Charge Transport In Materials Research Articles

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.

Evaluating the influence of novel charge transport materials on the photovoltaic properties of MASnI3 solar cells through SCAPS-1D modelling.

In recent decades, substantial advancements have been made in photovoltaic technologies, leading to impressive power conversion efficiencies (PCE) exceeding 25% in perovskite solar cells (PSCs). Tin-based perovskite materials, characterized by their low band gap (1.3 eV), exceptional optical absorption and high carrier mobility, have emerged as promising absorber layers in PSCs. Achieving high performance and stability in PSCs critically depends on the careful selection of suitable charge transport layers (CTLs). This research investigates the effects of five copper-based hole transport materials and two carbon-based electron transport materials in combination with methyl ammonium tin iodide (MASnI3) through numerical modelling in SCAPS-1D. The carbon-based CTLs exhibit excellent thermal conductivity and mechanical strength, while the copper-based CTLs demonstrate high electrical conductivity. The study comprehensively analyses the influence of these CTLs on PSC performance, including band alignment, quantum efficiency, thickness, doping concentration, defects and thermal stability. Furthermore, a comparative analysis is conducted on PSC structures employing both p-i-n and n-i-p configurations. The highest-performing PSCs are observed in the inverted structures of CuSCN/MASnI3/C60 and CuAlO2/MASnI3/C60, achieving PCE of 23.48% and 25.18%, respectively. Notably, the planar structures of Cu2O/MASnI3/C60 and CuSbS2/MASnI3/C60 also exhibit substantial PCE, reaching 20.67% and 20.70%, respectively.

A Review on Preparation Techniques of Charge Transport Layer for Organic and Inorganic Perovskite Solar Cells

The fascinating behavior of charge transport layer in organic and inorganic perovskite solar cells has piqued the interest of designers of semiconductor SnO2 nanoparticles (PSC). The goal of this research is to look at several techniques for manufacturing SnO2 films for use as charge transport layers in PSC. To comprehend the link between the attribute of nanostructured SnO2 films and the efficiency of solar cells, special attention is devoted to the production and properties of the SnO2 thin films. The spin-coating deposition of SnO2 nano fluids generated via surface modification of nano-colloids composed of SnO2 has been one of the key techniques for obtaining SnO2 layers. It has also been reported that preparing SnO2 nanoparticles using Tin (IV) salts results in a high-quality SnO2 film. Light-to-electricity conversion efficiency of about 25.5% has been claimed in many PSC papers [1]. One benefit of adopting SnO2 materials is that they have substantially greater conductivity than TiO2. This work also discusses the production of SnO2 nanoparticles, a different method of generating SnO2 charge transport materials that may be accomplished by the process of freeze-drying precursors known as Tin (IV). SnO2 crystal formation may be regulated at temperatures as low as 700C.

The Effect of Transient Power Ramp‐Up on Structural and Optical Properties of CuO Thin Films Prepared by Radio Frequency Magnetron Sputtering

Transition metal oxides have found application as charge transport materials (CTMs) in perovskite solar cell devices due to their better environmental stability and superior electronic properties compared to organic CTMs. Many researchers have used radio frequency (RF) magnetron sputtering to deposit inorganic CTMs on inorganic layers. However, such efforts on perovskites have been limited by the distortion of high‐energy ions of the sputtering gas energized by the RF power and temperature. The ions may also distort the interface between transparent conducting oxides and the charge transport layers, thereby increasing optical scattering. Thus, the effect of ramp power during RF magnetron sputtering deposition on the structural and optical properties of copper oxide thin films is investigated. While the optical transmittance of the films decreases with increased RF power, it remains the same for all ramped power films; however, it has a similar profile as the highest RF power film. As the ramp power increases, the X‐ray diffraction shows that the films become more polycrystalline with a monoclinic crystal structure. The energy‐dispersive X‐ray spectroscopy results reveal that the atomic concentration of copper slightly increases with the RF power, whereas oxygen concentration slightly decreases.

Performance prediction of perovskite solar cell integrated with lead-free cesium platinum Iodide (Cs2PtI6) absorber and CuInS2 quantum Dot as HTL

Lead-containing perovskite solar cells present significant obstacles to achieving widespread commercial implementation of problems related to their toxicity and stability. Hence, it is critical to contemplate Pt-based all-IPSC as indispensable for rapidly spreading high-performing PSCs. These last several years have witnessed a growing interest in PSCs employing all-inorganic perovskite absorbers, which have garnered plenty of attention arising from their low bandgap and broad high absorption. In this study, we comprehensively investigate a PSC based on Cs2PtI6 using SCAPS. We offer a hypothetical assessment of a Cs2PtI6-based n-i-p organized heterojunction PSC, which is well disposed of and stable without a lead because it utilizes all-inorganic charge-transporting elements. By carefully balancing the thickness of charge transport materials, absorber thickness, defective absorber density, the interface's defect density, series resistance, and shunt resistance, we have achieved a performance-driven PSC with an efficiency of up to 32.77 % at room temperature. Based on our findings, Cs2PtI6 displays excellent potential as an absorbing perovskite for advancing lower poisonous IPSC technology.

