Simultaneous passivation of the defects at the surface and grain boundaries of perovskite films is crucial to achieve efficient and stable perovskite solar cells (PSCs). It is highly desirable to ...accomplish the above passivation through rational engineering of hole transport materials (HTMs) in combination with appropriate procedure optimization. Here, methylthiotriphenylamine‐substituted copper phthalocyanine (SMe‐TPA‐CuPc) is reported as a dopant‐free HTM for PSCs, exhibiting excellent efficiency, and stability. After thermal annealing, SMe‐TPA‐CuPc molecules diffused into the bulk of the perovskite film and effectively passivated the defects in the bulk and at the interface of the perovskite, owing to the strong interaction between the methylthio moiety and undercoordinated lead. The best‐performing annealed SMe‐TPA‐CuPc‐based device shows efficiency of 21.51%, which is higher than the unannealed SMe‐TPA‐CuPc‐based device (power‐conversion efficiency (PCE) of 20.75%) and reference doped spiro‐OMeTAD‐based device (PCE of 20.61%). Further modification of the perovskite of the annealed SMe‐TPA‐CuPc‐based device by the QAPyBF4 additive result in even higher efficiency of 23.0%. It also shows excellent stability, maintaining 96% of its initial efficiency after 3624 h aging at 85 °C. This work highlights the great potential of phthalocyanine‐based dopant‐free HTMs and the defect passivation by thermal‐induced molecular diffusion strategy for developing highly efficient and stable PSCs.
Methylthiotriphenylamine‐substituted copper phthalocyanine (SMe‐TPA‐CuPc) is synthesized and used as dopant‐free HTM for perovskite solar cells. Owing to the strong interaction between the ‐SMe and undercoordinated lead, SMe‐TPA‐CuPc molecules could diffuse into the perovskite film after thermal annealing and effectively passivate the defects in the bulk and at the interface, which led to high efficiency and thermally stable devices.
Perovskite solar cells (PSCs) have grabbed much attention of researchers owing to their quick rise in power conversion efficiency (PCE). However, long‐term stability remains a hurdle in ...commercialization, partly due to the inclusion of necessary hygroscopic dopants in hole transporting materials, enhancing the complexity and total cost. Generally, the efforts in designing dopant‐free hole transporting materials (HTMs) are devoted toward small molecule and polymeric HTMs, where small molecule based HTMs (SM‐HTMs) are dominant due to their reproducibility, facile synthesis, and low cost. Still, the state‐of‐art dopant‐free SM‐HTM has not been achieved yet, mainly because of the knowledge gap between device engineering and molecular designs. From a molecular engineering perspective, this article reviews dopant‐free SM‐HTMs for PSCs, outlining analyses of chemical structures with promising properties toward achieving effective, low‐cost, and scalable materials for devices with higher stability. Finally, an outlook of dopant‐free SM‐HTMs toward commercial application and insight into the development of long‐term stability PSCs devices is provided.
It is requisite to develop dopant‐free hole transporting materials (HTMs) to avoid formidable engineering and instability in perovskite solar cells. Organic HTMs, especially small molecules are easily reproducible. While considering the stability and efficiencies of perovskite solar cells, this review reveals the role of different molecular design strategies applied to small molecule HTMs.
Defects and energy offsets at the bulk and heterojunction interfaces of perovskite are detrimental to the efficiency and stability of perovskite solar cells (PSCs). Herein, we designed an amphiphilic ...π‐conjugated ionic compound (QAPyBF4), implementing simultaneous defects passivation and interface energy level alignments. The p‐type conjugated cations passivated the surface trap states and optimized energy alignment at the perovskite/hole transport layer. The highly electronegative BF4− enriched at the SnO2 interface featured desired band alignment due to the dipole moment of this interlayer. The planar n‐i‐p PSC had an efficiency of 23.1 % with Voc of 1.2 V. Notably, the synergy effect elevated the intrinsic endothermic decomposition temperature of the perovskite. The modified devices showed excellent long‐term thermal (85 °C) and operational stability at the maximum power point for 1000 h at 45 °C under continuous one‐sun illumination with no appreciable efficiency loss.
A π‐conjugated ionic multifunctional additive (QAPyBF4) was developed and introduced into perovskite solar cells (PSCs). QAPyBF4 passivated defect states in the perovskite layer, adjusted energy level alignment at the perovskite/ETL and perovskite/HTL interfaces, and prevented the decomposition of perovskite crystals. Therefore, a planar PSC with QAPyBF4 delivered an efficiency of 23.1 % with a remarkable Voc of 1.2 V and operational stability.
