A new analytical expression that directly relates the open‐circuit voltage (Voc) in perovskite solar cells (PSCs) to the quasi‐Fermi level splitting (QFLS), interface energy offsets, and nonradiative ...recombination losses has been derived. It is found that the QFLS of the active layer plays a dominant role in enhancing Voc of PSCs. The newly derived Voc is applied to two PSCs with the hole transport layer (HTL) of polybis(4‐phenyl)(2,4,6‐trimethylphenyl)amine, and poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) and found that the first PSC has a higher Voc, which agrees well with the experimental results. It is found that both PSCs exhibit saturation of Voc at the higher charge carrier generation rates and hence at higher light intensities. The lower Voc in PSC with P3HT as HTL is attributed to the stronger band bending and higher interfacial defects. In accordance with the results, a large quasi‐Fermi level splitting and a minimal interfacial energy offsets may be considered when selecting material for high Voc PSCs.
This study presents an analytical light intensity‐dependent open‐circuit voltage expression, which provides a theoretical underpinning for the experimental open‐circuit voltage saturation in perovskite solar cells. The derived open‐circuit voltage expression is a function of quasi‐Fermi level splitting, interfacial energy offsets, and nonradiative recombination losses, which help understand the material selection and design of perovskite solar cells.
Abstract
The power conversion efficiency (PCE) of a ternary organic solar cell (TOSC) with an active layer consisting of PBDB‐T‐2F and two non‐fullerene materials Y6 and SF(BR)
4
is simulated. ...Tungsten disulphide (WS
2
) is used as the hole transport layer (HTL) to reduce the contact resistance between the active layer and anode which enhances the internal quantum efficiency to 91.7%. It is found that the use of a highly absorbing non‐fullerene small molecule acceptor, SF(BR)
4
, enhances the absorption as well as improves the stability. Finally, the incorporation of the graded refractive index coating, in the form of moth‐eye shaped nanostructures, on the top of glass reduces the reflection losses and enhances the transmission coefficient from 0.88 to 0.94. Thus, the TOSC simulated here, of the structure moth‐eye‐AR/glass/ITO/WS
2
/PBDB‐T‐2F:Y6:SF(BR)
4
/PFN‐Br/Al, produces a PCE of 20.87%. The results presented in this paper are expected to provide useful guidance for fabricating highly efficient and stable hybrid bulk‐heterojunction solar cells.
The present study reports the preparation of nanocrystalline cellulose (NCC) with further reinforcement using succination and amination to observe the unexploited sorption efficiency of chromium from ...water bodies. The increased surface area-to-volume ratio of nanoparticles, quantum size effects, and the ability to tune surface properties through molecular modification make NCC ideal for metal remediation. Novel NCC was also characterized on the basis of XRD and AFM techniques and found to have enough potential for functionalization. Fourier transform infrared spectrometry of functionalized biomass highlights NCC interactions with succination and amination reactions, responsible for sorption phenomenon of chromium. Sorption studies (batch experiments) result into the standardization of optimum conditions for removal of Cr(III) and Cr(VI) as follows: biomass dosage (2.0 g), metal concentration (25 mg/l), contact time (40 min), and volume of the test solution (200 ml) at pH 6.5 and 2.5, respectively. The adsorption data were found to fit both the Freundlich and Langmuir isotherms. The sorption capacity of the regenerated biomass remained almost constant after five cycles of sorption process, suggesting that the lifetime was sufficient for continuous application and was further confirmed by means of TGA analysis. Artificial neural networks model was developed to predict the removal efficiency of Cr(III) and Cr(VI) ions from aqueous solution using functionalized NCC. Back-propagation and Levenberg–Marquardt techniques are used to train various neural network architectures and the accuracy of the obtained models using test data set. The optimal neural network architectures of this process contain 15 and 16 neurons for Cr(III) and Cr(VI) respectively, with minimum mean-squared error for training and cross validation as for Cr(III) 1. 6.46422 × 10
−6
and 0.001137496 and for Cr(VI) 1. 30386 × 10
−6
and 0.002227835, respectively.
A comprehensive study of the operating temperature (Tcr) of three nonfullerene (NF) acceptor‐based bulk heterojunction organic solar cells (BHJ OSCs), two conventional (OSC1 and OSC3) and one ...inverted (OSC2) structure, is presented. A quantitative analysis of the thermal power generated by photon absorption in transport layers and electrodes, thermalization of photoexcited charge carriers, tail‐state recombination, and resistive heating is conducted. For all three OSCs, the dependence of operating temperature Tcr on the voltage is simulated and it is found that OSC1 and OSC2 operate at about 320 K and OSC3 at 319 K. It is also found that the thermal power generated due to thermalization (PT) and absorption in other than the active layer (PAbsol) in OSC3 are smaller than those in both OSC1 and OSC2 but the thermal power generated due to the resistive heating (PR) is larger in OSC3 than in OSC1 and OSC2, leading to the net power absorbed in the active layer of OSC3 being higher than that in OSC1 and OSC2. Thus, although the operating temperature of all three cells remains in the range from 320 to 321 K, OSC3 shows a better photovoltaic performance.
