Charge Transport In Materials Research Articles

Synthesis, crystal structure, spectral, and DFT analysis of 2-(2,3,4-trimethoxyphenyl)-1H-phenanthro[9,10-d]imidazole as charge transport material

Synthesis, crystal structure, spectral, and DFT analysis of 2-(2,3,4-trimethoxyphenyl)-1H-phenanthro[9,10-d]imidazole as charge transport material

Furan-substituted benzodithiophene-based polymer semiconductor for charge transport materials in organic transistors and nanocrystal photovoltaics

Furan-substituted benzodithiophene-based polymer semiconductor for charge transport materials in organic transistors and nanocrystal photovoltaics

Evaluation of the electrochemical response of aromatic peptides for biodetection of dopamine

Biologically inspired aromatic peptide-based materials are gaining increasing interest as novel charge transport materials for bioelectronics due to their remarkable electrical response and inherent biocompatibility. In this work, the electrochemical response of ten aromatic amino acids and eleven aromatic peptides has been evaluated to assess the potential of incorporating peptides into electrochemical sensors not as biorecognition elements but as biocompatible electronic materials. While the electrochemical response of amino acids is null in all cases, the hexapeptide of phenylalanine (Phe) capped with eight polyethylene glycol units at the N-terminus and, especially, the cyclic dipeptide formed by two dehydro-phenylalanine residues (cyclo(ΔPhe2)), which organize in fibrillary self-assembled structures of nano- and submicrometric size, respectively, are the most electroactive peptides. Electrodes to electrochemically detect the oxidation of dopamine have been prepared using a plasma-activated polyethylene terephthalate glycol substrate covered with a poly(3,4-ethylenedioxythiophene) layer and a peptide coating deposited at the surface. The highest analytical sensitivity and the lowest limits of detection and quantifications have been obtained for the electrode coated with cyclo(ΔPhe2), which shows much better results than that without peptide. These results, on the one hand, confirm the significant role of electron transport through π-stacking interactions in the electrochemical response of peptides and, on the other hand, demonstrate that peptides can be directly used as electronic materials rather than as simple recognition elements in electrochemical biosensors.

A Graded Redox Interfacial Modifier for High-Performance Perovskite Solar Cells.

Perovskite solar cells have emerged as a potential competitor to the silicon photovoltaic technology. The most representative perovskite cells employ SnO2 and spiro-OMeTAD as the charge-transport materials. Despite their high efficiencies, perovskite cells with such a configuration show unsatisfactory lifespan, normally attributed to the instability of perovskites and spiro-OMeTAD. Limited attention was paid to the influence of SnO2, an inorganic material, on device stability. Here we show that improving SnO2 with a redox interfacial modifier, cobalt hexammine sulfamate, simultaneously enhances the power-conversion efficiency (PCE) and stability of the perovskite solar cells. Redox reactions between the bivalent cobalt complexes and oxygen lead to the formation of a graded distribution of trivalent and bivalent cobalt complexes across the surface and bulk regions of the SnO2. The trivalent cobalt complex at the top surface of SnO2 raises the concentration of (SO3NH2)- which passivates uncoordinated Pb2+ and relieves tensile stress, facilitating the formation of perovskite with improved crystallinity. Our approach enables perovskite cells with PCEs of up to 24.91%. The devices retained 93.8% of their initial PCEs after 1000 hours of continuous operation under maximum power point tracking. These findings showcase the potential of cobalt complexes as redox interfacial modifiers for high-performance perovskite photovoltaics.

Unveiling the potential of FASnI3 solar cells through advanced charge transport materials: A SCAPS-1D perspective

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 FASnI3 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/FASnI3/Cu2O/Au with aVoc of 2.05 V, Jsc of 29.316 mA/cm2, FF of 53.37 %, and power conversion efficiency (PCE) of 32.13 %, providing valuable insights in optimizing FASnI3 solar cells and advancing next-generation solar energy conversion technologies.