Neuromorphic computing systems that are capable of parallel information storage and processing with high area and energy efficiencies, offer important opportunities for future storage systems and ...in‐memory computing. Here, it is shown that a carbon dots/silk protein (CDs/silk) blend can be used as a light‐tunable charge trapping medium to fabricate an electro‐photoactive transistor synapse. The synaptic device can be optically operated in volatile or nonvolatile modes, ensuring concomitant short‐term and long‐term neuroplasticity. The synaptic‐like behaviors are attributed to the photogating effect induced by trapped photogenerated electrons in the hybrid CDs/silk film which is confirmed with atomic force microscopy based electrical techniques. In addition, system‐level pattern recognition capability of the synaptic device is evaluated by a single‐layer perceptron model. The remote optical operation of neuromorphic architecture provides promising building blocks to complete bioinspired photonic computing paradigms.
An optoelectronic synaptic transistor based on a hybrid light‐tunable charge trapping medium is demonstrated. Optical programming and electrical erasing memory characteristics, along with volatile and nonvolatile memory are features of the synaptic device, enabling the mimicking of a range of neuroplasticity behaviors, including short‐term plasticity and long‐term potentiation.
A power conversion efficiency (PCE) as high as 19.7% is achieved using a novel, low‐cost, dopant‐free hole transport material (HTM) in mixed‐ion solution‐processed perovskite solar cells (PSCs). ...Following a rational molecular design strategy, arylamine‐substituted copper(II) phthalocyanine (CuPc) derivatives are selected as HTMs, reaching the highest PCE ever reported for PSCs employing dopant‐free HTMs. The intrinsic thermal and chemical properties of dopant‐free CuPcs result in PSCs with a long‐term stability outperforming that of the benchmark doped 2,2′,7,7′‐Tetrakis‐(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐Spirobifluorene (Spiro‐OMeTAD)‐based devices. The combination of molecular modeling, synthesis, and full experimental characterization sheds light on the nanostructure and molecular aggregation of arylamine‐substituted CuPc compounds, providing a link between molecular structure and device properties. These results reveal the potential of engineering CuPc derivatives as dopant‐free HTMs to fabricate cost‐effective and highly efficient PSCs with long‐term stability, and pave the way to their commercial‐scale manufacturing. More generally, this case demonstrates how an integrated approach based on rational design and computational modeling can guide and anticipate the synthesis of new classes of materials to achieve specific functions in complex device structures.
Highly‐efficient, low‐cost, solution‐processed perovskite solar cells, exhibiting remarkable environmental stability, are reported. The fabrication strategy relies on the rational design of the molecular structure of arylamine‐substituted copper(II) phthalocyanine (CuPc) derivatives, which are used as dopant‐free hole‐transport materials. The resulting devices reach a power conversion efficiency of 19.7% and display enhanced long‐term stability with respect to standard (doped) materials.
Fingertip skin exhibits high sensitivity in a broad pressure range, and can detect diverse stimuli, including textures, temperature, humidity, etc. Despite adopting diverse microstructures and ...functional materials, achieving skin sensor devices possessing high pressure sensitivity over a wide linear range and with multifunctional sensing capabilities is still challenging. Herein, inspired by the microstructures of fingertip skin, a highly sensitive skin sensor is demonstrated with a linear response over a broad pressure range and multifunctional sensing capabilities. The porous sensing layer is designed with hierarchical microstructures on the surface. By optimizing the porosity and the graphite concentration, a fabricated skin sensor device exhibits a superior sensitivity of 245 kPa−1 over a broad linear pressure range from 5 Pa to 120 kPa. For practical application demonstrations, the sensor devices are utilized to monitor subtle wrist pulse and diverse human motions including finger bending, wrist bending, and feet movement. Furthermore, this novel sensor device demonstrates potential applications in recognizing textures and detecting environmental temperatures, thereby marking an important progress for constructing advanced electronic skin.
Fingertip‐skin‐inspired skin sensors based on hierarchically structured conductive graphite/polydimethylsiloxane foams show high sensitivity in a wide pressure range. Furthermore, aside from sensing pressure, the skin sensors can distinguish the texture and temperature. Applications in monitoring physiological signals, distinguishing papers with different texture roughness, and indicating environmental temperatures are demonstrated.
Semiconducting molecules have been employed to passivate traps extant in the perovskite film for enhancement of perovskite solar cells (PSCs) efficiency and stability. A molecular design strategy to ...passivate the defects both on the surface and interior of the CH3NH3PbI3 perovskite layer, using two phthalocyanine (Pc) molecules (NP‐SC6‐ZnPc and NP‐SC6‐TiOPc) is demonstrated. The presence of lone electron pairs on S, N, and O atoms of the Pc molecular structures provides the opportunity for Lewis acid–base interactions with under‐coordinated Pb2+ sites, leading to efficient defect passivation of the perovskite layer. The tendency of both NP‐SC6‐ZnPc and NP‐SC6‐TiOPc to relax on the PbI2 terminated surface of the perovskite layer is also studied using density functional theory (DFT) calculations. The morphology of the perovskite layer is improved due to employing the Pc passivation strategy, resulting in high‐quality thin films with a dense and compact structure and lower surface roughness. Using NP‐SC6‐ZnPc and NP‐SC6‐TiOPc as passivating agents, it is observed considerably enhanced power conversion efficiencies (PCEs), from 17.67% for the PSCs based on the pristine perovskite film to 19.39% for NP‐SC6‐TiOPc passivated devices. Moreover, PSCs fabricated based on the Pc passivation method present a remarkable stability under conditions of high moisture and temperature levels.
