abundant and non-toxic elements have been predicted. These materials, often made in thin film form and known to absorb light 10–1000 times more efficiently than crystalline silicon, could lower photovoltaic (PV) module cost and enable broader solar deployment. One such material is zinc tin nitride (ZnSnN2), a II-IV-nitride analog of the III-nitride materials, which has been identified as a possible solar absorber due to its direct bandgap, large absorption coefficient, and disorder-driven bandgap tunability. Please click Additional Files below to see the full abstract

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Bridging the p-type transparent conductive materials gap: synthesis approaches for disperse valence band materials

Transparent conductive materials (TCMs) with high p-type conductivity and broadband transparency have remained elusive for years. Despite decades of research, no p-type material has yet been found to match the performance of n-type TCMs. If developed, the high-performance p-type TCMs would lead to significant advances in a wide range of technologies, including thin-film transistors, transparent electronics, flat screen displays, and photovoltaics. Recent insights from high-throughput computational screening have defined design principles for identifying candidate materials with low hole effective mass, also known as disperse valence band materials. Particularly, materials with mixed-anion chemistry and nonoxide materials have received attention as being promising next-generation p-type TCMs. However, experimental demonstrations of these compounds are scarce compared to the computational output. One reason for this gap is the experimental difficulty of safely and controllably sourcing elements, such as sulfur, phosphorous, and iodine for depositing these materials in thin-film form. Another important obstacle to experimental realization is air stability or stability with respect to formation of the competing oxide phases. We summarize experimental demonstrations of disperse valence band materials, including synthesis strategies and common experimental challenges. We end by outlining recommendations for synthesizing p-type TCMs still absent from the literature and highlight remaining experimental barriers to be overcome

Low Temperature p-type Microcrystalline Silicon as Carrier Selective Contact for Silicon Heterojunction Solar Cells

Silicon heterojunction (SHJ) solar cells have reached record efficiency, particularly in all-back-contacted architectures. Despite this, two-side contacted SHJ cells still suffer from parasitic absorption and series resistance losses in the amorphous silicon contacts. An alternative to the doped amorphous silicon layer is microcrystalline silicon, which exhibits improved transparency and charge transport while maintaining the superior passivation quality of all-silicon contact stacks. However, depositing thin, highly crystalline films has remained a challenge until recently. In this work, we use deposition temperatures <200 ◦C to improve the performance of p-type µc-Si:H contact layers. With these layers, we demonstrate Jsc gains of 1 mA/cm2, while reducing series resistance below 1 Ωcm2, leading to screenprinted 4 cm2 cells with certified η = 23:45%. Using a suite of device and material characterization techniques, we show that reduced deposition temperature leads to an increase in crystalline volume fraction from 35% to 55% for p-type films, which mitigates parasitic absorption in the front contact and facilitates hole extraction. These improvements are explained as resulting from higher transparency in the p-type layer accompanied by higher band bending in the c-Si wafer. These findings provide a method to improve SHJ solar cells performance, while offering insight into the importance of band bending considerations when optimizing heterojunction designs

Gallium Nitride as Transparent Electron-Selective Contact in Silicon Heterojunction Solar Cells

Carrier-selective, passivating contacts have allowed silicon heterojunction (SHJ) cells to reach recordbreaking efficiencies particularly in all-back-contacted designs. However, two-side-contacted SHJ cell efficiency has been limited due in part to parasitic absorption losses up to 3 mA/cm2 in the aSi:H layers. More transparent materials could reduce this current loss while minimizing process complexity. Gallium nitride (GaN), with a bandgap of 3.4 eV and an advantageous band alignment with silicon, could be applied as a transparent electron-selective layer. Here, we report on SHJ solar cells utilizing PECVD GaN layers grown at 200°C as electron-selective contact. First devices exhibited open-circuit voltages of ~575 mV due to poor passivation, and low conductivity of the as-yet undoped GaN layers induced high series resistance (Rs). However, this Voc suggests the potential for electron selectivity if appropriate passivation and doping strategies are implemented