Enhancing tetrafullerene based photosensors and photovoltaic cells by graphene oxide doping

This study explores the postulated potential of tetrafullerene as a charge transport material when combined with dispersed graphene oxide (GO), over concerns about fullerene’s limited performance in similar devices. Incorporating GO is expected to augment carrier concentration, increase surface area, and reduce operating voltages. Devices fabricated with p-Si/tetrafullerene with varying GO concentration exhibit notable enhancements in both dark and illuminated characteristics. The results demonstrate improved electron concentration and transport, leading to enhanced rectification ratios, ideality factors, and interface state densities across a broad bias and illumination range. Notably, devices doped with 0.2GO exhibit the most promising electrical and photoresponse characteristics, showcasing potential for applications in photosensing and photovoltaics.

Exploring eco-friendly novel charge transport materials for enhanced performance of tin based perovskite solar cell

This pioneering simulation study explores the potential of perovskite materials, particularly the non-toxic methyl ammonium tin iodide (MASnI3), in solar cell technology. The investigation focuses on eco-friendly, solution-processed compounds—specifically, WO3 and In2S3 as Electron Transport Layers (ETL) and MoO3 and WSe2 as Hole Transport Layer (HTL)—to develop planar n-i-p MASnI3 perovskite solar cell (PSC) devices. WO3 is chosen for its solution processing and high electron mobility, while In2S3 offers n-type properties, superior carrier mobility, non-toxicity, and thermal durability. MoO3 and WSe2 are selected as HTLs for their efficient charge transport capabilities. Utilizing the solar cell capacitance simulator (SCAPS-1D) software, the study systematically evaluates alternative charge-selective materials, considering various parameters such as thickness (0.1 µm to 1.5 µm for absorber and 0.1 µm to 0.35 µm for CTLs), doping concentration (3.2E10 to 3.2E16 for absorber and E16 to E20 for CTLs), defect density, and energy band offset for MASnI3 PSCs. Four distinct n-i-p device structures are optimized, yielding impressive PCE improvements ranging from 14.63 % to 25.34 %, a significant 3 % enhancement compared to initial results. Notably, the WO3/MASnI3/WSe2 configuration exhibits limitations in electrical performance, while the other optimized structures demonstrate substantial efficiency gains. Further analysis investigates the impact of reflecting coatings (10 % to 90 %), varying contact work functions (5.2–5.8 eV), and temperature (300–400 K) on photovoltaic parameters. Critical factors including energy band offset, recombination current profile, and built-in potential, are meticulously examined, laying the groundwork for advanced PSC implementation. The study culminates in the In2S3/MASnI3/MoO3 device configuration, which achieves a peak efficiency of 25.34 %, showcasing superior thermal stability and an enhanced fill factor, thus propelling all-inorganic PSCs towards practical implementation.

Porphyrin-Based Hole-Transporting Materials for Perovskite Solar Cells: Boosting Performance with Smart Synthesis.

Perovskite solar cells (PSCs) are becoming a promising and revolutionary advancement within the photovoltaic field globally. Continuous improvement in efficiency, straightforward processing methods, and use of lightweight and cost-effective materials represent superior features, among other notable aspects. Still, long-term stability and durability are issues to address to facilitate widespread commercial adoption and practical application prospects. Research has focused on overcoming these challenges, and charge transport materials play a critical role in determining charge dynamics, photovoltaic performance, and device stability. Conventional hole-transporting materials (HTMs), spiro-OMeTAD and PTAA, contribute to remarkable power conversion efficiencies owing to high thin-film quality and matched energy alignment. However, they often show a high material cost, low carrier mobility, and poor stability, which greatly limit their practical applications. Now, this review outlines recent advances in synthetic approaches to porphyrin-based HTMs to tune the charge dynamics by optimizing their molecular structures and properties. The main structural features comprise porphyrins of A4-type, trans A2B2-type, and photosynthetic pigment analogues. Strategies include well-established routes to provide the required macrocycles, such as condensation of pyrrole or dipyrromethanes with suitable aldehydes, metalation of the porphyrin inner core, and postfunctionalization of peripheral positions. These functionalizations involve conventional procedures (e.g., halogenation, esterification, transesterification, nucleophilic oxidation, reduction, and nucleophilic substitution) as well as metal-catalyzed ones such as Suzuki-Miyaura, Sonogashira, Buchwald-Hartwig, and Ullmann cross-coupling reactions. As HTMs can also protect the perovskite layer from the external environment, porphyrin structures play a pivotal role in chemical, mechanical, and environmental stability, with their high hydrophobicity ability as the most significant parameter. The impact of porphyrins on the hole hopping of other HTMs while acting as an additive or an interlayer, passivating defects, and improving charge transport is also highlighted to provide real insights into ways to develop efficient and stable porphyrin-based materials for PSCs. This perspective aims to guide the scientific community in the design of new porphyrin molecules to place PSCs as an outperformer in photovoltaic technologies.

