Hole Transport Research Articles

Improvement of Performance of Perovskite Solar Cell By in-Plane Design

Perovskite solar cells (PSCs) have attracted attention as one of the next-generation solar cell. To enhance power conversion efficiency (PCE) of PSCs, a great deal of research has been conducted so far, mainly in the field of material development. However, in-plane cell design for evaluating the performance of PSCs are currently not standardized. In this study, optimization of device structures was investigated for the aim of to minimize charge transfer losses and improve FF and PCE.The fabrication of perovskite solar cell is as follows; (i) as the electron transport layer (ETL), compact TiO2 and mesoporous TiO2 were deposited on FTO glass substrates by spray coating and spin-coating. (ii) K0.025(Cs0.1FA0.9)0.975PbI3 perovskite was deposited by spin-coating using the anti-solvent method1). (iii) Spiro-OMeTAD was spin-coated as the hole transport layer. (iv) The electrodes were insulated by laser etching. (v) Finally, Au was vacuum-deposited and laser-etched again to fabricate the cell.Throughout the two laser etching stages in the cell fabrication process, adjustments are made to the shapes of the ETL/perovskite layer/HTL and the Au electrode. Specifically, performance was compared for three patterns of devices; (a) round-shaped generator section and current-collecting bridge, (b) shorter distance of current-collecting bridge, (c) shorter distance of current-collecting bridge and same width of current-collecting bridge as generator section. Photoelectric conversion characteristics was determined based on I-V characteristics measured under quasi-sunlight (AM 1.5, 100 mW/cm2) irradiation. In all cases, the shading mask area was kept constant at 0.18 cm2.Figure shows images of three patterns of the results of comparing FF from I-V measurements for each device with varying shapes. It can be seen that even PSCs fabricated from the same material exhibit different FF values depending on the cell shapes. PCE and FF were higher in (b) than in (a), with the highest values observed for devices of (c), in which the collector bridge is shortened and the width is increased. In addition, the series resistance (Rs) and shunt resistance (Rsh) were approximated from the slope of the I-V curve. Among the internal resistances, the series resistance (Rs) decreased, leading to an improvement in FF. This is thought to be due to the decrease of series resistance of electron and hole transfer. Figure 1

Optimizing non-toxic (CH3NH3)3Bi2I9 perovskite solar cells by SCAPS-1D

Abstract Low-dimensional bismuth-based perovskite solar cells (PSCs) have demonstrated some benefits over lead-based PSCs for nontoxicity and remarkable stability. These two factors are now the primary concerns in the photovoltaic community. The power conversion efficiency (PCE) of PSCs using the lead Pb-free chemical methylammonium bismuth iodide (CH3NH3)3Bi2I9 is severely limited due to the poor quality of the photoactive material. Herein, the photovoltaic performance of the (CH3NH3)3Bi2I9 PSCs was investigated. The objective of this study was to investigate the intrinsic impacts of (CH3NH3)3Bi2I9 perovskite by using SCAPS-1D (Solar Cell Capacitance Simulator) to simulate the PSCs and the adjustment of relevant physical parameters to closely match experimental results. Moreover, the cells were optimized based on (CH3NH3)3Bi2I9 film thickness, total defect density of (CH3NH3)3Bi2I9, optical bandgap, and interfacial defects. By conducting a comprehensive analysis of the current-voltage (J-V) plots and quantum efficiency feature, the best values of perovskite thickness, bandgap, and defect density were determined to be 100 nm, 1.6 eV, and 1014 cm-3, respectively. Furthermore, defects in the interfaces between the electron-transporting layer (ETL)/(CH3NH3)3Bi2I9 and hole transport layer (HTL)/(CH3NH3)3Bi2I9 were considered, and their influence on performance was also investigated. Accordingly, the optimized cell has realized a record PCE of 9.043% and a high quantum efficiency exceeding 60%, which is comparable to those of some Pb-free perovskite analogues. The operational temperature calucations showed that all parameters remain relatively constant with increasing temperature. Therefore, the results imply that the simulated Pb-free PSCs can be stable in a thermal environment. The proposed structural layout and optimization approach can encourage more study and actual applications for Pb-free organometallic perovskite solar cells.

