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In the last years, the rapid emergence of photovoltaic technology has introduced a clean and renewable energy source, the significant potential of photovoltaic devices lies in their ability to transform light energy into electrical energy using cost-effective and eco-friendly methods. Organic materials have achieved notable increases in power conversion efficiency through chemical functionalization, proving advantages such as low-cost synthesis, high purity, and good charge transport properties in perovskites solar cells (PSCs). Challenges are still, including the stability and efficiency of organic materials, however, advances in material chemistry and structural optimization offer promising solutions that could significantly enhance the performance and commercial viability of PSCs. The integration of organic dyes for passivators, hole and electron transport layers in PSCs has shown improvements in device efficiency and stability, offering potential for increased efficiency and reduced production costs. [ABSTRACT FROM AUTHOR]

As demand grows for efficient and affordable photovoltaic technology, investigating alternative materials becomes crucial. Tin-based perovskite has a low bandgap, great optoelectronic properties, and higher carrier mobility. It has become an interesting absorber layer for perovskite solar cells (PSCs). However, improving their device performance presents challenges. Copper-based hole transport materials (HTM) and zinc-based electron transport materials (ETM) offer low cost, easy fabrication, and high electrical conductivity. This research analyzes the impacts of these transport materials on the FASnI 3 absorber layer using numerical modeling in SCAPS-1D. Through simulation analysis, the study thoroughly examines the effect of these materials on PSC performance parameters such as QE curve, layer thickness, defect density, interface defect, and doping concentration. Moreover, this study identifies the most efficient PSC configurations, achieving good performance by ITO/ZnSe/ FASnI 3 / Cu 2 O /Au with a V oc of 2.05 V, J sc of 29.316 mA/cm2, FF of 53.37 %, and power conversion efficiency (PCE) of 32.13 %, providing valuable insights in optimizing FASnI 3 solar cells and advancing next-generation solar energy conversion technologies. • SCAPS 1D simulation on perovskite solar cell. • Tin-based perovskite has emerged as encouraging absorber layer in perovskite solar cells. • Cu-based HTM and Zn-based ETM offer low cost, easy fabrication, and high electrical conductivity. • Using different HTL materials such as Cu 2 O , CuSbS 2 , and Zn-based ETL have been identified as potential candidates to enhance the performance of FASnI 3. • A study identifies good performance by ITO/ZnSe/ FASnI 3 / Cu 2 O /Au with a V oc of 2.05 V, J sc of 29.316 mA/cm2, FF of 53.37 %, and PCE of 32.13 %, [ABSTRACT FROM AUTHOR]

• DFT and TD-DFT modelling and extensive analysis of eight carbazole-based molecules as HTMs in perovskite solar cells. • Deep HOMO energy levels guarantee proper alignment with the perovskite material. • Acceptor core groups enhance charge transport properties. • Flatness is beneficial when the core consisted of two cycles, particularly for MP 2 P 2 M. • MP 2 P 2 M is distinguished by its superior charge transfer properties. This study mainly focuses on DFT and TD-DFT modelling and extensive analysis of eight carbazole-based molecules (MM, MPM, MP 2. 5 M, MP 2. 6 M, MP 3. 5 M, MPPM, MP 2 P 2 M, and MP 3 P 3 M) as Hole Transporting Materials in Perovskite Solar cells. These compounds have in common the arm N3,N3,N6,N6-tetrakis(4-methoxyphenyl)-9H-carbazole-3,6-diamine (M) characterized by its strong ability to carry holes, low cost, and good stability. The molecule MM presents two arms without acceptor core, while other compounds present two arms separated by different acceptor cores: phenyl, biphenyl, pyridine or bipyridine. All under-probe compounds were favored candidates for HTMs in perovskite solar cells due to their excellent HOMO delocalization, reduced hole reorganization energies, lower chemical reactivity, longer radiative lifetimes, and spontaneous solvation processes. Flatness proved beneficial when the core consisted of two cycles, particularly for MP 2 P 2 M. The results showed that the HOMO levels were primarily influenced by M fragments in most of the molecules, while the LUMO levels were distributed across both the carbazole units and the cores. All molecules exhibited a more stable LUMO compared to that of Spiro-OMETAD, with MP 2 P 2 M showing a notably stable level, resulting in a narrower gap. The study found that, except for MP 2 P 2 M, these materials did not interfere with the perovskite layer and effectively filled pores. The incorporation of acceptor core groups improved the conjugation backbone and electronic states, significantly enhancing charge transport properties, particularly in molecules with a double ring structure. Furthermore, adding a pyridine center greatly increased solubility, especially in MP 3 P 3 M, suggesting that acceptor core inclusion benefits the solubility of the investigated HTMs. The use of two rings core was shown to enhance light harvesting efficiency, boost photocurrent generation, and improve charge transfer performance, particularly in MP 2 P 2 M, which is distinguished by its superior flatness, solubility, and charge transfer properties. [ABSTRACT FROM AUTHOR]

