The independent and joint association of accelerometer-measured physical activity and sedentary time with dementia: a cohort study in the UK Biobank.

BACKGROUND: Research on the association of physical activity and sedentary time with dementia is accumulating, though elusive, and the interaction effects of the two remain unclear. We analysed the joint associations of accelerometer-measured physical activity and sedentary time with risk of incident dementia (all-cause dementia, Alzheimer's disease and vascular dementia). METHODS: A total of 90,320 individuals from the UK Biobank were included. Accelerometer-measured total volume of physical activity (TPA) and sedentary time were measured at baseline and dichotomised by median (low TPA [< 27 milli-gravity (milli-g)], high TPA [≥ 27 milli-g]; low sedentary time [< 10.7 h/day], high sedentary time [≥ 10.7 h/day]). Cox proportional hazards models were used to evaluate the joint associations with incident dementia on both additive and multiplicative scales. RESULTS: During a median follow-up of 6.9 years, 501 cases of all-cause dementia were identified. Higher TPA was associated with a lower risk of all-cause dementia, Alzheimer's disease and vascular dementia; the multivariate adjusted hazard ratios (HRs) (95% CI) per 10 milli-g increase were 0.63 (0.55-0.71), 0.74 (0.60-0.90) and 0.69 (0.51-0.93), respectively. Sedentary time was only found to be linked to all-cause dementia, and the HR for high sedentary time was 1.03 (1.01-1.06) compared with that for low sedentary time. No additive and multiplicative relationship of TPA and sedentary time to incident dementia was found (all P values > 0.05). CONCLUSION: Higher TPA level was related to a lower risk of incident dementia irrespective of sedentary time, which highlighted the implication of promoting physical activity participation to counteract the potential detrimental effect of sedentary time on dementia.

Construction of path analysis model on related factors of social isolation in older people.

BACKGROUND: With the gradual acceleration of population ageing, social isolation in older people has increasingly become a hot topic of social concern. The reduction of valid social participation will cause older people to weaken their sense of belonging to the community and social acquisition, negatively impacting on older people's quality of life. This study is aimed to explore the main related factors affecting the social isolation of older people, so as to provide a solid scientific basis for improving the health behaviour of older people in China. METHOD: A cross-sectional study was conducted among 2267 community residents over 60 years old from four cites in Jiangsu Province, China. Perceived social support scale, Geriatric Depression Scale, Connor-Davidson Resilience Scale, Comprehensive Ability of Older People Assessment Scale and other influencing factors scales were used to investigate the current situation. Social isolation was measured with the Lubben Social Network Scale. Demographic data were evaluated using descriptive statistical analyses and relationships among study variables were determined to use a path analysis. All data were analyzed using SPSS version 22 and AMOS version 26 using T-test, analysis of variance, logistic regression analyses, and path analysis method. The test level was set at alpha = 0.05, and the difference was statistically significant at P-value <0.05. RESULTS: The results of the model test analysis indicated that the hypothesised paths were supported by data from our samples and demonstrated significance on the path coefficients (P < 0.05). Related factors in the three dimensions of social risk, economic risk and cultural risk have an impact on the social isolation of older people in the community through direct and indirect pathways, and also indirectly through the partially mediated role of depression. Overall, our hypothesised model was retained, indicating empirical support and adequate model fit indices for the theoretical model. CONCLUSION: The findings demonstrated the predictive role of related factors of social isolation in older people. In the future, we should focus on developing interventions by uniting many forces such as society, family and older people themselves to reduce social isolation among this vulnerable population and improve the quality of life of older people and promote healthy ageing.

Stable and Highly Efficient Photocatalysis with Lead-Free Double-Perovskite of Cs2 AgBiBr6.

