In this paper, the efficacy of wild natural dyes as the sensitizer was investigated for the fabrication of natural dye-sensitized solar cells (DSSCs). The natural pigments were extracted from Crocus ...sativus (Saffron), Allium cepa L (red onion), Malva sylvestris (Mallow), and Oregano (Origanum vulgare) using solvent extraction method. Based on the UV–vis results, the extracted solutions have been shown to contain anthocyanin or chlorophylls pigments, which are excellent pigments required for the charge-carriers generation in the energy harvesting process from the sunlight. The efficacy of all sensitizers has been evaluated using the cyclic voltammetry and current-voltage open circuit experiments of the fabricated DSSCs. The photovoltaic performance of DSSCs in terms of efficiency, current, voltage, and filling factors was performed under standard illumination of AM 1.5G having an irradiance of 100mWcm−2. The results showed that the photoelectric conversion efficiency of the fabricated DSSCs were nearly less than 2%, while the open-circuit voltage and short-circuit current density were from 0.43 to 0.55 V and 0.45–0.54 mAcm-2, respectively. The appropriate LUMO energy level and the band-gap of these extracted dyes would enable them to become efficient sensitizer for utilizing in fabricated DSSCs. Therefore, due to the existence of carbonyl and hydroxyl groups in dye's chemical structures, it enable them to bind to the TiO2layer, consequently, improve the electron transfer, and enhance the energy conversion efficiency of the fabricated DSSC.
●Dye extracted from natural native plants used as sensitizer for TiO2 based dye-sensitized solar cells (DSSCs).●The efficiency of fabricated natural-DSSC is comparable with the reference cell.●The potential of dye extraction from four native plants Crocus sativus (Saffron(, Allium cepa L (red onion), Malva sylvestris (Mallow), and Oregano (Origanum vulgare) was evaluated by effectiveness on the fabricated DSSCs.
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•Response surface methodology was conducted to obtain optimum extraction condition.•Maximum pigment extracted from low-cost wild plants using the microwave-assisted method.•The ...extracted pigments enhanced DSSCs efficiency due to increasing optical activity.•The efficiency of fabricated natural-DSSC is comparable with the reference cell.
The major proportion of dye-sensitized solar cells (DSSCs) fabrication cost is attributed to the pigments. In this study, to increase the performance/cost ratio of DSSCs, we used several wild regional plants of Persian Gulf zone for natural pigment production. At first, the optimum conditions for pigment extraction were obtained for all plants using response surface methodology. The results showed that increasing temperature, as well as extraction time, increased the pigment extraction efficiency while the pH of the solution did not exert a significant effect on the extraction process. Besides, the microwave-assisted method and pure ethanol have the highest extraction efficiency compared to ordinary solvent extraction and water as the extraction method and solvent, respectively. Moreover, all pigments were characterized using circular dichroism, dynamic light scattering, and zeta potential techniques. The results showed that the extracted pigments from Malva verticillata have the highest optical activity while all kinds of pigments tend to make aggregates 12 h after the extraction. Finally, the effectiveness of each pigment was evaluated as a sensitizer in natural DSSCs that fabricated using the doctor blade technique. Based on the photovoltaic results of the DSSCs sensitized with extracted pigments, the open circuit voltage and short circuit current ranged from 0.35 to 0.542 V and 0.802 to 1.702 mA, respectively. The Microwave-assisted Malva verticillata-DSSC owned the highest energy conversion efficiency of 1.702% as well as the comparable open circuit voltage to that of the reference DSSC that made using synthetic sensitizer. This superiority could be attributed to the highest pigments concentration as well as the highest pigments optical activity of Malva verticillata. Moreover, the results showed that the LUMO energy level and the band gap of the extracted pigments from Malva verticillata are better than the other natural pigments for DSSC fabrication. Besides, due to the presence of carbonyl and hydroxyl groups in chemical structures of extracted pigment from Malva verticillata, an effective bond between the pigment and TiO2 surface might be achieved and thereby increasing the energy conversion efficiency.
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•The co-sensitization approach employed to achieve panchromatic light-harvesting.•The treated cocktail with multi-anchor groups increased electron transfer channels.•Homogeneous ...dispersion of the pigment molecules improved dye adsorption efficiency.•The acidified cocktail enhanced the DSSC short current and efficiency.•Significant improvement in NDSSC stability was achieved using co-sensitization.