Ferrocene Based Metal-Organic Framework-Carbon Nanotubes Composite in a Zn-Ion Battery Charged By a Novel Perovskite Solar Cell

A non-aqueous Zinc-ion battery is fabricated in air with a distinctive configuration comprising CoFe-ferrocene dicarboxylic acid (FcDA) metal organic framework/carbon nanotubes (CNTs) composite acting as cathode and the counter electrode being Zn powder (Zn PW)/coffee activated carbon (Zn/Cl-AC). A perovskite (PSK) solar cell is used to charge ZIB. The PSK solar cell is characterized by a n-i-p based architecture, wherein the Cs0.1Fa0.9PbI3 perovskite (PSK) acts as the photo-sensitive electrode and carbon paste as the hole transport layer. The PSK was modified with tetra-butyl ammonium perchlorate (TBAP) to passivate defects via electrostatic interactions and hydrogen bonding. Further the butyl chains provided moisture resistance due to their hydrophobic nature. CoFe-FcDA/CNTs//Zn PW/Zn/Cl-AC battery when electrically charged upto 1.8 V delivers a discharge capacity of 250 mAh/g at 40 mA/g current density. When the cell is photo-charged to 1.5 V in the absence of any bias it delivers a discharge capacity of 164 mAh/g at the same current density. The ZIBs gets rapidly photo-charged in just ~5.6 mins making this a standalone solar powering unit for portable electronic devices. Solar charged battery is first of its kind which can sustain photo-charging and dark discharge at 300 mA/g current density with retention of ~82% and the overall solar conversion efficiency declines from 7.6% to 6.3%. The results indicate the cyclability of the integrated system and stability of PSK-TBAP solar cell. Figure 1

High Throughput Solution Combustion Generated Nickel Oxide Films As a Hole Transport Layer for Perovskite Photovoltaics

Nickel oxide remains a prominent hole transport layer (HTL) for use in inverted perovskite photovoltaic devices owing to its high optical transmission as a thin film, hole mobility, and chemical tunability. Numerous approaches have been posited for forming high quality nickel oxide thin films with solution combustion synthesis (SCS) as one of the most promising to yield high quality oxide thin films at high throughputs. However, the resulting characterization of the nickel oxide generated can be challenging owing to nickel oxide’s surface reactivity under ambient conditions and its instability against common laboratory techniques such as X-ray photoelectron spectroscopy (XPS) with argon depth sputtering.Here, we present a multi-modal synchrotron radiation characterizations of nickel oxide thin films generated via solution combustion synthesis with a curing duration of 1 min at 300 ºC for perovskite solar cells. We explore the role of varying the ligand structure and fuel/oxidant ratio of the nickel oxide precursor and assess the resulting properties of the nickel atoms using extended X-ray absorption fine structure, ex situ X-ray absorption near edge spectroscopy, and grazing-incidence X-ray diffraction along with lab-scale XPS. We have also performed some of the first in situ analysis of the combustion process using synchrotron radiation with 5 second time resolution. As a result, we can provide unprecedented sensitivity to correlate between the chemical state of Ni in the film bulk and surface to device performance and stability.

Self‐Powered UV Photodetectors With Ultrahigh Performance Enabled by Graphene Oxide‐Modulated CuI Hole Transport Layer

Self‐Powered UV Photodetectors With Ultrahigh Performance Enabled by Graphene Oxide‐Modulated CuI Hole Transport Layer

Solar Batteries Utilizing Charge Storage and Light Absorption in Bifunctional Carbon Nitrides

Herein, we report a solar battery, that combines both solar cell and battery in one device. It uses the carbon nitride K-PHI as a bifunctional photoanode to absorb light and store photoexcited electrons, the conductive organic polymer PEDOT:PSS as a cathode to store photoexcited holes, and the organic hole transport material F8BT as a multifunctional separator. The separator is not only tasked with preventing self-discharge and shuttling ions, but also with providing rectified hole transfer from anode to cathode via an internal hole transfer cascade. We present both theoretical studies and a proof-of-concept device, that shows a 243 % increase in extracted charge when discharged under illumination compared to operation in the dark. The environmentally friendly, chemically robust, and biocompatible nature of K-PHI opens up a plethora of future applications in the growing field of optoionic devices.