Utilizing NP‐SC6‐TiOPc and NP‐SC6‐ZnPc as passivating agents on perovskite thin film through an antisolvent, improved performance and stability are achieved for perovskite solar cells. The highest power conversion efficiencies (PCEs) of 19.39% and 18.04% are obtained for NP‐SC6‐TiOPc and NP‐SC6‐ZnPc passivated devices, which is higher than that of the control devices without post‐treating the MAPbI3 films (PCE of 17.67%).
Abstract
Clamping force is crucial for resisting slip loads in friction-type high-strength bolted (FHSB) connections, and following corrosion, it diminishes due to sectional reduction of the nuts ...and/or bolt heads. Evaluating clamping force loss (CFL) in corroded FHSBs is essential for steel bridge inspection and maintenance. The cutting methods currently employed to simulate corrosion encounter challenges including limited shapes, low efficiency, and poor accuracy, leading to significant data dispersion in experiments and diminished reliability of evaluation models. Furthermore, existing evaluation models fail to fully consider the influence of factors such as corrosion shape, size, thread specifications, corrosion location, and initial clamping force (ICF) on clamping force. Hence, this research proposed a novel wire-cutting simulation corrosion method (WCSCM) and conducted experiments on 80 specimens. Based on experimental results, five clamping force evaluation models were systematically established for corrosion shapes including thickness uniform corrosion, height uniform corrosion, height and thickness corrosion, eccentric corrosion, and trapezoid corrosion, and their fitting accuracy was compared and analyzed. Furthermore, the impact of thread specifications, corrosion location, and ICF on clamping force was discussed. Finally, procedures for measuring field corrosion bolt dimensions and methods for approximating corrosion shapes were proposed, followed by validation of the evaluation model’s effectiveness through on-site bridge testing. The findings showed that the WCSCM accurately reproduced the corrosion shapes and sizes of the nuts and/or bolt heads, with regression equation coefficients exceeding 0.97, notably higher than those of existing models. The CFL resulting from various corrosion shapes and sizes exhibited variation, indicating the necessity for distinct models tailored to each corrosion damage pattern of the nuts and/or bolt heads. The impact of thickness uniform corrosion on clamping force primarily correlated with ICF, with less influence from thread specification or corrosion location. The proposed models were able to achieve an accuracy level within ±20%, providing a basis for replacing corroded bolts on steel bridges.
PtII complexes have attracted a great deal of interest due to their rich phosphorescent properties. However, these square‐planar PtII complexes are far more likely to encounter the problems of lack ...of metal‐induced chirality and emission “aggregation‐caused quenching”. Herein, soft‐bridged binuclear PtII complexes bearing metal‐induced planar chirality were synthesized and characterized. These soft bridging ligands with smaller conjugated system would help to not only improve solubility for synthesis and enantioseparation but also introduce point chirality from amino acid for highly efficient diastereoselectivity. Furthermore, the intramolecular Pt−Pt distances could be well regulated by soft bridging ligands, and consequently the phosphorescence quantum yield up to 100 % could be achieved by shortening intramolecular Pt−Pt distance for first time. These complexes can be used as emitters in highly efficient solution‐processed organic light‐emitting diodes.
Racemic (R)/(S) and enantiopure (D,R,D)/(L,S,L) binuclear PtII complexes with metal‐induced planar chirality were designed and prepared by using soft‐bridged achiral and chiral ligands, respectively. Their phosphorescence quantum yields up to 100 % can be achieved by shortening intramolecular Pt−Pt distance for highly efficient solution‐processed circularly polarized OLEDs.
Abstract
33.7% of power conversion efficiency (PCE) in monolithic perovskite‐silicon tandem solar cells (PSTSCs) is an eye‐catcher. Still, the issues emerging from their two main requirements, wide ...band gap (WBG) perovskites and textured substrates, trigger phase segregation, voltage deficit, perovskite strain, high recombination rates, shunt paths, etc. In addition, the ill‐defined relations of most of these issues to the WBG perovskites and silicon texture originating from the conflicting research outcomes have become severe impediments to developing PSTSCs. From this perspective, an overview of the recently developed monolithic PSTSCs discussing the major hurdles in their up‐scaling, stabilities, and commercialization is presented.
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