Co-sensitization is an effective strategy to achieve panchromatic light-harvesting and to enhance dye-sensitized solar cell performance. In this work, the potential of the extracted natural dyes from Malva verticillata and Syzygium cumini was evaluated as mono and co-sensitizers in DSSCs. The UV–vis absorption spectra revealed that the combination of studied dyes had a high molar extinction coefficient and cumulative absorption properties in a way that its absorption spectra overlapped the spectral domain where the original sensitizers lacked light-harvesting. Moreover, all investigated dyes were characterized using circular dichroism, dynamic light scattering, zeta potential, cyclic voltammetry, and Fourier-transform infrared spectroscopy. The results of zeta potential analysis showed that the pigment aggregation and their colloidal stability, which has implications for the pigment adsorption process on TiO2 nanoparticles, were effectively controlled by varying the pH of the dye extract. Based on the CV results, the studied dyes indicated excellent redox stability and sufficient thermodynamic driving force for efficient electron injection. Based on the photovoltaic results, the acidified cocktail-DSSC had the highest Isc and η of 3.15 mA and 1.84 %, respectively. This superiority could be ascribed to the panchromatic light-harvesting, the excellent optical activity, and the appropriate energy levels of the acidified cocktail. Moreover, the loading of acidified cocktail dyes on the TiO2 surface was enhanced due to their homogeneous dispersion, less steric hindrances, and multi-anchor groups attached to the semiconductor surface. Based on the stability results, the treated cocktail-DSSC retained about 52.51 % of its as-fabricated efficiency after seven days while NDSSCs sensitized with acidified Syzygium cumini, Malva verticillata, Syzygium cumini, and cocktail retained about 26.24 %, 14.80 %, 16.35 %, and 15.25 %, respectively.
Summary
The dye‐sensitized solar cells (DSSCs) can be effectively improved and stabilized by outstanding electrical and morphological characteristics of TiO2 nanofibres combined with bio‐calcium ...doping. The pristine and bio‐Ca‐doped TiO2 nanofibres were fabricated using a cost‐effective electrospinning technique. Biocompatible calcium carbonate nanoparticles (bio‐Ca) were synthesized from the cuttlebone of Sepia Pharaonis. Moreover, a facile one‐step procedure was employed to fabricate efficient TiO2 nanofibres‐based DSSCs using a Pechini‐type sol. This approach produced a highly porous dense film of TiO2 upon sintering without the need for the hot‐pressing or adhesion layer steps. Based on the results, the DSSCs fabricated by the bio‐Ca‐doped TiO2 nanofibres showed the highest Isc, Voc, and η of 2.19 mA, 0.41 V, and 1.48% respectively. This superiority could be due to the higher specific surface area and the relatively smaller average diameter observed for bio‐Ca‐doped TiO2 nanofibres, which improved dye‐loading and guided electron transport respectively. In addition, Ca2+ doping significantly suppressed the photocatalytic activity in the bio‐Ca‐doped TiO2 nanofibres owing to the formation of the TiO2 rutile‐anatase combined phase. Besides, the substitution of Ti4+ with Ca2+ positively affects the conduction band of TiO2 and causes trap sites that retard the charge recombination. Our results also demonstrated that the bio‐Ca‐doped TiO2 nanofibres‐based DSSC maintained about 78.38% of its initial efficiency after two weeks, while DSSCs fabricated by the TiO2 nanofibres and TiO2 nanoparticles retained 63.71% and 27.38% respectively. The superior stability could be due to the combined effect of nanoparticles into nanofibres transformation and bio‐Ca doping.
The dye‐sensitized solar cells (DSSCs) can be effectively improved and stabilized by outstanding electrical and morphological characteristics of TiO2 nanofibres combined with bio‐calcium doping. The pristine and bio‐Ca‐doped TiO2 nanofibres were fabricated using a cost‐effective electrospinning technique. Biocompatible calcium carbonate nanoparticles (bio‐Ca) were synthesized from the cuttlebone of Sepia Pharaonis.
Patients with confirmed COVID-19 infection can develop several psychological consequences. Epidemiological data on mental health and psychological disorder inpatients infected with COVID-19 pneumonia ...are not available in Iranian patients. The purpose of this study was to evaluate the anxiety, stress, and depression of patients with COVID-19.
This cross-sectional survey was conducted in 2020. All confirmed patients with COVID-19 were included in the study by census sampling. Assessment of depression, stress, and anxiety was performed using the DASS-21 questionnaire. All statistical analyses were performed using R version 3.5.1.
The questionnaires were completed by 221 patients with COVID-19 infection (204 males, 17 females). The mean age was 45.90 ± 7.73 years. Our results indicated that the mean scores of depression and anxiety were at "extremely severe" levels, while stress levels were "severe." The prevalence of "extremely severe" symptoms of depression and anxiety was 54.29% and 97.29%, respectively. The prevalence of severe stress was 46.61%.