• Five Phenothiazine-based hole transporting molecules were designed for efficient perovskite solar devices. • DFT calculations, structural geometrical analysis, and electronic properties were performed. • The molecules were found to be better hole-transporters for perovskite building blocks. • Improved VOC and power conversion efficiencies, indicating potential for future efficient PSCs devices. Perovskite solar cells are the emerging photovoltaics devices due to their high efficiency because of broad range light absorption and better charge carrier and separation properties. However, in the past few decades their material degradation and instability in the device operation accompanying low power conversion efficiency were the major drawbacks. To address these shortcomings, here we designed five Phenothiazine based novel hole-transporting molecules of d -Pi-A type with improved photovoltaic parameters for efficient perovskite solar devices. Detailed DFT calculation analysis with MPW1PW91 functions and 6–31 G basis set were performed for all molecules. Structural geometrical analysis along with density of states and transition density matrix analysis were extensively performed. Their electronic properties including HOMO and LUMO energies including energy gap, electron affinity, and ionization potential were also explored to elucidate the charge transfer characteristics. The lower values of reorganization in relation to reference molecules show that all designed molecules are better hole-transporters for perovskite building blocks. Lastly the devices photovoltaic parameter calculations for all the designed systems revealed that their Fill factor (FF), VOC and resultant power conversion efficiencies were significantly improved (18.63–22.81 % than its reference counterpart with PCE of 16.7 %) demonstrating their great potential for the future efficient PSCs devices. [ABSTRACT FROM AUTHOR]

The article analyses the research related to the issue of detecting anomalies in current medical data. The work aims to develop an information system for detecting data anomalies in the format of time series, such as metrics, with the ability to visualize the results for expert evaluation. The process of detecting anomalies by machine learning tools for detecting anomalies in the flow data is investigated. A system for detecting anomalies in metrics using the HTM model is built. According to the model results, obtained satisfactory accuracy for detecting anomalies at standard network parameters, the estimation of anomalies differed clearly for different aggregation intervals. The OPF Client functionality was used to build the HTM model, which allowed to achieve speed and simplicity in its construction. The obtained results allow the expert to choose the best of the size of the intervals as well as the parameters of the models. This choice is necessary because the presence of the anomaly depends on expert knowledge in a particular field. [ABSTRACT FROM AUTHOR]

In a vehicular environment, by becoming connected, vehicles are subject to more threats in comparison to traditional information systems, with the difference that, as a cyber-physical system, anomalies and intrusions could have repercussions in the physical world. In this work, we have developed an ontological anomaly-detection approach (OADA). The anomalies studied in this work mainly concern: network scans, DNS tunnel attacks, and telemetry data anomalies. Our contribution relates to a study of the attributes of interest for the algorithm used during the detection phase, namely the hierarchical temporal memory algorithm (HTM). The packets exchanged by the vehicle are grouped in instant description windows. These windows are then analyzed to extract a set of attributes. These are linked to the properties of network traffic, such as flow or latency. They are subject to the process of detecting anomalies and intrusions, carried out thanks to the algorithm with HTM. For each entry, the algorithm produces a score that allows us to decide if a window is abnormal and to lift an alert if that is the case. We evaluated our system using a communications and anomalies emulation tool. We use the corpus of data produced thanks to Autobot. We seek to determine from among the best scores of Matthews correlation coefficient (MCC) and Detection efficiency score (DES) which were the parameters for which HTM detects all anomalies with the greatest possible coverage. The obtained results prove that HTM can detect all anomalies for each window duration. [ABSTRACT FROM AUTHOR]