Hole and electron transport materials: A review on recent progress in organic charge transport materials for efficient, stable, and scalable perovskite solar cells

Charge transporting materials are essential for fabricating stable and efficient perovskite solar cells. The high-temperature processing, surface defects, and low mobility are common issues in inorganic charge transport materials which can hinder the fabrication of low-cost, efficient, and stable perovskite solar cells. Dopants increase the processing cost of the hole transport materials. Surface defects are observed in the high-temperature processed inorganic electron transport materials. There is a need to develop organic compounds for charge transportation in perovskite solar cells. Herein, the advancements in the organic materials for charge transport in the perovskite solar cells are reviewed. The low-cost processing, better solubility, efficient charge mobility, tunable molecular orbitals, and better stability of organic compounds are some properties for their utilization as charge transport materials in perovskite solar cells. Organic small molecules, polymers, and phthalocyanine compounds can be utilized as dopant-free hole transport materials. Fullerene and non-fullerene derivatives like C60, C70, azaacenes, indacenodithiophene, polymers, and rylene diimides are promising electron transport materials. The functionality, engineering, charge transport properties, and device characteristics of different organic materials are discussed. The review will offer a forecast for improving device stability and efficiency in terms of architecture, engineering, and materials to realize the commercialization of perovskite solar cells soon.

Comprehensive analysis of heterojunction compatibility of various perovskite solar cells with promising charge transport materials

The allure of perovskite solar cells (PSCs), which has captivated the interest of researchers, lies in their versatility to incorporate a wide range of materials within the cell’s structure. The compatibility of these materials plays a vital role in the performance enhancement of the PSC. In this study, multiple perovskite materials including FAPbI3, MAGeI3 and MASnI3 are numerically modelled along with the recently emerged kesterite (CBTS, CMTS, and CZTS) and zinc-based (ZnO and CdZnS) charge transport materials. To fully explore the potential of PSCs and comprehend the interplay among these materials, a total of 18 PSC structures are modeled from different material combinations. The impact of band gap, electron affinity, absorption, band alignment, band offset, electric field, recombination rate, thickness, defects, and work function were analyzed in detail through a systematic approach. The reasons for varying performance of different PSCs are also identified. Based on the simulated results, the most suitable charge transport materials are CdZnS/CMTS for FAPbI3 producing a power conversion efficiency (PCE) of 22.05%, ZnO/CZTS for MAGeI3 with PCE of 17.28% and ZnO/CBTS for MASnI3 with a PCE of 24.17%.

Numerical investigation of lead free Cs2TiBr6 based perovskite solar cell with optimal selection of electron and hole transport layer through SCAPS-1D simulation

Halide-based perovskite has several advantages, including high efficiency, ease of manufacture, and low cost. In general, hazardous lead (Pb) is used in perovskite solar cells as an absorber layer, while polymer, which is unstable in nature used as the electron/hole transport layer. Despite its appealing characteristics, the device uses of lead and degradable components must be addressed. Lead-free titanium-based inorganic perovskite solar cells (PSCs) have drawn strong scientific interest in recent years in order to reduce the possibly detrimental effects of lead on the environment. Titanium is non-toxic, robust, inexpensive, and widely available when compared to other elements. The performance of PSCs is simulated and optimized using the SCAPS-1D software. The effects of various parameters of ZnO and CuSbS2 as charge transport materials on the Cesium Titanium (IV) Bromide (Cs2TiBr6) perovskite solar cell were examined in this study. Results indicate that a highly efficient PSC with a power conversion efficiency (PCE) of 26.96 %, a Voc of 1.0476 V, and an FF of 81.36 % is achieved after numerically optimized the perovskite layer thickness, doping concentration,defect density,and other device input parameters. The observed results are very encouraging and show the potential of Cs2TiBr6 for efficient and environmentally friendly solar applications. The outcomes of this study are likely to not only improve understanding but also motivate further research into the lead-free perovskite solar cell.

A comparative numerical approach between lead-free inorganic Cs2TiBr6 and Cs2PtI6-based perovskite solar cells

Lead halide perovskite has drawn much interest recently because of its impressive optoelectronic performance and unique characteristics. However, concerns regarding its toxicity and instability have hindered the complete industrialization of this material. We propose and investigate the performance of lead-free, eco-friendly, inorganic perovskite solar cells (PSCs) based on Cs2TiBr6 and Cs2PtI6 absorbers in this study. The investigation involved the examination of several parameters, including absorber thicknesses, absorber defect densities, and charge transport material thicknesses. Our findings indicate that Cs2PtI6-based PSCs exhibit superior performance, with an efficiency of 24.49%. In comparison, it is found that the efficiency of PSCs based on Cs2TiBr6 is just 9.81%. The study provides valuable insights into the design of high-performance PSCs for commercial exploitation.