Composition engineering of halide perovskite allows the tunability of the band gap over a wide range so that photons can be effectively harvested, an aspect that is of critical importance for increasing the efficiency of photocatalysis under sunlight. However, the poor stability and the low photocatalytic activity of halide perovskites prevent use of these defect-tolerant materials in wide applications involving photocatalysis. Here, an alcohol-based photocatalytic system for dye degradation demonstrated high stability through the use of double perovskite of Cs2 AgBiBr6 . The reaction rate on Cs2 AgBiBr6 is comparable to that on CdS, a model inorganic semiconductor photocatalyst. The fact of fast reaction between free radicals and dye molecules indicates the unique catalytic properties of the Cs2 AgBiBr6 surface. Deposition of metal clusters onto Cs2 AgBiBr6 effectively enhances the photocatalytic activity. Although the stability (five consecutive photocatalytic cycles without obvious decrease of efficiency) requires further improvements, the results indicate the significant potential of Cs2 AgBiBr6 -based photocatalysis.

Ambient Air Condition for Room-Temperature Deposition of MAPbI3 Films in Highly Efficient Solar Cells.

The power conversion efficiency of perovskite solar cells has been boosted rapidly, it has so far exceeded that of commercial polycrystalline silicon solar cells. This has prompted great interest in large-scale production and deployment of perovskite solar cells. However, state-of-the-art perovskite solar cells are fabricated inside gloveboxes and further annealing at high temperatures (typically at >100 °C for 30 min) is needed. These two required conditions are not compatible with, either in the respect to high-throughput or thermal budget, a feasible industrial production process. By eliminating the two requirements, the deposition of perovskite films both at room temperature and under ambient air condition will make the scalable roll-to-roll fabrication scheme feasible. Here, the anti-solvent (chloroform) washing is introduced to the previously developed hydrochloride-assisted method and demonstrate that the room-temperature method can be carried out under ambient air condition for MAPbI3 film deposition. Through this new procedure, a power conversion efficiency as high as 17.72% is achieved for MAPbI3 planar devices fabricated under a relative humidity of 30% at room temperature. Further, it is revealed that the room-temperature process MAPbI3 films show a near monoexponential decay pathway with a long photoluminescence lifetime of >400 ns.

Transcriptome Analysis Reveals Multiple Hormones, Wounding and Sugar Signaling Pathways Mediate Adventitious Root Formation in Apple Rootstock.

Adventitious roots (AR) play an important role in the vegetative propagation of apple rootstocks. The potential role of hormone, wounding, and sugar signalling pathways in mediating AR formation has not been adequately explored and the whole co-expression network in AR formation has not been well established in apple. In order to identify the molecular mechanisms underlying AR formation in 'T337' apple rootstocks, transcriptomic changes that occur during four stages of AR formation (0, 3, 9 and 16 days) were analyzed using high-throughput sequencing. A total of 4294 differentially expressed genes were identified. Approximately 446 genes related to hormones, wounding, sugar signaling, root development, and cell cycle induction pathways were subsequently selected based on their potential to be involved in AR formation. RT-qPCR validation of 47 genes with known functions exhibited a strong positive correlation with the RNA-seq data. Interestingly, most of the candidate genes involved in AR formation that were identified by transcriptomic sequencing showed auxin-responsive expression patterns in an exogenous Indole-3-butyric acid (IBA)-treatment assay: Indicating that endogenous and exogenous auxin plays key roles in regulating AR formation via similar signalling pathways to some extent. In general, AR formation in apple rootstocks is a complex biological process which is mainly influenced by the auxin signaling pathway. In addition, multiple hormones-, wounding- and sugar-signaling pathways interact with the auxin signaling pathway and mediate AR formation in apple rootstocks.

Sensitization of ZnO single crystal electrodes with CdSe quantum dots.