• A bio-inspired learning system for trajectory anomaly detection is proposed. • The method is tested on 2D object trajectories and 3D air signature verification. • An ELM-HTM fusion framework is used. Artificial intelligent systems often model the solutions of typical machine learning problems, inspired by biological processes, because of the biological system is faster and much adaptive than deep learning. The utility of bio-inspired learning methods lie in its ability to discover unknown patterns, and its less dependence on mathematical modeling or exhaustive training. In this paper, we propose a new bio-inspired learning model for a single-class classifier to detect abnormality in video object trajectories. The method uses a simple but dynamic extreme learning machine (ELM) and hierarchical temporal memory (HTM) together referred to as ELM-HTM in an unsupervised way to learn and classify time series patterns. The method has been tested on trajectory sequences in traffic surveillance to find abnormal behaviors such as high-speed, unusual stops, driving in wrong directions, loitering, etc. Experiments have also been performed with 3D air signatures captured using sensors and used for biometric authentication(forged/genuine). The results indicate a significant gain over training time and classification accuracy. The proposed method outperforms in predicting long-time patterns by observing small steps with an average accuracy gain of 15% as compared to the state-of-the-art HTM. The method has applications in detecting abnormal activities in videos by learning the movement patterns as well as in biometric authentication. [ABSTRACT FROM AUTHOR]

Recurrent Neural Networks such as Long Short-Term Memory (LSTM) and Gated Recurrent Units (GRUs) are often deployed as neural network-based predictors for time series data. Recently, Hierarchical Temporal Memory (HTM), a machine learning technology attempting to simulate the human brain's neocortex, has been proposed as another approach to time series data prediction. While HTM has gained a lot of attention, little is known about the actual performance compared to the more common RNNs. The only performance comparison between the two, performed at the company behind HTM, shows they perform similarly. In this article, we present a more in-depth performance comparison, involving more extensive hyperparameter tuning and evaluation on more scenarios. Surprisingly, our results show that both LSTM and GRUs can outperform HTM by over 30% at lower runtime. Furthermore, we show that HTM requires explicitly timestamped data to recognize daily and weekly patterns, while LSTM only needs the raw sequential data to predict such time series accurately. Finally, our experiments indicate that the temporally aware components of all considered predictors contribute nothing to the prediction accuracy. We further strengthen this claim by presenting equally or better performing Multilayer Perceptrons conceptually similar to the HTM and LSTM, disregarding their temporal aspects. [ABSTRACT FROM AUTHOR]

The strategy of ion doping in metal oxide is generally used to enhance the photoanode film feature, attain a suitable energy band and enhance carrier mobility. Here, a rare earth element erbium was doped into TiO 2 electron transport layer (ETL) by adding erbium trinitrate into the titanium precursor solution. In the present investigation, an attempt has been made to fabricate perovskite sensitized erbium doped TiO 2 nanoparticle (Er3+@TNPs) photoanode solar cell with different hole transport materials (HTMs) and graphite coated counter electrode. The perovskite sensitized solar cell (PSSC) built with CH 3 NH 3 SnI 3 sensitized Er3+@TNPs photoanode and spiro-MeOTAD HTM shows an impressive photovoltaic performance had the power conversion efficiency (PCE) of 11.54% when compared to the undoped TiO 2 photoanode PSSC. The results of this investigation indicate that the rare earth ion doping could be a promising method for producing effective ETL and enhanced performance PSSCs. • This work is mainly focused to increase the power conversion efficiency of photovoltaic devices using efficient photoanode structure, competence perovskite material with spiro-MeOTAD hole transport material. • The results showed in the present investigation, the device structure and the materials used in this study, significantly satisfied our focus of interest. [ABSTRACT FROM AUTHOR]