Reaction-Type-Dependent Behavior of Redox-Hopping in MOFs─Does Charge Transport Have a Preferred Direction?

Redox hopping is the primary method of electron transport through redox-active metal-organic frameworks (MOFs). While redox hopping adequately supports the electrocatalytic application of MOFs, the fundamental understandings guiding the design of redox hopping MOFs remain nascent. In this study, we probe the rate of electron and hole transport through a singular MOF scaffold to determine whether the properties of the MOF promote the transport of one carrier over the other. A redox center, [RuII(bpy)2(bpy-COOH)]2+, where bpy = 2,2'-bipyridine and bpy-COOH = 4-carboxy-2,2'-bipyridine, was anchored within NU-1000. The electron hopping coefficients (De) and ion diffusion coefficients (Di) were calculated via chronoamperometry and application of the Scholz model. We found that electrons transport more rapidly than holes in the studied MOF. Interestingly, the correlation between De and self-exchange rate built in previous research predicted reversely. The contradicting result indicates that spacing between the molecular moieties involved in a particular hopping process dominates the response.

Comprehensive device simulation of perovskite solar cell with CuFeO2 as hole transport layer

Abstract Solid-state organic-inorganic halide perovskite solar cells have attracted increasing interest due to their potential as high-efficiency, low-cost photovoltaic devices. In this study, we comprehensively simulate CH₃NH₃PbI₃ perovskite-based solar cells with CuFeO₂ as the hole transport material (HTM) layer, and compare them to cells using Spiro-OMETAD and Cu₂O as HTM layers, utilizing SCAPS-1D software. The effects of absorber thickness, back contact work function, CuFeO₂ thickness, acceptor concentration, and defect density at the CH₃NH₃PbI₃/CuFeO₂ interface are analyzed. The results indicate that delafossite CuFeO₂ is a promising HTM that could significantly enhance the performance of perovskite-based solar cells. TiO₂/CH₃NH₃PbI₃/CuFeO₂ solar cells demonstrate comparable photovoltaic performance to those using traditional Spiro-OMETAD when the back contact electrode work function exceeds 4.9 eV, and superior performance compared to those with Cu₂O and Spiro-OMETAD at work functions below 4.8 eV. A high acceptor concentration exceeding 10¹⁶ cm⁻³ in CuFeO₂ is recommended to achieve optimal photovoltaic performance. These simulation results highlight the significant potential of employing CuFeO₂ as an HTM layer in CH₃NH₃PbI₃ perovskite-based solar cells as an alternative to the organic Spiro-OMETAD.

Recent Advances and Remaining Challenges in Perovskite Solar Cell Components for Innovative Photovoltaics.

This article reviews the latest advancements in perovskite solar cell (PSC) components for innovative photovoltaic applications. Perovskite materials have emerged as promising candidates for next-generation solar cells due to their exceptional light-absorbing capabilities and facile fabrication processes. However, limitations in their stability, scalability, and efficiency have hindered their widespread adoption. This review systematically explores recent breakthroughs in PSC components, focusing on absorbed layer engineering, electron and hole transport layers, and interface materials. In particular, it discusses novel perovskite compositions, crystal structures, and manufacturing techniques that enhance stability and scalability. Additionally, the review evaluates strategies to improve charge carrier mobility, reduce recombination, and address environmental considerations. Emphasis is placed on scalable manufacturing methods suitable for large-scale integration into existing infrastructure. This comprehensive review thus provides researchers, engineers, and policymakers with the key information needed to motivate the further advancements required for the transformative integration of PSCs into global energy production.