CdSe quantum dots (QDs) were attached to single crystal ZnO(0001) and ZnO(1100) substrates using capping groups, 4-mercaptobenzoic acid, 2-mercaptoacetic acid, 3-mercaptopropionic acid, 8-mercaptooctanoic acid, and 11-mercaptoundecanoic acid, as bifunctional linker molecules. The spectral response and photosensitization yields of the adsorbed QDs were studied with photocurrent spectroscopy. Atomic force microscopy (AFM) was used to verify the surface structure of the ZnO crystals and to examine the coverage and arrangement of the QDs on the single crystal surface. The inner-sphere aqueous redox couple Sx(2-)/S(2-), often used as a regenerator for chalcogenide-based QDs, as well as outer-sphere redox couples such as ferrocene, were able to regenerate the photoexcited CdSe QDs and suppress their photocorrosion. Differences in the binding of the QDs to different ZnO crystal faces are also reported.

Improving BiVO4 photoanodes for solar water splitting through surface passivation.

BiVO4 has shown great potential as a semiconductor photoanode for solar water splitting. Significant improvements made during recent years allowed researchers to obtain a photocurrent density of up to 4.0 mA cm(-2) (AM1.5 sunlight illumination, 1.23 VRHE bias). For further improvements of the BiVO4 photoelectrodes, a deep understanding of the processes occurring at the BiVO4-H2O interface is crucial. Employing an electrochemical loading and removal process of NiOx, we show here that carrier recombination at this interface strongly affects the photocurrents. The removal of NiOx species by electrochemical treatment in a phosphate electrolyte leads to significantly increased photocurrents for BiVO4 photoelectrodes. At a bias of 1.23 VRHE, the Incident Photon-to-Current Efficiency (IPCE) at 450 nm reaches 43% for the passivated BiVO4 electrode under back side illumination. A model incorporating heterogeneity of NiOx centers on the BiVO4 surface (OER catalytic centers, recombination centers, and passivation centers) is proposed to explain this improved performance.

The Relationship between Occupational Fatigue and Well-Being: The Moderating Effect of Unhealthy Eating Behaviour.

Tech giants are large, well-known internet and technology companies. Employees of such companies are generally expected to work fast and for long periods of time, causing them to experience high occupational fatigue. The relationship between occupational fatigue and well-being is complex. Furthermore, in the context of the workplace, unhealthy eating behaviour may be used as a mechanism to cope with fatigue and stress. This study explored the relationship between occupational fatigue, well-being and unhealthy eating behaviour within this specific professional population. Study 1 used qualitative research methods, in which in-depth interviews were conducted with staff working at 13 tech giants in Shenzhen, China (N = 50). The findings revealed that work-related stress and occupational fatigue are common among employees working for tech giants. Additionally, factors such as unhealthy eating behaviour, workload, working hours and workplace interpersonal relationships were found to influence occupational well-being. Study 2 involved a cross-sessional survey of 237 employees of tech giants. The results indicated that occupational fatigue negatively impacts occupational well-being and that unhealthy eating behaviours play a moderating role between occupational fatigue and occupational well-being. These findings highlight the significance of adopting appropriate measures to improve the situation and cope with the effects of occupational fatigue by managing unhealthy eating behaviours.

Transcriptomic Insights into Molecular Response of Butter Lettuce to Different Light Wavelengths.

Lettuce is a widely consumed leafy vegetable; it became popular due to its enhanced nutritional content. Recently, lettuce is also regarded as one of the model plants for vegetable production in plant factories. Light and nutrients are essential environmental factors that affect lettuce growth and morphology. To evaluate the impact of light spectra on lettuce, butter lettuce was grown under the light wavelengths of 460, 525, and 660 nm, along with white light as the control. Plant morphology, physiology, nutritional content, and transcriptomic analyses were performed to study the light response mechanisms. The results showed that the leaf fresh weight and length/width were higher when grown at 460 nm and lower when grown at 525 nm compared to the control treatment. When exposed to 460 nm light, the sugar, crude fiber, mineral, and vitamin concentrations were favorably altered; however, these levels decreased when exposed to light with a wavelength of 525 nm. The transcriptomic analysis showed that co-factor and vitamin metabolism- and secondary metabolism-related genes were specifically induced by 460 nm light exposure. Furthermore, the pathway enrichment analysis found that flavonoid biosynthesis- and vitamin B6 metabolism-related genes were significantly upregulated in response to 460 nm light exposure. Additional experiments demonstrated that the vitamin B6 and B2 content was significantly higher in leaves exposed to 460 nm light than those grown under the other conditions. Our findings suggested that the addition of 460 nm light could improve lettuce's biomass and nutritional value and help us to further understand how the light spectrum can be tuned as needed for lettuce production.