The performance of triethanolamine (TEOA)-doped Poly(3,4-ethylenedioxythiophene): Polystyrene sulfonate on MAPbI3-based solar cells

For over a decade, perovskite-based solar cells have attracted a good deal of attention due to their unique characteristics. Charge transport materials (CTMs) have a vital function in the performance of perovskite solar cells properly. Therefore, it is crucial to choose a suitable and affordable CTM. A commonly regarded conductive polymer combination called poly (3,4 ethylenedioxythiophene)-poly (styrene sulfonate) (PEDOT:PSS) is mainly employed in organic and perovskite solar cells (PSCs) as a hole transport layer (HTL). Although PEDOT:PSS has benefits including affordability, simplicity, low-temperature processing, and ease of production, its acidic nature and low electrical conductivity pose drawbacks. In this research, it has been demonstrated that adding triethanolamine (TEOA) to the PEDOT:PSS solution improves the photovoltaic (PV) performance of sol-gel-based PSCs. The combination of enhanced conductivity and hole mobility of PEDOT:PSS layer with reduced perovskite trap density resulted in a more than 32 % boost in efficiency and better stability due to the basic characteristics of triethanolamine as well.

Enhancing efficiency in inverted perovskite solar cells: The role of dual-site binding ligands

Despite the rapid progress in efficiency, PSCs encounter substantial challenges regarding durability and scalability. Inverted p-i-n PSCs provide enhanced long-term operating stability over the conventional n-i-p structures but lag in PCE (Park and Zhu, 2020 [3]). This limitation is mainly due to the interface between the perovskite light-absorbing layer and charge transport materials, where energy band misalignment and energy level pinning hinder PCE. Furthermore, surface defects exacerbate these constraints. In the endeavor to improve performance of PSCs, surface passivation is crucial for reducing nonradiative recombination at the interface. A recent study by Chen et al., published in the journal Science, introduces an innovative interface passivation strategy for p-i-n PSCs that could set a new benchmark for efficiency and stability (Chen et al., 2024 [4]). This commentary assesses the potential impact of dual-site-binding ligands on PSCs and anticipates their transformative effect on the field.

Photocurrent interference spectroscopy of solids and characterization of semiconductor solar-cell materials

Photocurrent measurements are widely used to study the intrinsic optoelectronic properties of semiconductors, such as photocarrier generation efficiency and carrier mobility, as well as evaluate the performance of optoelectronic devices, such as solar cells and photodetectors. Interferometric spectroscopy precisely measures optical properties and gathers optical spectra information on semiconductors. Consequently, photocurrent-based interferometric measurements, with high signal-to-noise ratios, high resolution, and broad frequency bandwidths, can probe the energy distributions of low-density defects and impurities and investigate charge transport in materials and devices. Here, we demonstrate that photocurrent interference spectroscopy reveals the intrinsic properties of solar-cell materials: bulk crystals of GaAs and halide perovskite, and thin films of halide perovskite and quantum dot. We show that homodyne interference spectroscopy of photocurrent can monitor low-density localized states in semiconductors and that it can be used in combination with other spectroscopy techniques, such as photoluminescence measurements, to provide a deep understanding of photocurrent generation processes. Furthermore, we show that heterodyne interference spectroscopy of photocurrent can be used to investigate the frequency dependence of material parameters, such as the dielectric constant, absorption coefficient, and reflectance. As an application, we used interference spectroscopy of photocurrent to show the impact of multiexcitons on the photoabsorption and photocarrier generation processes in quantum dot solar cells. Finally, we used it to reveal the distinctive spectral characteristics at the band edge of a halide perovskite, which is considered to be an exceptional solar-cell material with high energy conversion efficiency.