Triple-junction Dion–Jacobson perovskite tandem solar cells: advancing efficiency via interface optimization and broadened light absorption spectrum

Abstract Dion-Jacobson (DJ) perovskites have emerged as game-changers in the world of photovoltaics due to their unique combination of advantages like cost-effective fabrication, tailorable bandgap, and exceptional efficiency. Further, in this study, MXene contacts have been utilized with 2D-perovskites solar cells to leverage the advantages of both, leading to improved stability, superior charge transport, and adjustable energy bandgap without the occurrence of pinhole effects. To further tap into the immense potential of perovskites, this study explores the power of a triple-junction All DJ perovskite tandem solar cell (ADJT-PSC) architecture. This design captures a broader spectrum of sunlight, maximizing energy harvesting and unlocking new possibilities for photovoltaic devices. In this symphony of light and power, 1.5-pentamethylenediamine (PeDA) methylammonium lead iodide (PeDAMAPb2I7) (1.98 eV), PeDAMA5Pb6I19 (1.6 eV), CsLaTa2Se7 (1.1 eV) take as the absorber layers in the top, middle, and bottom subcells, respectively. Moreover, optimizing the thickness of each perovskite layer is crucial for maximizing efficiency. This study conducted a thorough analysis and identified the ideal 350 nm/550 nm/200 nm thicknesses for the top/middle/bottom layers, respectively. Furthermore, the study explored the art of doping variation in the electron and hole transport layers. By meticulously adjusting the doping levels, ADJT-PSC can achieve a maximum efficiency of 35%.

Plasmonic enhanced OLED efficiency upon silver-polyoxometalate core-shell nanoparticle integration into the hole injection/transport layer

Although organic light-emitting diodes (OLEDs) are considered a mature technology, further enhancements in their efficiency are of paramount importance for advancing their incorporation in high-quality displays and flexible, wearable, electronic devices. In this regard, we propose an innovative approach, focusing on strategic modifications to the hole transport layer (HTL) through the integration of core-shell nanoparticles. Silver nanoparticles (Ag-NPs) encapsulated in a tungsten polyoxometalate compound (POM) are embedded within the prototype poly(3,4-ethylenedioxythiophene)-poly(styrenesulphonate) (PEDOT:PSS) to form the modified HTL. Our work reveals the pivotal plasmonic role of Ag-NPs in enhancing OLED device performance based on commercially available conjugated polymers. Comprehensive analyses, including UV–Vis absorption spectroscopy, atomic force microscopy, photoluminescence spectroscopy, and electrical measurements, confirm the influence of the POM encapsulated Ag-NPs on improving the device efficiency. This is attributed to the synergistic influence of enhanced hole injection and conductivity and beneficial optical effects (i.e. the Localized Surface Plasmon Resonance (LSPR) and, likely, light scattering of the POM-Ag NPs in the core-shell configuration, depending on their diameter), contributing to enhanced carrier balance and exciton recombination rate. Comparison with POM gold NPs (POM-Au NPs) highlights the distinct advantages of POM-Ag NPs. Our work reveals the potential of this innovative approach to contribute to the evolution of high-performance OLEDs, ensuring a visually compelling and efficient future.

Exploring Sb2S3 as a hole transport layer for GeSe based solar cell: a numerical simulation

Abstract Germanium selenide (GeSe) and antimony sulfide (Sb2S3) both are technological intriguing semiconductor material for green and economical photovoltaic devices. In this study, GeSe and Sb2S3 have been utilized as the absorber layer and hole transport layer, respectively, to constructed a heterojunction thin film solar cell consisting of FTO/TiO2/GeSe/Sb2S3/Metal. The GeSe and Sb2S3 are binary compounds and can adopt the same film deposition method, for instance, thermal evaporation, which is expected to improve process compatibility and to reduce production costs. The TiO2 (electron transport layer) and Sb2S3 can form small spike-like conduction band offset and valence band offset with the GeSe, respectively, which possesses potential to suppress carrier recombination at the heterointerfaces. Subsequently, the effects of main functional layer material parameters, heterointerface characteristics and back contact metal work function on the performance parameters of the proposed solar cell were simulated and analyzed using wxAMPS software. After numerical simulation and optimization, the proposed solar cell can reach an open circuit voltage of 0.872 V, a short circuit current of 40.72 mA·cm−2, a filling factor of 84.16%, and a conversion efficiency of 28.35%. According to the simulation results, it is anticipated that the Sb2S3 can serve as a hole transport layer for GeSe based solar cell and enable device to achieve high efficiency. Simulation analysis also provides some meaningful references for the design and preparation of heterojunction thin film solar cells.