Sequential bio-treatment of ammonia-rich wastewater from Chinese medicine residue utilization: Regulation of dissolved oxygen.

To effectively treat actual ammonia-rich Chinese medicine residue (CMR) resource utilization wastewater, we optimized an anaerobic-microaerobic two-stage expanded granular sludge bed (EGSB) and moving bed sequencing batch reactor (MBSBR) combined process. By controlling dissolved oxygen (DO) levels, impressive removal efficiencies were achieved. Microaeration, contrasting with anaerobic conditions, bolstered dehydrogenase activity, enhanced electron transfer, and enriched the functional microorganism community. The increased relative abundance of Synergistetes and Proteobacteria facilitated hydrolytic acidification and fostered nitrogen and phosphorus removal. Furthermore, we examined the impact of DO concentration in MBSBR on pollutant removal and microbial metabolic activity, pinpointing 2.5 mg/L as the optimal DO concentration for superior removal performance and energy conservation.

Enhancing simultaneous nitrogen and phosphorus availability through biochar addition during Chinese medicinal herbal residues composting: Synergism of microbes and humus.

The disposal of Chinese medicinal herbal residues (CMHRs) derived from Chinese medicine extraction poses a significant environmental challenge. Aerobic composting presents a sustainable treatment method, yet optimizing nutrient conversion remains a critical concern. This study investigated the effect and mechanism of biochar addition on nitrogen and phosphorus transformation to enhance the efficacy and quality of compost products. The findings reveal that incorporating biochar considerably enhanced the process of nutrient conversion. Specifically, biochar addition promoted the retention of bioavailable organic nitrogen and reduced nitrogen loss by 28.1 %. Meanwhile, adding biochar inhibited the conversion of available phosphorus to non-available phosphorus while enhancing its conversion to moderately available phosphorus, thereby preserving phosphorus availability post-composting. Furthermore, the inclusion of biochar altered microbial community structure and fostered organic matter retention and humus formation, ultimately affecting the modification of nitrogen and phosphorus forms. Structural equation modeling revealed that microbial community had a more pronounced impact on bioavailable organic nitrogen, while humic acid exerted a more significant effect on phosphorus availability. This research provides a viable approach and foundation for regulating the levels of nitrogen and phosphorus nutrients during composting, serving as a valuable reference for the development of sustainable utilization technologies pertaining to CMHRs.

l-thyroxine attenuates extracellular Hsp90α-induced vascular endothelial calcification in diabetes mellitus, as revealed by parallel metabolic profiles.

BACKGROUND AND AIMS: Diabetic atherosclerotic vascular disease is characterized by extensive vascular calcification. However, an elevated blood glucose level alone does not explain this pathogenesis. We investigated the metabolic markers underlying diabetic atherosclerosis and whether extracellular Hsp90α (eHsp90α) triggers vascular endothelial calcification in this particular metabolic environment. METHODS: A parallel human/animal model metabolomics approach was used. We analyzed 40 serum samples collected from 24 patients with atherosclerosis and from the STZ-induced ApoE-/- mouse model. A multivariate statistical analysis of the data was performed, and mouse aortic tissue was collected for the assessment of plaque formation. In vitro, the effects of eHsp90α on endothelial cell calcification were assessed by serum analysis, Western blotting and immunoelectron microscopy. RESULTS: Diabetic ApoE-/- mice showed more severe plaque lesions and calcification damage. Stearamide, oleamide, l-thyroxine, l-homocitrulline and l-citrulline are biomarkers of diabetic ASVD; l-thyroxine was downregulated in both groups, and the thyroid sensitivity index was correlated with serum Hsp90α concentration. In vitro studies showed that eHsp90α increased Runx2 expression in endothelial cells through the LRP1 receptor. l-thyroxine reduced the increase in Runx2 levels caused by eHsp90α and affected the distribution and expression of LRP1 through hydrogen bonding with glutamine at position 1054 in the extracellular segment of LRP1. CONCLUSIONS: This study provides a mechanistic link between characteristic serum metabolites and diabetic atherosclerosis and thus offers new insight into the role of extracellular Hsp90α in promoting vascular calcification.