• Overview of CzDMPA based hole transporting materials (HTMs) for perovskite solar cells (PCSs) is discussed. • Classification of DMPA-containing carbazole based HTMs is given. • Research trends in synthetic pathways and structure-property relationship are reviewed. • Photovoltaic performance and stability in PCSs are summarized. Perovskite solar cells (PSC) based on metal-organic halide perovskites have emerged as one of the most promising photovoltaic technologies. Power conversion efficiency (PCE) has increased remarkably over the last few years from less than 10% up to certified efficiencies exceeding 23%. Selective interfacial layers play a critical role in charge extraction processes. In order to obtain high efficiencies, a hole transporting material (HTM) is required. Huge research efforts have been made to design efficient and low-cost materials. Carbazole-based HTMs are among the most promising new HTMs, in particular when they are substituted with dimethoxydiphenylamine (DMPA) units. This review gives an overview of the different classes of DMPA-containing carbazole-based HTMs and highlights the synthetic pathways, the structure-property relationship and the photovoltaic performances obtained in PSC devices. The relevance of structural variations and chemical doping processes is discussed with regard to efficiency and stability issues. [ABSTRACT FROM AUTHOR]

The impact of a significantly lower ferric (Fe3+) ion concentration on the structural, morphological, optical, and electrochemical properties of spin-coated Fe x Ni 1-x O thin films cast on Indium Tin Oxide (ITO) glasses was scrutinized and then compared with a higher ferric (Fe3+) ion concentration. After a careful structural study of the Fe x Ni 1-x O thin films by X-ray diffraction (XRD) analysis, the film surface was further analyzed by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) study, and X-ray photoelectron spectroscopy (XPS). Even for a noticeably small amount of substituted Ni2+ metal cations by Fe3+, degradation of the host crystal lattice was surprisingly higher. The influence of Fe3+ ions on the optical properties of Fe x Ni 1-x O ITO thin films was studied using UV–visible absorption spectra and Raman spectra. Both unsubstituted and Fe-substituted NiO ITO thin films showed photoluminescence properties. Changes in resistance values in pristine and Fe x Ni 1-x O thin films were monitored by an electrochemical impedance spectroscopy (EIS) study. Fe-substituted NiO thin films with a lower molar concentration showed better electrochemical performance as compared to those with a higher molar concentration of Fe3+ ions. This fact was further reinforced through a current-voltage (IV) study and a cyclic-voltagram (CV) study. [Display omitted] • Fe3+ substituted non-stoichiometric Fe x Ni 1-x O thin films using spin coating. • Minimum Fe3+ substitution in NiO triggering significant structural modification. • PL emission indicating metal defect formation during Fe3+ substitution. • Nickel vacancy defects inducing hole-driven conductivity upon minute Fe3+. [ABSTRACT FROM AUTHOR]

Abstract We aim to form stable representations of temporal sequences with key focus on semantic learning and streaming data. The state of the art in the Hierarchical Temporal Memory is represented by Numenta's recently published "ColumnPooler" which emulates functionality of cortical L2/3 layer, forms stable allocentric representations of temporal sequences and/or objects, and has been applied to sensory-motor learning. Our designed experiments evaluate the ColumnPooler for such task and uncover its current limitations. Presented "Motion Memory" design defines needed modifications in order to be effectively used for sequence representation, namely: Semantic distance between the representations; Online learning on streams; ability to represent time; and representation of motion from static sensor. One of the main problems with the current design is the lack of semantic meaning in (continuously updated) representations of the object. The proposed improvement enables MotionMemory to do unsupervised learning on streaming data and resulting representation have semantic meaning, this has many practical applications in sensory processing (ie. vision), or hierarchical learning. [ABSTRACT FROM AUTHOR]

In this study, six small carbazole-based molecules are investigated for usage as hole transport materials (HTMs) in perovskite solar cells. Among these compounds, two molecules based on 9-(4-(thiophen-2-yl)phenyl)-9H-carbazole thiophene-phenyle and carbazole (M 1 and M 2) were already synthesized, and four new molecules are designed by substituting carbazole, in positions 3,6 and 2,7, with methoxyphenyl (P 1 and P 2) and dimethoxyphenylamine (E 1 and E 2). Theoretical methods used in the calculations included density functional theory and time-dependent density functional theory. FMOs of all under-probe molecules are well positioned to ensure accurate alignment and prevent charge recombination at the perovskite material interface. The molecules' absorbance in the area below 404 nm shows that HTMs cannot compete with perovskite materials in an inverted configuration of a device. Reorganization energies indicate that M 1 , P 1,2 and E 1,2 are more favourable to be HTM, while M 2 shows a favourable electron transfer; it can be used as an electron transfer material (ETM). The results demonstrate that hole-electron couples can easily separate for any under-exanimated molecules, simplifying hole transport and enhancing the short-circuit (J SC). Additionally, DMPA-based molecules (E 1,2) may display chemical instability because of their poor hardness and the local distribution of charge in electrostatic potential maps. [ABSTRACT FROM AUTHOR]