Carrier transport layer engineering of Cs2TiI2Br4 halide double perovskite solar cell via SCAPS 1D: Approaching the Shockley-Queisser limit

All-inorganic Cs2TiIxBr(6-x)-based perovskite solar cells (PSCs) are recently attracting a lot of attention for their tunable bandgaps, earth abundance, non-toxicity, and ultra-stability. Among the Cs2TiIxBr(6-x) family of materials, Cs2TiI2Br4 with a bandgap of ∼1.38 eV has the potential to be an excellent single junction solar cell material with a theoretically higher Shockley-Queisser limit of power conversion efficiency (PCE). Its excellent optoelectronic properties make it a potential candidate for being the highest-performing PSC from the Cs2TiIxBr(6-x) family. In our study, a total of eight hole transport materials (P3HT, PTAA, Spiro-OMeTAD, PEDOT:Pss, CuSCN, CuI, NiO, and MoO3) and six electron transport materials (PCBM, TiO2, CdS, SnO2, ZnO, and IGZO) were investigated to select suitable charge transport materials. The defect densities of interface and absorber, different absorber layer thicknesses, several metal work functions, series-shunt resistance, and temperature were investigated to derive the conditions for optimum performance. After thorough investigation, we derived four novel devices with the combination of all the organic and inorganic charge transport materials to provide optimum performance. Among them, the combination of inorganic SnO2 and CuSCN as electron and hole transport layer respectively achieved the highest PCE of 23.41 %.

Computational analysis of ternary cation perovskite based solar cells employing transition metal chalcogenide, graphene derivatives, and SWCNT as hole transport layers

In this study, a numerical modelling on device configurations composed of Cs3Bi2I9 as the absorber material is performed by choosing diverse hole transport layers (HTLs) such as Cu2Te, graphene oxide (GO), reduced graphene oxide (rGO) and single walled carbon nanotube (SWCNT). All device configurations exhibit excellent PCE when the design parameters of perovskite, charge transport materials are optimized. The PCE of the device configurations with Cu2Te, GO, rGO and SWCNT as HTL is estimated as 10.81%, 10.87%, 9.99% and 11% respectively on optimizing design parameters of layers of the device. The perovskite solar cell (PSC) design is further optimized for suitable back metal contact and the device with rGO as the HTL shows an enhancement in PCE from 9.99% to 11.62% when Au is replaced by Se with a work function of 5.9 eV. Among the device configurations with distinct HTLs analysed, the FTO/ZnO/Cs3Bi2I9/rGO/Se configuration achieves the maximum PCE of 11.62%, indicating that rGO is the most suitable HTL material among the chosen ones. All modelled devices exhibit a gradual decline in PCE with temperature, except the PSC with SWCNT as the HTL, which shows a sudden performance degradation with temperature.

Modeling and performance investigation of novel inorganic Cs4CuSb2Cl12 nanocrystal perovskite solar cell using SCAPS-1D

For the next generation of photovoltaic devices, perovskite solar cells (PSCs) appear as a good choice because they are simple and convert energy to electricity very efficiently. Recent years have seen a great deal of interest in organic-inorganic lead halide perovskites due to their exceptional optoelectronic properties. Nonetheless, additional commercialization of the Pb element is still restricted by its inevitable toxicity. To address the instability and toxicity of the lead hybrid perovskite, it is imperative to produce entirely inorganic lead-free perovskite nanocrystals. Cs4CuSb2Cl12 offers promising qualities and strong stability against light, heat, and humidity to overcome these drawbacks. It possesses an efficient photo-generated carrier and good carrier mobility. In this study, a lead-free perovskite solar cell with the novel configuration of FTO/WS2/Cs4CuSb2Cl12/CuSbS2/Ni has been optimized using SCAPS-1D simulation software and investigates the potential of Cs4CuSb2Cl12 nanocrystal solar cell. The impact of different characteristics of charge transport materials on Cs4CuSb2Cl12 nanocrystal solar cells has been reported. Additionally, the study computationally optimizes the thickness of perovskite layer, doping concentration, defect density, and other input parameters to propose an effective PSC with power conversion efficiency of 23.10 %, Voc of 1.1675V, and FF of 83.33 %.