An n-Si/n-Fe2O3 heterojunction tandem photoanode for solar water splitting.

Few metal oxide photoanodes are able to reduce protons to hydrogen because their conduction band minimum is located at too positive potentials. This can be remedied by biasing the photoanode with a photovoltaic cell placed behind the photoanode. The disadvantage of such a tandem device is the rather complicated structure. Here, we demonstrate a very simple monolithic heterojunction tandem photoanode based on n-Si and n-type α-Fe2O3. Detailed characterization of this system in a basic planar configuration reveals that the silicon generates a photovoltage of ∼0.3 V, and that the heterojunction functions as a D4 tandem device in which the absorption of two photons leads to one high-energy electron in the external circuit. No Fermi level pinning occurs at the Si/Fe2O3 interface, and the tandem photoanode is thermodynamically able to split water without the need for an external bias potential. This suggests that the n-Si/n-Fe2O3 heterojunction photoanode is a promising system for solar water splitting.

Literature review of the research on nursing students' professional self-concept.

OBJECTIVE: To understand the current situation and progress of nursing students' professional self-concept, this review aimed to perform a general analysis of research related to the connotation of professional self-concept, measurement tools, influencing factors, effects, and intervention experiments. METHODS: Three databases (Web of Science, PubMed, and CNKI) were searched for relevant articles. Research articles that met specific criteria were included, with identified articles initially screened by title and keyword. Then the abstracts were screened for relevance, and the full text was read for validation before inclusion. Descriptive analysis was performed with relevant findings from data retrieved from various sources. RESULTS: Finally, 54 articles that met the criteria were included, which organised the connotation of self-concept of nursing speciality, and introduced six measurement scales, such as Professional Self-Concept of Nurses Instrument and Nurse's Self-Concept Questionnaire. A total of 16 investigations on influencing factors were described, and the results showed that there were internal individual and external environmental factors. The professional self-concept was formed by analysing both factors. This paper described 17 effect surveys and found that professional self-concept had an important impact on students' mental health, academic performance, and professional values, and so on. Eight intervention experiments including attribution training and hierarchical teaching were evaluated. CONCLUSIONS: Research articles on the professional self-concept included in this review were rich. These articles clarified the basic connotation of the concept, developed relatively mature measurement tools, found many influencing factors and effects, and proposed effective intervention strategies. They were of great value for understanding the professional self-concept and could provide a reference for scholars to conduct relevant research and practice. It also presents research prospects in this field, aiming to inspire future research.

Evaluating the Risk of Social Isolation in Older People: AHP-Fuzzy Comprehensive Evaluation.

Background: Social isolation is a serious and pervasive health issue among older people, and it is difficult to identify and assess effectively. Based on a thorough and scientific evaluation index system, AHP-Fuzzy comprehensive evaluation could be a valuable technique. Objective: It is crucial to establish interventions that focus on risk factors for the prevention of social isolation in order to give a strong scientific foundation for enhancing older people's health habits. This can be achieved by using a fuzzy comprehensive evaluation method to assess the risk of social isolation in older people. Methods: A hundred community members over 60 from Nanjing were selected as the evaluation subjects in China. After the element layer was split into three categories of "social risk, economic risk, and cultural risk" using the analytic hierarchy process approach, a total of 22 assessment indicators were picked to develop a risk evaluation index system. Results: The risk level of social isolation belonging to the "low risk, relatively low risk, medium risk, relatively high risk, high risk" of membership degree are respectively "0.3392, 0.2632, 0.2257, 0.1069, 0.0650". Fuzzy comprehensive evaluation analysis showed that social relations (0.4934), monthly income (0.4654), health status (0.5960) were significant factors of social isolation risk in older people. The results showed that factors related to social risk had the most significant impact on social isolation. Conclusion: It is scientific and feasible to construct the risk evaluation index model of social isolation risk for the elderly by using AHP-Fuzzy comprehensive evaluation method. In preventing social isolation of older people in the future, we should pay attention to the impact of social and cultural factors on them, and provide practical intervention programs and references from the government, community, family.