Challenges and Strategies Toward Future Stable Perovskite Photovoltaics

In recent years, perovskite solar cells (PSCs) have received widespread attention due to their superior photovoltaic performance. However, perovskite materials and related films/devices all suffer unfavorable instability issues, which largely hamper their commercialization. In this review, research status, main challenges, and possible strategies to overcome the instability issues in PSCs are comprehensively presented and discussed from four main perspectives, including perovskite, charge transport materials, electrodes, and encapsulations. Related testing standards to accurately evaluate PSC lifetime are also summarized to provide essential guidance toward future advancement of stable PSCs.

Current State and Future Perspectives of Printable Organic and Perovskite Solar Cells.

Photovoltaic technology presents a sustainable solution to address the escalating global energy consumption and a reliable strategy for achieving net-zero carbon emissions by 2050. Emerging photovoltaic technologies, especially the printable organic and perovskite solar cells, have attracted extensive attention due to their rapidly transcending power conversion efficiencies and facile processability, providing great potential to revolutionize the global photovoltaic market. To accelerate these technologies to translate from the laboratory scale to the industrial level, it is critical to develop well-defined and scalable protocols to deposit high-quality thin films of photoactive and charge-transporting materials. Herein, the current state of printable organic and perovskite solar cells is summarized and the view regarding the challenges and prospects toward their commercialization is shared. Different printing techniques are first introduced to provide a correlation between material properties and printing mechanisms, and the optimization of ink formulation and film-formation during large-area deposition of different functional layers in devices are then discussed. Engineering perspectives are also discussed to analyze the criteria for module design. Finally, perspectives are provided regarding the future development of these solar cells toward practical commercialization. It is believed that this perspective will provide insight into the development of printable solar cells and other electronic devices.

Solution Processed Light Emitting Diode Based on InP Quantum Dots with Hybrid Emissive Layer

Solution-processable Cadmium-based Quantum dots light emitting diodes (QLEDs) are regarded as a good candidate for good performance display devices due to excellent color purity and inexpensive production. However, the toxicity still poses a severe risk. Although the most effective cadmium-free substance is thought to be InP for producing efficient QLEDs, its efficiency falls far short of its cadmium-based counterparts. We made a homogeneous thin film by mixing the organic compound 4, 4-bis (N-carbazyle)-1, 1-biphenyl (CBP) with InP/ZnSe quantum dots (QDs). Then, in our QLED design, we utilized this film as an emissive layer. The new QDs-based device showed a higher luminance of 14600 cd/m2 and having higher external quantum efficiency (EQE) of 11.6%. We discovered that the mixed QDs without any phase separation had a consistent distribution of CBP, which facilitated transfer of energy to QDs and injection of holes into the emissive layer. The blended QD was also shown to restrict injection of electrons into the hole transport/injection layers, protecting the device’s structural integrity. Developing a balanced charge in stable optoelectronic devices densities has a high potential when a homogeneous QD layer is combined with an effective charge transport material.

Symmetry-Breaking Charge Separation in a Chiral Bis(perylenediimide) Probed at Ensemble and Single-Molecule Levels.

Chiral molecular assemblies exhibiting symmetry-breaking charge separation (SB-CS) are potential candidates for the development of chiral organic semiconductors. Herein, we explore the excited-state dynamics of a helically chiral perylenediimide bichromophore (Cy-PDI2) exhibiting SB-CS at the ensemble and single-molecule levels. Solvent polarity-tunable interchromophoric excitonic coupling in chiral Cy-PDI2 facilitates the interplay of SB-CS and excimer formation in the ensemble domain. Analogous to the excited-state dynamics of Cy-PDI2 at the ensemble level, single-molecule fluorescence lifetime traces of Cy-PDI2 depicted long-lived off-states characteristic of the radical ion pair-mediated dark states. The discrete electron transfer and charge separation dynamics in Cy-PDI2 at the single-molecule level are governed by the distinct influence of the local environment. The present study aims at understanding the fundamental excited-state dynamics in chiral organic bichromophores for designing efficient chiral organic semiconductors and applications toward charge transport materials.

Morphological, Photoluminescence, and Electrical Measurements of Rare-Earth Metal-Doped Cadmium Sulfide Thin Films.

This work is aimed at investigating the viability of utilizing cadmium sulfide (CdS) as a buffer layer in CdTe solar cells by analyzing and assessing its optical, photoluminescence, morphological, and electrical properties. These films were fabricated using a thermal coating technique. Optical microscopy was used to observe the changes in morphology resulting from the doping of rare-earth metals such as samarium (Sm) and lanthanum (La) to CdS, while the granular-like structure of the sample was confirmed by scanning electron microscopy. The objective of incorporating Sm and La ions into CdS was to enhance photoconductivity and optimize the optical bandgap, aiming to create a viable charge transport material for photovoltaic devices with enhanced efficiency. Through that process, a noticeable decrease in transmission, from approximately 80 to 68% in the visible region, was observed. Additionally, the bandgap value was reduced from 2.43 to 2.27 eV. Furthermore, during the analysis of the photoluminescence spectra, it was observed that emission peaks occurred in the visible region. These emissions were attributed to electronic transitions that took place via band-to-band and band-to-impurity interactions. The electrical measurements showed an enhancement in conductivity due to the decrease in the bandgap. This notable consequence of the doped materials suggests their utilization in photovoltaic systems.