We demonstrate for the first-time liquid exfoliated few layers of 2D Black phosphorus (BP) nanosheets as a hole transporting material (HTM) for perovskite based solar cells. The photoelectron spectroscopy in air (PESA) measurements confirm the low laying valence band level of BP nanosheets (−5.2 eV) favourable for hole injection from CH 3 NH 3 PbI 3 (MAPbI 3 ). Our results show that ∼25% improvement in power conversion efficiency (PCE) of η = 16.4% for BP nanosheets + Spiro-OMeTAD as an HTM as compared to spiro-OMeTAD (η = 13.1%). When BP nanosheets are exclusively utilised as an HTM, a PCE of η = 7.88% is noted, an improvement over the 4% PCE values observed for HTM free devices. Photoluminescence (PL) quenching of MAPbI 3 and impedance measurements further confirm the charge extraction ability of BP nanosheets. The structural and optical characterization of liquid exfoliated BP nanosheets is discussed in detail with the aid of transmission electron microscopy, Raman spectroscopy, absorption spectroscopy and photo-electron spectroscopy. [ABSTRACT FROM AUTHOR]

All-solid-state organic-inorganic halide perovskite solar cells (PSCs) have attracted wide attention due to the rapid progress of power conversion efficiency in recent years. Hole transport material (HTM) in PSCs plays the role of extracting and transporting photo-excited holes. Anisotropy of carrier mobility is one important property for semiconductors, however, which still remains unclear for the dominant HTM spiro-OMeTAD used in PSCs. Based on Density Functional Theory (DFT) and Marcus theory, we for the first time conducted investigations on the anisotropy of carrier mobility along representative crystal planes of spiro-OMeTAD by recombination energy λ and electronic coupling integral V . Results indicate that the holes and electrons show transport orientations consistency parallel to the (010), (101) and (111) crystal planes while inconsistency was found parallel to (100), (110), (011) and (001) crystal planes (with an angle ranged from 40° to 70° between the hole and electron transport directions). Our work embodies the theoretical significance of controllable and oriented fabrication of HTM in PSCs. [ABSTRACT FROM AUTHOR]

Quality of Experience (QoE) measurement in stereoscopic 3D is a challenging topic and existing standards such as ITU-R BT.500 may no longer be adequate for reliability and efficiency. Yet, objective measurement of QoE is not well researched for 3D images and videos. We present a new subjective assessment methodology providing better time-efficiency and more accurate scores at the same or even less number of assessors, using new objective metrics for QoE measurement of compressed multi-view video. Our research focus is twofold. First, the novel subjective testing methodology is developed, and QoE of different multi-view video compression technologies is evaluated. A time-efficient solution is proposed as a multiple stimuli plus simultaneous presentation extension of the conventional Double Stimulus Continuous Quality Scale (DSCQS) method. Second, objective quality metrics are proposed based on structural similarity and depth maps. Experiments are conducted on an auto-stereoscopic display while H.264/MPEG-4 Advanced Video Coding (AVC)- and High Efficiency Video Coding (HEVC)-based encoders are used for compression. The results demonstrate that the new methodology is superior to the DSCQS method in terms of both evaluation time and accuracy. Furthermore, high correlation is achieved with the new objective quality metrics. [ABSTRACT FROM AUTHOR]