Current situation and factors influencing elderly care in community day care centers: a cross-sectional study.

Background: The latest census data show that people over 60 years of age account for about 18.7% of the total population in China, and the aging of the population has become an irreversible trend in the 21st century. This study aimed to investigate the current status and factors influencing the care of the elderly in community day care centers in order to lay the foundation for the development of better services in community day care centers. Methods: This study was a cross-sectional survey using convenience sampling in Nanjing, China. The survey instrument was the Day care and Elderly Care Service Needs Questionnaire, which included the Ability of Daily Living Assessment (ADL), the Xiao Shuiyuan Social Support Rating Scale (SSRS) and the Day care Elderly Care Service Needs Survey Form, and a general information survey. Results: A total of 450 elderly people in day care centers were surveyed. The elderly had different levels of demand for day care services, especially regarding daily care. Correlation analyses indicated that age (r = 0.619), education level (r = 0.616), source of income (r = 0.582), caregiver (r = 0.557), satisfaction with care service (r = 0.603), and degree of ADL (r = 0.629) were correlated with the need for elderly day care services (all p < 0.05). The factors influencing the demand for day care services encompassed age, education level, income source, caregiver, satisfaction with service, and ADL (all p < 0.05). Conclusion: Elderly care services in community day care centers are mainly based on daily and spiritual comfort, and the needs of the elderly are influenced by many factors. Timely nursing care policies and measures that target these factors are needed to improve elderly care.

Anti-osteoporosis mechanism of resistance exercise in ovariectomized rats based on transcriptome analysis: a pilot study.

Postmenopausal osteoporosis is the main cause of fractures in women. Resistance exercise has a positive effect on bone mineral density in postmenopausal osteoporosis patients, but its mechanism is unclear. The purpose of this study was to explore the mechanism of resistance exercise in improving ovariectomized osteoporotic rats based on the transcriptome sequencing technique. Eighteen female Sprague-Dawley rats were randomly divided into the sham-operated group, the non-exercise group, and the resistance exercise group. The rat model of postmenopausal osteoporosis was established by bilateral ovariectomy. Ten weeks after the operation, the resistance exercise group received 2 weeks of adaptive training, and 12 weeks of resistance exercise began in the 13th week. The rats were trained 5 days per week, in 4 sets of 3 repetitions per day. After the intervention, all rats were sacrificed, and the body weight, bone mineral density, trabecular bone microarchitecture, and bone biomechanics were examined. At the same time, RNA-seq and enrichment analysis of gene ontology and Kyoto Encyclopedia of Genes and Genomes were performed on the left tibias, followed by Elisa and RT-qPCR verification. It had been found that resistance exercise can effectively counteract the weight gain of ovariectomized osteoporotic rats, and has a good effect on bone mineral density and trabecular bone microarchitecture. Enrichment analysis showed that regulation of gene expression and osteoclast differentiation is the most closely related biological process and signaling pathway shared by RE/Ovx and NE/Ovx groups. Our results revealed that resistance exercise can play a role in inhibiting osteoclast activation and preventing the enhancement of osteoclast bone resorption function in ovariectomized osteoporotic rats by inhibiting Fos/Fosb-regulated TRAP activation and relieving Calcr inhibition, which has important application value in preventing bone loss caused by estrogen deficiency.