Rational Design of Bio‐Inspired Peptide Electronic Materials toward Bionanotechnology: Strategies and Applications

AbstractBiologically inspired peptide‐based materials, as novel charge transport materials, have gained increasing interest in bioelectronics due to their remarkable electrical properties and inherent biocompatibility. Extensive studies have shown that peptides can self‐assemble into a variety of hierarchical nanostructures with unique physical properties through supramolecular interactions. Therefore, peptide‐based materials hold great promise for applications in emerging electronic fields such as sensing, energy harvesting, energy storage, and electronic transmission. Herein, this work proposes a review article to summarize the rational design and research progress of peptide‐based materials and devices in bioelectronics. This work first introduces the design strategies and assembly mechanism for constructing high‐performance peptide‐based electronic materials and devices. In the following part, the applications of peptide‐based electronic materials and devices are systematically classified and discussed, including sensors, piezoelectric nanogenerators, electrodes, and semiconductors. Finally, the remaining challenges and future perspectives of peptide‐based bioelectronic materials and devices are presented. This work believes that this review will provide inspiration and guidance for the design and development of innovative peptide‐based smart materials in the field of bioelectronics.

Probing the Reactivity of ZnO with Perovskite Precursors.

To achieve more stable and efficient metal halide perovskite devices, optimization of charge transport materials and their interfaces with perovskites is crucial. ZnO on paper would make an ideal electron transport layer in perovskite devices. This metal oxide has a large bandgap, making it transparent to visible light; it can be easily n-type doped, has a decent electron mobility, and is thought to be chemically relatively inert. However, in combination with perovskites, ZnO has turned out to be a source of instability, rapidly degrading the performance of devices. In this work, we provide a comprehensive experimental and computational study of the interaction between the most common organic perovskite precursors and the surface of ZnO, with the aim of understanding the observed instability. Using X-ray photoelectron spectroscopy, we find a complete degradation of the precursors in contact with ZnO and the formation of volatile species as well as new surface bonds. Our computational work reveals that different pristine and defected surface terminations of ZnO facilitate the decomposition of the perovskite precursor molecules, mainly through deprotonation, making the deposition of the latter on those surfaces impossible without the use of passivation.

Exploring the potential of MAGeI3 perovskite cells with novel charge transport material optimization

Germanium-perovskites have emerged as alternatives to lead-perovskites due to similar photovoltaic properties but lower efficiency (PCE) because of a larger band-gap. However, the efficiency of the cells can be enhanced by using novel charge transport materials (CTL) and optimizing design parameters. In this work, methyl-ammonium germanium triiodide (CH3NH3GeI3) cells were analyzed in detail using SCAPS-1D. 20 distinctive structures were modeled using 9 different CTLs. The different structures produced varying results with efficiencies ranging from 3.68% to 20.79%. A systematic investigation was carried out to analyze the effect of CTL, absorption/transmittivity, band-alignment, band-offset, electric-potential, recombination, thickness, doping, temperature, and reflective-coating on the cell’s performance. The reasons for varying performance of the structures were identified and enhanced through design optimization. Initially, for the optimization, the perovskite defect density (1 ×1014 cm−3) and interface defect densities (1 ×1011 cm−2) were kept constant. The structures with proper band-alignment achieved optimized thickness between 900–1100 nm and those with band offsets achieved between 500–700 nm. While the optimized doping for the perovskite was found to be 1 × 1015 cm2. The CTL performed best with minimum thickness (100 nm) and high doping concentration (1 ×1020 cm2). Increasing the defect density impacted the optimized thickness by reducing it to 100 nm for all structures with PCE between 0.06% to 3.2% at 1 × 1018 cm−3. The proposed structures with optimized parameters resulted in enhanced performance, with structures seeing an improved efficiency of up to 8%. The best result is achieved with SnO2/Per/CuAlO2 having PCE of 25.43%, Jsc of 16.18 mA/cm2, Voc of 1.77 V and F.F of 89.02%.