Emerging development in perovskite sensitized solar cell have ushered in a transformative shift in the evolution of efficient and low-cost solar cell technologies. The improvement represents significant progress in the performance of sensitized solar cells since their breakthrough in 1991. Existing unexplored opportunities with these new developments depicts potential platform to achieve higher efficiency. Earlier development in solid state dye sensitized solar cells (DSSCs) has led to the incorporation of novel semiconductor nanocrystalline quantum dots (QDs) and perovskite as alternative sensitizer to improve device stability and enhance absorption coefficient. The attractiveness of perovskite CH3NH3PbI3 as sensitizer for solar cell incorporates its cost-effectiveness and light-harvesting capability which has shown consistent improvement in device performance in recent years. The incorporation of metal chalcogenides into solid-state dye sensitized solar cells showed significant improvement in power conversion efficiency (PCE) of 18.05%. With CH3NH3PbX3 (X=Cl, Br, or I) as an alternative to dye, device performance has shown to be promising although emerging challenges require a prioritized concern. In this review, recent exciting improvements in the performance of perovskite solar cells were discussed and the fundamental mechanisms incorporated into the structural evolution leading to PCE of 20.8%. In addition, prospects overriding present challenges were proposed for future work toward practical realization of highly- efficient solar cell upon optimization. [ABSTRACT FROM AUTHOR]

One of the main obstacles to perovskite solar cells (PSCs) entering the market is the doping-induced degradation of expensive hole transport materials (HTMs), which results in poor device stability. Although lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) and 4-tert-butylpyridine (4-tBp) as additives are commonly used in HTMs, they often lead to low device stability and reproducibility due to their hygroscopic and volatile nature. In this study, we incorporated the dilithium phthalocyanine (Li 2 Pc) molecule into the Spiro-OMeTAD precursor solution with Li-TFSI and 4-tBp to produce triple-cation PSCs with an n–i–p configuration operating with high efficiency and stability. The addition of the Li 2 Pc molecule not only improves the perovskite/Spiro-OMeTAD interface but also increases the π–π stacking in the thin-film phase according to the absorption and Raman results. Based on space-charge-limited current, photoluminescence, time-resolved photoluminescence and lifetime analysis measurements, charge transfer is improved with the Li 2 Pc molecule and charge recombination losses are reduced. As a result, the control device showed a power conversion efficiency (PCE) of 20.0% with J SC = 24.6 mA/cm2 and fill factor (FF) = 72.7%, whereas the Li 2 Pc-doped device exhibited an improved PCE of 20.6% with J SC = 25.0 mA/cm2 and FF = 73.6%. The addition of Li 2 Pc resulted in more stable and high-efficiency solar cells that maintained approximately 90% of the initial efficiency after 40 days. [Display omitted] • The addition of the Li 2 Pc molecule can increase the π–π stacking in the thin-film phase. • Li 2 Pc can effectively passivate the defects at the triple-cation perovskite/Spiro-OMeTAD interface. • The efficiency of triple-cation perovskite solar cell is increased from 20.0% to 20.6%. • The device with Li 2 Pc retained about 90% of the initial efficiency after 40 days compared to the control device. [ABSTRACT FROM AUTHOR]

This paper proposes a geometric error model for the three-axis machine tool using the homogeneous transformation matrix. An error-prediction model for the three-axis CNC machine tools is presented. This model takes the geometric errors into consideration, using the homogeneous coordinate transformation matrix(HTM) to analyze the geometric error model, which can change the tool's complex position and orientation changes in space into matrix calculations to make the model simpler and more intuitive. A simple method using the cubic polynomial functions to fit the geometric error components is proposed. Using this method, the high-order, non-linear spatial geometric problem can be transformed into algebraic equation. To large extent, the difficulty of calculation is reduced. The QC20 ball-bar is used to measure, analyze and separate all the geometric error components. A new kind of particle swarm algorithm based on the genetic algorithm is developed to solve the algebra equation. [ABSTRACT FROM AUTHOR]

Due to their uncommon electronic properties, carbon-based nanomaterials have led to extensive research efforts in the field of photovoltaic energy conversion in the last two decades. Initially exploiting carbon nanotubes, carbon-based solar cells have now largely taken benefit from graphene and its various forms to demonstrate significant improvements in almost all device functions including charge generation, charge collection, and charge transport. More recently, hybrid metalorganic halide perovskites became one of the most promising materials for third generation solar cells, with efficiencies now competing with thin film technologies. While several issues remain to be addressed regarding device operation and stability, the incorporation of carbon-based nanostructures was rapidly proposed, and significant advances have been achieved so far. In this work, we review the recent progresses made in the specific field of graphene-based perovskite solar cells. We especially emphasize the relevance of the approach applied to hole and electron transport media (HTM and ETM), electrodes, as well as approaches aiming at improving the stability of the device. Tandem architectures based on graphene interlayers will also be discussed, illustrating the broad potentialities of graphene materials in the development of the perovskite-based photovoltaic technology. [ABSTRACT FROM AUTHOR]