Associations of blood biomarkers with arterial stiffness in patients with diabetes mellitus: A population-based study.

BACKGROUND: Arterial stiffness contributes to additional cardiovascular risks in diabetic patients by triggering the loss of vascular and myocardial compliance and promoting endothelial dysfunction. Thus, prevention of arterial stiffness is a public health priority, and the identification of potential biomarkers may provide benefits for early prevention. This study investigates the relationships between serum laboratory tests and pulse wave velocity (PWV) tests. We also investigated the associations between PWV and all-cause mortality. METHODS: We examined a panel of 33 blood biomarkers among diabetic populations in the Atherosclerosis Risk in Communities Study. The carotid-femoral (cfPWV) and femoral-ankle PWV (faPWV) were measured using an automated cardiovascular screening device. The aortic-femoral arterial stiffness gradient (afSG) was calculated as faPWV divided by cfPWV. Biomarker levels were log-transformed and correlated with PWV. Cox proportional hazard models were employed for survival analysis. RESULTS: Among 1079 diabetic patients, biomarkers including high-density lipoprotein cholesterol, glycated hemoglobin, high-sensitivity troponin T, cystatin C, creatinine, and albuminuria were significantly correlated with afSG (R = 0.078, -0.193, -0.155, -0.153, -0.116, and -0.137, respectively) and cfPWV (R = -0.068, 0.175, 0.128, 0.066, 0.202, and 0.062, respectively). Compared with the lowest tertile of afSG, the risk of all-cause mortality was lower in the highest tertile (hazard ratio 0.543; 95% confidence interval 0.328-0.900). CONCLUSION: Certain biomarkers related to blood glucose monitoring, myocardial injury, and renal function significantly correlated with PWV, suggesting that these putative risk factors are likely to be important atherosclerosis mechanisms in diabetic patients. AfSG may be an independent predictor of mortality among diabetic populations.

Controlling the electronic coupling between CdSe quantum dots and thiol capping ligands via pH and ligand selection.

Comparison of the UV-vis absorption spectra of CdSe quantum dots (QDs) capped with various mercaptocarboxylic acid capping ligands reveals that only 4-mercaptobenzoic acid (MBzA) capping ligands lower the apparent optical band gap. We propose that the delocalization of the excitons in the CdSe QDs is extended onto the ligands via electronic coupling to the π system of the 4-mercaptobenzoic acid molecules through the Cd-S bond. Furthermore, we demonstrate that the electronic coupling between the QDs and the (MBzA) thiol ligands is influenced by the strength of the Cd-S bond that can be changed by protonating the S atom.

Improving the photovoltaic performance for PbS QD thin film solar cells through interface engineering.

Interfaces exist between functional layers inside thin film optoelectronic devices, and it is very important to minimize the energy loss when electrons move across the interfaces to improve the photovoltaic performance. For PbS quantum dots (QDs) solar cells with the classical n-i-p device architecture, it is particularly challenging to tune the electron transfer process due to limited material choices for each functional layer. Here, we introduce materials to tune the electron transfer across the three interfaces inside the PbS-QD solar cell: (1) the interface between the ZnO electron transport layer and the n-type iodide capped PbS QD layer (PbS-I QD layer), (2) the interface between the n-type PbS-I layer and the p-type 1,2-ethanedithiol (EDT) treated PbS QD layer (PbS-EDT QD layer), (3) the interface between the PbS-EDT layer and the Au electrode. After passivating the ZnO layer through APTES treating; tuning the band alignment through varying the QD size of PbS -EDT QD layer and a carbazole layer to tune the hole transport process, a power conversion efficiency of 9.23% (Voc of 0.62 V) under simulated AM1.5 sunlight is demonstrated for PbS QD solar cells. Our results highlights the profound influence of interface engineering on the electron transfer inside the PbS QD solar cells, exemplified by its impact on the photovoltaic performance of PbS QD devices.