A comprehensive study of the operating temperature of three NF acceptor‐based bulk heterojunction organic solar cells, two conventional and one inverted structure, is presented, together with a quantitative analysis of thermal power generation by photon absorption in transport layers and electrodes, thermalization, tail‐state recombination, and resistive heating.
Introduction: Despite automation, manual load lifting is unavoidable in occupations like Industry, healthcare, defence, etc. Ergonomics studies on manual lifting conducted across the globe explored ...few aspects of biomechanical and physiological responses. It was hypothesised that, ‘holistic ergonomics approach’ involving simultaneous recording of these responses under single study, would elucidate potential injury causing factors more effectively and results could be validated by applying meta-analysis technique of literature review. Aim: To identify the potential determinants of manual lifting by applying multivariate statistics to existing data and correlate the results with determinants as per literature review applying meta-Analysis. Materials and Methods: Clustering and principal component analysis tools of factor analysis was applied on the data obtained under the pilot study (n=11) undertaken by same authors previously on manual lifting that assessed 26 dependent parameters simultaneously for load magnitudes (10 kg, 20 kg), lifting heights (floor-knuckle, knuckle-shoulder and floorshoulder) and lifting frequencies (1lift.min-1, 4lifts.min-1). Further, extensive scoping literature review on determinants of manual load lifting was done applying text mining tool of meta-analysis technique on R software platform using 921 pubmed abstracts published between 1991 and 2018. Results: Salient findings of factor analysis corroborated with that of scoping literature review. Accordingly, dependent variable ‘Vertical Ground Reaction Force (VGRF)’ and independent variable ‘vertical height of lift’ changed most significantly during manual lifting, showing significant positive correlations. Newton’s third law of motion states that while bipedal standing/walking/running on floor, two forces (with three vector components) are acting upon a person: the force of gravity (downward force, equivalent to body weight) and the Ground Reaction Force (GRF, an equal upward force exerted by floor). However, while standing still at one place for lifting load, only the largest vector component of GRF, i.e., VGRF acts on the body (=‘body weight’+‘load magnitude’) through the vertical height of lift. Conclusion: It may be concluded that ‘vertical height of lift’ and VGRF are possible indicators of injury potential of manual lifting. However, studies on larger sample size and meta-analysis of relevant full papers instead of abstracts need to be done in future.
In this paper, a mathematical model and the relevant computer code are developed to quantify the extraction probability rate of charge carriers (EPRCC) in a perovskite solar cell of the structure: ...Glass/ITO/PEDOT: PSS/CH3NH3PbI3/PC60BM/Al to investigate the influence of interfaces and grain boundaries. It is found that, without passivation, the probability of an electron generated near the anode reaches to the cathode is only 35%, while by passivating the interfaces and grain boundaries, this probability increases to about 60% at maximum power point condition. Likewise, without passivation, the probability of a hole generated near the electron transport layer‐active layer interface reaches to the hole transport layer is only 15%, while by passivating the interfaces and grain boundaries, this probability increases to about 45% at maximum power point condition. The same calculation has been done at the short‐circuit current condition, and it is found that at the maximum power point condition, passivation works better for increasing the EPRCC than at the short circuit current condition. The authors have also investigated the influence of grain boundary sizes on the EPRCC, and the results show that the EPRCC is almost grain boundary size independent.
To simulate the extraction probability rate of charge carriers using the finite difference method, the active layer of a PSC is divided into N meshes. The electrons are generated and move from left to right and the holes are generated and move from right to left by gradually accumulating in each mesh and getting transported to the respective electrode.