In this letter, we report on nanostructured NiO x with particle size ∼85 nm as an efficient hole transport material (HTM) for low temperature processed inverted planar perovskite solar cell (PSC) with power conversion efficiency of 15.64%. The homogenous NiO x HTM layer facilitated the growth of high quality CH 3 NH 3 PbI 3 absorber with large crystal grains and the resulting PSC showed stable photovoltaic performance under continuous illumination. [ABSTRACT FROM AUTHOR]

• Perovskite solar cells with device structure of FTO/TiO 2 /MAPbI 3 /GO + spiro-MeOTAD/Au has been developed. • GO + spiro-MeOTAD has been used as HTM. • PCE of 8.3% has been achieved using GO + spiro-MeOTAD as HTM. • The insertion of GO enhanced the stability of the perovskite solar cells. Herein, we reported the fabrication of perovskite solar cells (PSCs) with device architecture of FTO/TiO 2 /MAPbI 3 /GO + spiro-MeOTAD/Au. Graphene oxide (GO) was synthesized by Hummer's method which was further incorporated with spiro-MeOTAD to develop the stable PSCs. The fabricated PSCs device exhibited good efficiency of 8.3% using GO + spiro-MeOTAD/Au as hole-transport material (HTM) whereas control device (without GO) showed efficiency of 6.95%. PSCs device (with GO + spiro-MeOTAD) also exhibited good stability up to 168 h under controlled humidity (∼40–50%). [ABSTRACT FROM AUTHOR]

In this study, DFT calculations carried out using Carbazole-based HTMs substituted with dimethoxy phenylamine units (DMPA) in positions 2,3,6,7 and 9 are coupled with the experimental results drawn from the literature. The most important challenge for us is to establish a link between the optoelectronic and structural properties of molecules and their performance as HTMs. In this work, we find that the important structural effect is generated by the pyridinic nucleus. The substituents linked to the nitrogen atom of carbazole do not contribute to HOMO or LUMO in most of the studied HTMs. Hence, apart from the illustrated performances, parameters as the contribution of such substituents to being attached to the perovskite, or to the cohesion of the HTM's molecules contributing to the perovskite stability all prove decisive. The 2,7 substitution favors more stabilization of LUMOs when compared to 3,6 substitution, which leads to a narrow gap for 2,7 homologous. This makes these 2,7-substituted molecules good candidates as light absorbent in Organic Solar cells. The differences in the solar cell performances using these HTMs is mostly linked to the effect of these groups on their intermolecular interactions on one hand, and on the interfacial contact between HTMs and perovskite on the other hand. [ABSTRACT FROM AUTHOR]

Abstract: Transactional Memory (TM) is a promising paradigm for parallel programming. TM allows a thread to make a series of memory accesses as a single, atomic, transaction, while avoiding deadlocks, livelocks, and other problems commonly associated with lock-based programming. In this paper we explore Hardware support for TM (HTM). In particular, we explore how HTM can efficiently support transactions of nearly unlimited size. For this purpose we propose EcoTM, an economical unbounded HTM that improves the efficiency of conflict detection between very large transactions by activating conflict-detection logic only for potentially-conflicting locations: shared and speculatively modified. EcoTM detects the potentially-conflicting locations automatically, without any program annotations. We evaluate EcoTM performance by comparing it with ideal-lazy HTM, unbounded eager HTM with perfect signatures, and LogTM-SE. Our evaluations show that EcoTM has similar performance as the ideal-lazy HTM, 8.8% better than the eager- perfect HTM, and over 35.7% better than LogTM-SE, on the average. [Copyright &y& Elsevier]