Design and optimization analysis of a lead-free perovskite solar cell based on copper (I) iodide hole transport layer

Design and optimization analysis of a lead-free perovskite solar cell based on copper (I) iodide hole transport layer

Selection of hole transport layers through lattice mismatching using SCAPS-1D

Selection of hole transport layers through lattice mismatching using SCAPS-1D

Novel hole transport materials of pyrogallol-sulfonamide hybrid: synthesis, optical, electrochemical properties and molecular modelling for perovskite solar cells

Sulfonamide derivatives as semiconductor materials for organic optoelectronic devices, including photovoltaic (PV), have received considerable interest. In the present work, the synthesis of novel pyrogallol-sulfonamide derivatives based on a molecular hybridization approach yielded N-((4-((2,3,4-trihydroxyphenyl)diazenyl)phenyl)sulfonyl)acetamide (N-DPSA). The techniques of spectroscopy, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR), and mass spectrum were utilized to identify the structural composition of the synthesized N-DPSA. The new N-DPSA was investigated by Hall-effect measurement to prove the positive charge carrier (hole mobility) with mobility and conductivity of 2.39 × 103 cm2/Vs and 1.76 × 10–1 1/Ω cm, respectively. Consequently, N-DPSA could be proposed as a strong candidate as a p-type semiconductor (hole transport layer (HTL)). The optical energy gap was computed at 2.03 eV, indicating the direct optical transition nature of N-DPSA. The elaborated molecular semiconductor's thermal features, molecular modelling, and electronic energy levels were also investigated. The new N-DPSA at various concentrations provided easy synthesis, cheap cost, high performance, and a straightforward design approach for a possible HTL in effective perovskite solar cells (PSCs). A PCE of 7.3% is shown for the N-DPSA-based PSC at its optimal concentration.

Low-frequency noise of MoTe2 transistor: effects on ambipolar carrier transport and CYTOP doping

Low-frequency noise (LFN) characteristics of semiconductor devices pose a significant importance for understanding their working principle, particularly concerning material imperfections. Accordingly, substantial research endeavors have focused on characterizing the LFN of devices. However, the LFN characteristics of the ambipolar transistors have been rarely demonstrated. Herein, we investigate the effects of ambipolar carrier transport and CYTOP-induced p-type doping on low-frequency noise characteristics of MoTe2 transistors. The source of the 1/f noise differs between the n-type (electron transport) and p-type (hole transport) modes. Notably, the influence of contact resistance is more pronounced in the n-type mode. CYTOP doping suppresses the n-type mode by introducing hole doping effects. Furthermore, CYTOP doping mitigates the impact of contact resistance on excess noise.

Computational Studies of the Optoelectronic and Charge Transport Properties of Porphyrin and Corrole‐Based Molecules

ABSTRACTThe structural, optoelectronic and charge transport properties of porphyrin and its analogues are investigated using the density functional theoretical methods. Most of the above molecules absorb in visible region with high light harvesting efficiency. The small energy gap between the frontier molecular orbitals (FMOs) suggests that porphyrin and its derivatives can be used in organic semiconductors. Electronic properties such as ionization potential, electron affinity, reorganization energy and the charge transfer integral are calculated to obtain their charge transport properties. It is revealed that porphyrin, porphyrazine and phthalocyanine act as hole transporters, whereas corrole and corrolazine act as electron transporters.