BACKGROUNDDirect oral anticoagulants (DOACs) have been increasingly used as anticoagulation therapy in the postoperative period. However, their effectiveness in post-cardiac surgical atrial ...fibrillation is yet to be determined. METHODSWe conducted a meta-analysis, searching three international databases from 1 January 2003 to 26 January 2022 for studies reporting on DOACs in at least 10 adult patients (>18 yr of age) with post-cardiac surgical atrial fibrillation. The primary outcomes were major neurological events and bleeding; secondary outcomes were mortality, hospital and ICU length of stay, cost, and other complications from therapy. We included studies of any design, including RCTs, cohort studies with and without propensity score matching methods, and single-armed case series. RESULTSTwelve studies (8587 DOACs; 8315 warfarin) were included in this meta-analysis. The incidences of postoperative bleeding and major neurological events with DOACs were 7.3% (95% confidence interval CI: 3.4-14.7%) and 2.2% (95% CI: 0.9-4.9%), respectively. The incidence of major neurological events was lower in high-risk patients, including those with hypertension and higher CHA2DS2-VASc score, whereas patients with prior transient ischaemic attack or stroke had higher incidence of bleeding. Trial sequential analysis revealed that the cumulative Z-curve crossed the conventional boundary of benefit. Compared with warfarin, DOACs reduced the risk of bleeding (relative risk RR 0.74; 95% CI: 0.62-0.89; P=0.0011) and major neurological events (RR 0.63; 95% CI: 0.48-0.83; P=0.0012) but not mortality (RR 1.02; 95% CI: 0.77-1.35; P=0.090). CONCLUSIONSDOACs reduced bleeding and major neurological events in patients with post-cardiac surgical atrial fibrillation, appearing safer than warfarin in this context. However, which specific DOAC provides the most effective anticoagulation in this patient population needs further investigation. CLINICAL TRIAL REGISTRATIONPROSPERO CRD42021282777.
Catabolite repressor activator (Cra) is a member of the LacI family transcriptional regulator distributed across a wide range of bacteria and regulates the carbon metabolism and virulence gene ...expression. In numerous studies to crystallize the apo form of the LacI family transcription factor, the N-terminal domain (NTD), which functions as a DNA-binding domain, has been enigmatically missing from the final resolved structures. It was speculated that the NTD is disordered or unstable and gets cleaved during crystallization. Here, we have determined the crystal structure of Cra from Escherichia coli (EcCra). The structure revealed a well-defined electron density for the C-terminal domain (CTD). However, electron density was missing for the first 56 amino acids (NTD). Our data reveal for the first time that EcCra undergoes a spontaneous cleavage at the conserved Asn 50 (N50) site, which separates the N-terminal DNA binding domain from the C-terminal effector molecule binding domain. With the site-directed mutagenesis, we confirm the involvement of residue N50 in the spontaneous cleavage phenomenon. Furthermore, the Isothermal titration calorimetry (ITC) assay of the EcCra-NTD with DNA showed EcCra-NTD is in a functional conformation state and retains its DNA binding activity.
Thermal stability, closely associated with the operating temperature, is one of the desired properties for practical applications of organic solar cells (OSCs). In this paper, an OSC of the structure ...of ITO/PEDOT:PSS/P
HT:PCBM/ZnO/Ag was fabricated, and its current-voltage (
-
) characteristics and operating temperature were measured. The operating temperature of the same OSC was simulated using an analytical model, taking into consideration the heat transfer, charge carrier drift-diffusion and different thermal generation processes. The simulated results agreed well with the experimental ones. It was found that the thermalization of charge carriers above the band gap had the highest influence on the operating temperature of the OSCs. The energy off-set at the donor/acceptor interface in the bulk heterojunction (BHJ) was shown to have a negligible impact on the thermal stability of the OSCs. However, the energy off-sets at the electrode/charge-transporting layer and BHJ/charge-transporting layer interfaces had greater impacts on the operating temperature of OSCs at the short circuit current and maximum power point conditions. Our results revealed that a variation over the energy off-set range from 0.1 to 0.9 eV would induce an almost 10-time increase in the corresponding thermal power generation, e.g., from 0.001 to 0.01 W, in the cells operated at the short circuit current condition, contributing to about 16.7% of the total solar power absorbed in the OSC.
In this paper, characterisation of exciton generation is carried out in three bulk-heterojunction organic solar cells (BHJ OSCs)-OSC1: an inverted non-fullerene (NF) BHJ OSC; OSC2: a conventional NF ...BHJ OSC; and OSC3: a conventional fullerene BHJ OSC. It is found that the overlap of the regions of strong constructive interference of incident and reflected electric fields of electromagnetic waves and those of high photon absorption within the active layer depends on the active layer thickness. An optimal thickness of the active layer can thus be obtained at which this overlap is maximum. We have simulated the rates of total exciton generation and position dependent exciton generation within the active layer as a function of the thicknesses of all the layers in all three OSCs and optimised their structures. Based on our simulated results, the inverted NF BHJ OSC1 is found to have better short circuit current density which may lead to better photovoltaic performance than the other two. It is expected that the results of this paper may provide guidance in fabricating highly efficient and cost effective BHJ OSCs.
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