Abstract: Recently, triphenylamine (TPA), 4,4′-bis(phenyl-m-tolylamino)biphenyl (TPD), 4,4′-bis(1-naphthylphenylamino)biphenyl (NPB) and their derivatives are widely used in the organic light-emitting diode (OLED) devices as a hole-transporting material (HTM) layer. We have optimized twenty different structures of HTM materials by using density functional theory (DFT), B3LYP/6-31G method. All these different structures contain mono-amine and diamine TPA derivatives. The energies of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) along with molecular orbitals for these HTMs are also determined. We have found that the central amine nitrogen atom and the phenyl ring, which is next to the central amine nitrogen atom, show significant contribution to the HOMO and LUMO, respectively. The sum of the calculated bond angles (α+β+γ) of the central amine nitrogen atom has been applied to describe the bonding and the energy difference for HOMO and LUMO in these TPA derivatives. Electronic structure calculations have been performed for these TPA derivatives. Again, the LCAO-MO patterns of HOMO and LUMO levels of these derivatives are used to investigate their electron density. A series of electron-transporting steps are predicted for these compounds employing these calculated results. [Copyright &y& Elsevier]

Abstract: Recently, triphenylamine (TPA) and its derivatives become widely used in the organic light emitting diode (OLED) devices as a hole transporting material (HTM). The calculated ionization potential (I p ) and reorganization energy for the hole transport (λ +) for a series of triphenylamine (TPA) derivatives are related to their Hammett parameters (σ and σ +) theoretically. In this study, the semiempirical AM1 method has been used to optimize thirty-three TPA derivatives. The electronic structures of these compounds in the neutral and the radical-cation states were obtained based on the optimized geometrical structure. The I p and λ + values were generated by means of the calculated heat of formation (or total energy) for both the neutral and the radical-cation states. In particular, the calculated I p ’s for these derivatives were consistent with experimental data. The substitution effect for the mono-substituted TPA derivatives is displayed in that the TPA derivatives with the electron-donating substituent have lower I p and those with electron-withdrawing substituent have higher I p , comparing to that of non-substituted TPA derivative. The substituent effect in di- and tri-substituted TPA derivatives is more pronounced than that of the mono-substituted TPA derivatives. According to the calculated results, the calculated I p shows an excellent agreement with the experimental oxidation potentials (E p/2) of these TPA derivatives. Furthermore, these calculated results can be employed to predict the electro-luminescence properties for new and improved HTM. [Copyright &y& Elsevier]

[Display omitted] • Synthesis of imidazole-based Hole transfer Materials. • Excellent solution processability and stability suitable for efficient OLED. • HOMO levels for favourable hole injection as well as superior hole mobility. • The IMzB displayed current efficiency of 91.13 cd A−1 and EQE of 21.11%. • Highest current efficiency by solution processed green phosphorescent OLEDs. Organic small molecules have played a significant role in the field of organic light-emitting diodes (OLEDs) technology. Improving the stability of OLEDs continues to be a major task in organic electronics. To overcome this issue, it is essential to enhance the carrier injection into the emissive layer for better charge balance. Though OLEDs are highly desirable for the solution process, enabling simple and cost-effectively manufacturing to fabricate large-area devices, the development of hole-transporting materials (HTMs) still a considerable challenge. Herein the IMzN (1-(4-methoxyphenyl)-2-(4-nitrophenyl)-4,5-diphenyl-1H-imidazole) and IMzB (4-(1-(4-methoxyphenyl)-4,5-diphenyl-1H-imidazol-2-yl)benzoic acid) with excellent solution processability and stability suitable for efficient OLED devices using a simple and efficient microwave-assisted synthetic procedure. Thermogravimetric analysis of IMzN and IMzB suggested that the material be thermally stable up to 320–345 °C. No glass transition has occurred as confirmed by DSC indicating the amorphous nature of the materials, which is well supported by XRD analysis. Materials acquire the appropriate HOMO levels for favorable hole injection as well as superior hole mobility. As a result, both HTMs show better device performance than the commercially used TAPC. The IMzB as HTL shows remarkable current efficiency of 91.13 cd A-1 and EQE of 21.11%. This is the highest current efficiency reported using solution-processed green phosphorescent OLEDs. Devices with IMzB as HTL also exhibit relatively better stability under continuous stress. [ABSTRACT FROM AUTHOR]