All‐Inorganic Perovskite Solar Cells: Modification Strategies and Challenges

Cesium‐based all‐inorganic wide‐bandgap perovskite solar cells (AIWPSCs) have been demonstrated with exceptional optoelectronic properties such as intrinsic optical wide‐bandgap and high thermal stability, which make them suitable candidates for the front sub‐cells of tandem solar cells (TSCs). Passivation of perovskite surface and interface is a matter of common interest in this community since all‐inorganic perovskites always suffer from non‐ideal crystallization such as phase impurity, high defect density, and non‐uniform morphology. Despite these shortcomings, numerous efforts have been devoted in recent years to pursuing high‐performance AIWPSCs, which exhibit an abruptly increased power conversion efficiency (PCE) from 2.9% to over 21.0%. In view of not having a thorough summary about the advancements on AIWPSCs, herein, a comprehensive review is given to highlight the recent device performance progress of AIWPSC, particularly focusing on the strategies to passivate the defects of all‐inorganic perovskite, namely, additive engineering, solvent engineering, interface modification, and the exploration of new charge transport materials (CTMs) for improving the phase stability and PCE of AIWPSCs. Finally, a conclusive outlook on AIWPSCs will be given to provide our perspectives aiming to inspire the further development of AIWPSCs.

Theoretical investigations on electronic structure and optoelectronic properties of vinyl fused monomeric and oligomeric benzimidazole derivatives using DFT and TDDFT techniques.

The present work encompasses the theoretical investigation of 14 benzimidazole-based (seven vinyl fused monomeric benzimidazole (VFMBI) and seven vinyl fused oligomeric benzimidazole (VFOBI)) derivatives using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) techniques. The effects of electron donor and acceptor groups on the electronic structure such as HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies, HOMO-LUMO energy gap, ionization potentials (IPs), electron affinities (EAs), internal reorganization energies of holes and electrons (λh/e), and excited state properties have been explored in the present work. In addition, natural bond orbital (NBO) analysis of these compounds has been investigated to reveal the typical stabilization interactions in these molecules. Hence, the aim of the present work is to explore the electronic structures and optoelectronic properties of the title molecules on the basis of the DFT quantum chemical calculations and to make an idea on the parameters influencing the optoelectronic efficiency toward a better understanding of the structure-property relationships. Moreover, the calculated results reveal the suitable optoelectronic properties of benzimidazole oligomer derivatives using theoretical techniques. Of the investigated molecules, 4_MABIMCY and 4_MABIOCY show potential optoelectronic properties and can be used as a potential charge transport material due to their narrow band gap, high hyperpolarizability, low ionization potential, and high electron affinity. The larger λab and λem values favor the system to be used as a potential optoelectronic material with better optical properties. All quantum chemical calculations were carried out using Gaussian09 theoretical chemistry code. Ground state calculations were made using the B3LYP/6-31+G(d,p) method. All excited state calculations had been computed using TDB3P86/6-311++(d,p). The initial structure for excited state calculations was optimized using the AM1 semi-empirical method.

New fluorene-based bipolar charge transporting materials.

Air-stable and solution-processable fluorene-based bipolar charge transporting materials (CTMs) were designed, synthesized, and analyzed. These CTMs feature anthraquinone, 9-fluorenone, and 9-dicyanofluorenylidine groups and exhibit good film formation properties for solvent processing. Quantum chemistry simulations and optical absorption measurements proved that several stable conformers and charge transfer complexes form inside the molecules. Hole mobilities in CTMs were around 10-4 to 10-5 cm2 V-1 s-1, while electron mobility in compounds with anthraquinone and 9-dicyanofluorenylidine groups was approximately one order of magnitude lower.