Microscopic Measurements of Electrical Potential in Hydrogenated Nanocrystalline Silicon Solar Cells: Preprint

We report on a direct measurement of electrical potential and field profiles across the n-i-p junction of hydrogenated nanocrystalline silicon (nc-Si:H) solar cells, using the nanometer-resolution potential imaging technique of scanning Kelvin probe force microscopy (SKPFM). It was observed that the electric field is nonuniform across the i layer. It is much higher in the p/i region than in the middle and the n/i region, illustrating that the i layer is actually slightly n-type. A measurement on a nc-Si:H cell with a higher oxygen impurity concentration shows that the nonuniformity of the electric field is much more pronounced than in samples having a lower O impurity, indicating that O is an electron donor in nc-Si:H materials. This nonuniform distribution of electric field implies a mixture of diffusion and drift of carrier transport in the nc-Si:H solar cells. The composition and structure of these nc-Si:H cells were further investigated by using secondary-ion mass spectrometry and Raman spectroscopy, respectively. The effects of impurity and structural properties on the electrical potential distribution and solar cell performance are discussed

High-yield cognitive behavioral techniques for psychosis delivered by case managers to their clients with persistent psychotic symptoms an exploratory trial

Case managers spend more time with clients with schizophrenia than any other professional group does in most clinical settings in the United States. Cognitive behavioral therapy (CBT) adapted for individuals with persistent psychotic symptoms, referred to as CBT-p, has proven to be a useful intervention when given by expert therapists in randomized clinical trials. It is currently unknown whether techniques derived from CBT-p could be safely and effectively delivered by case managers in community mental health agencies. Thirteen case managers at a community mental health center took part in a 5-day training course and had weekly supervision. In an open trial, 38 clients with schizophrenia had 12 meetings with their case managers during which high-yield cognitive behavioral techniques for psychosis (HYCBt-p) were used. The primary outcome measure was overall symptom burden as measured by the Comprehensive Psychopathological Rating Scale, which was independently administered at baseline and end of intervention. Secondary outcomes were dimensions of hallucinations and delusions, negative symptoms, depression, anxiety, social functioning, and self-rated recovery. Good and poor clinical outcomes were defined a priori as a 25% improvement or deterioration. t-Tests and Wilcoxon’s signed-ranks tests showed significant improvements in all primary and secondary outcomes by the end of the intervention except for delusions, social functioning, and self-rated recovery. Cohen’s d effect sizes were medium to large for overall symptoms (d = 1.60; 95% confidence interval [CI], ?2.29 to 5.07), depression (d = 1.12; 95% CI, ?0.35 to 1.73), and negative symptoms (d = 0.87; 95% CI, ?0.02 to 1.62). There was a weak effect on dimensions of hallucinations but not delusions. Twenty-three (60.5%) of 38 patients had a good clinical result. One (2.6%) of 38 patients had a poor clinical result. No patients dropped out. This exploratory trial provides evidence supportive of the safety and the benefits of case managers being trained to provide HYCBt-p to their clients with persistent psychosis. The benefits reported here are particularly pertinent to the domains of overall symptom burden, depression, and negative symptoms and implementation of recovery-focused services

Improved light trapping in microcrystalline silicon solar cells by plasmonic back reflector with broad angular scattering and low parasitic absorption

We show experimentally that the photocurrent of thin-film hydrogenated microcrystalline silicon (?c-Si:H) solar cells can be enhanced by 4.5?mA/cm2 with a plasmonic back reflector (BR). The light trapping performance is improved using plasmonic BR with broader angular scattering and lower parasitic absorption loss through tuning the size of silver nanoparticles. The ?c-Si:H solar cells deposited on the improved plasmonic BR demonstrate a high photocurrent of 26.3?mA/cm2 which is comparable to the state-of-the-art textured Ag/ZnO BR. The commonly observed deterioration of fill factor is avoided by using ?c-SiOx:H as the n-layer for solar cells deposited on plasmonic BR.Electrical Sustainable EnergyElectrical Engineering, Mathematics and Computer Scienc