In this study, patients infected with COVID-19 reported severe and extremely severe experience psychological distress. Further studies should focus on the combined use of psychological and molecular biomarker testing to increase accuracy. Overall, the findings demonstrate the necessity of special intervention programs for the confirmed patients with emerging infectious disease COVID-19 to promote mental health needs.
Aim The COVID-19 was declared a pandemic in early 2020 and is associated with high public anxiety all over the world. The healthcare community is at the highest risk of infection and thereby prone to ...most distress. The aim of this study was to explore and evaluate the degree of depression, anxiety, and stress levels among medical college students during the COVID-19 epidemic in Iran. Methods A cross-sectional study was conducted in February and March 2020, 3 weeks after the first reported COVID-19 infection was identified in Iran. All medical college students who entered clinical courses were eligible for the study. Depression, stress, and anxiety were evaluated in these students using the DASS-21 questionnaire. Participants were selected by using availability sampling. All statistical analyses were performed using R version 3.5.1. Results The total number of participants was 207, with 143 males and 64 females. More than half of the participants (57.97%) were married. The mean duration of working experience among students with COVID-19 infection and experience in a medical ward was 3.00 ± 1.27 days and 17.40 ± 7.26 months, respectively. The majority of students had 2 or 3 days working experience with COVID-19 infection. The mean anxiety score of participants was 28.56 ± 4.68, the depression score was 29.36 ± 4.42, and the stress score was 28.99 ± 4.53. Our findings indicated that the mean scores of depression were at an "extremely severe" level, while stress and anxiety were at "severe" levels. The prevalence of "severe" symptoms of depression, stress, and anxiety was 69.57%, 60.87%, and 99.04%, respectively. Conclusions There is a high prevalence of anxiety and depression among medical students who were exposed to COVID-19-infected patients. Our results highlight the need to establish psychological support programs, training, and self-care for medical college students in relation to mental health. We recommend incorporation of molecular biomarker tests into an algorithm to aid in assessments and consideration of the appropriate therapeutic responses.
Aim The ongoing COVID-19 outbreak has not only had an impact on physical health but also on psychological health. The aim of this study was to measure the prevalence and severity of psychological ...distress in the community due to the COVID-19 pandemic. Methods This cross-sectional survey was conducted in February and March 2020 in Tehran, Iran. We analyzed demographic characteristics and assessed depression, anxiety, and stress levels in 241 people using convenience sampling and the DASS-21 questionnaire. All statistical analyses were performed using R. Results The study population included 241 community-dwelling participants, of whom 145 were women and 96 were males. The mean age was 49.16 ± 8.01 years. Approximately two-thirds of participants (n = 158) reported no history of comorbid illness. The mean scores of depression and stress were at a "severe" level, while anxiety levels were at an "extremely severe" level. The prevalence of severe and extremely severe depression readings was 51.45 and 38.17%, respectively. In the anxiety subscale, the prevalence of severe and extremely severe depression was 95.90 and 4.1%, and in the stress subscale the prevalence was 48.97 and 4.98%, respectively. Conclusion In this study, people reported experiencing severe and extremely severe psychological distress. Therefore, there is an urgent need to implement mental health intervention policies to cope with this ongoing challenge. We suggest that the incorporation of molecular biomarker tests into the algorithm could aid in assessment of patients and guide the most appropriate therapeutic response.
The outbreak of COVID-19 has laid unprecedented psychological stress on healthcare workers (HCWs). We aimed to assess the immediate psychological impact of COVID-19 epidemic on the HCWs at ...Baqiyatallah Hospital in Tehran, Iran.
We conducted a cross-sectional survey of HCWs using questionnaires in February and March 2020 in Baqiyatallah Hospital, Tehran. We evaluated depression, stress, and anxiety levels using the DASS-21 questionnaire. Participants were selected by using census sampling. All statistical analyses were performed using R version 3.5.1.
The study population included 217 HCWs (111 male, 116 female) and the mean age of the study group was 39.6 years old. Approximately two-thirds of the HCWs stayed in the hospital for 2-3 weeks. The mean scores of depression and stress were at a "severe" level, while anxiety scores were at an "extremely severe" level. The prevalence of severe scores was 38.71%, 2.30%, and 48.97% for depression, anxiety, and stress, and the prevalence of extremely severe scores was 46.54%, 97.24%, and 4.98% depression, anxiety, and stress, respectively. In stress subscale, moderate stress was 47.46%. Female HCWs reported higher levels of depression compared with males.
In this study, HCWs reported experiencing severe and extremely severe psychological burdens. Timely interventions to promote mental health in HCWs exposed to patients with COVID-19 need to be immediately implemented, with female nurses requiring particular attention. This process could be facilitated via tests for molecular biomarkers in accessible body fluids, such as saliva, plasma, and serum.