Design and simulation of strong cesium copper–bismuth chloride double perovskite solar cells with an efficiency exceeding 25% for plateau areas

Plateau regions are known for their strong ultraviolet radiation and extended sunlight hours, making them ideal settings for the photovoltaic industry. The development of efficient lead-free perovskite solar cells suitable for high-altitude environments is critical because of the harmful effects of ultraviolet radiation and the toxicity of lead. The cesium copper–bismuth chloride double perovskite with an indirect band gap of 1.36 eV and low toxicity can serve as an ideal absorber for high-efficiency solar cells for ultraviolet and visible absorption. Both density functional theory and a solar cell capacitance simulator were employed to calculate the photoelectric properties of cesium copper–bismuth chloride and optimize device performance. The ideal layer thicknesses of 450 nm for the electron transport layer, 600 nm for the perovskite layer, and 30 nm for the hole transport layer, with respective carrier densities of 1019, 1017, and 1018 cm−3, enabled the optimal device to achieve a short-circuit current of 34.31 mA/cm2, an open-circuit voltage of 0.88 V, a fill factor of 85.3 %, and a power conversion efficiency of 25.62 %, maintaining a fill factor of > 80 % and a power conversion efficiency of > 20 % even at 400 K. Optimized parameters of the absorber and carrier transport layer amplify the built-in electric field and reduce carrier recombination, thereby improving device performance. These findings demonstrate cesium copper-bismuth chloride perovskite solar cells significantly enhance solar energy use in high-altitude environments, providing guidance for the development of other solar cells.

Enhancing Durability of Organic–Inorganic Hybrid Perovskite Solar Cells in High‐Temperature Environments: Exploring Thermal Stability, Molecular Structures, and AI Applications

AbstractThe commercialization of perovskite solar cells (PSCs), as an emerging industry, still faces competition from other renewable energy technologies in the market. It is essential to ensure that PSCs are durable and stable in high‐temperature environments in order to meet the varied market demands of hot regions or seasons. The influence of high temperatures on the PSCs is complex, encompassing factors such as lattice strain, crystal phase changes, the creation of defects, and ion movement. Furthermore, it intensifies lattice vibrations and phonon scattering, which in turn impacts the migration rate of charge carriers. This review focuses on the durability of organic–inorganic hybrid PSCs under high temperatures. It begins by analyzing the impact of external temperature variations on the internal energy dynamics of PSCs. Subsequently, it outlines the various mechanisms provided by different functional molecules, applied to interface stabilization, grain boundary passivation, crystal growth control, electrode protection, and the development of new hole transport layers, to enhance the thermal stability of PSCs. Additionally, machine learning (ML) is discussed for predicting crystal structure stability, PSCs operational stability, and material screening, with a focus on the potential of deep learning and explainable artifical intelligence (AI) techniques in the commercialization of PSCs.

Fine-Tuning Conformation of PEDOT Chains Enables Simultaneously Enhanced Conductivity, Work Function, Transmittance, and Waterproofness in PEDOT:PSS Interlayer for Highly Efficient and Stable Organic Photovoltaics.

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is widely utilized as the hole transport layer (HTL) inorganic photovoltaics (OPVs) because of its low-temperature solution processing peculiarity, high optical transmittance, and excellent mechanical flexibility. However, the core-shell structure of PSS coated PEDOT results in relatively low conductivity, work function, transmittance and waterproofness of PEDOT:PSS interlayer, limiting the photovoltaic performance and stability of OPVs. Here, the conformation of PEDOT chains are regulated from helical benzoyl to linear quinone structure via incorporation of 2D Cd0.85PS3Li0.15H0.15dopant into the conventional PEDOT:PSS interlayer, promoting an interpenetrating network structure in PEDOT:PSS interlayer and forming an efficient hole transport channel from active layer to ITO electrode. Such features significantly improve the electrical conductivity, work function, and transmittance of PEDOT:PSS interlayer. In consequence, the maximum power conversion efficiency (PCE) of D18:L8-BO, PBDB-T:ITIC, as well as PTzBI-dF:L8-BO based OPVs ameliorated from 18.37%, 8.94%, and 15.80% to 19.26%, 10.00%, and 16.83%, respectively. The application of Cd0.85PS3Li0.15H0.15 doping PEDOT:PSS strategy demonstrates great potential for the development of strongly conductive, large-work-function, highly transparent, and excellent-waterproof PEDOT:PSS interlayer toward highly efficient and stable OPVs.