Electron Transport Layer Material Research Articles

Design and optimization of Cs2SnI6 based inorganic perovskite solar cell model: numerical simulation

To overcome the drawbacks of high lead toxicity and poor corrosion resistance of lead-based perovskite solar cells (PSCs), and to compensate for the poor air stability of Sn2+ compound-based perovskite, Cs2SnI6 (Sn4+ compound) is selected as the absorber for the PSC in this study. Using FTO/ETL/Cs2SnI6/HTL/Au as the model, the high-performance non-toxic inorganic PSC structure is explored through theoretical simulation and calculation by SCAPS-1D. The conduction band offsets (CBO) and valence band offsets (VBO) of commonly used electron transport layer materials (ETMs), hole transport layer materials (HTMs), and Cs2SnI6 are calculated based on electron affinity potential (χ) and bandgap (E g ). Then, by analyzing the pn junction composed of ETL and HTL and the bandgap structure at the n-i, i-p interfaces, the most matching n-i-p planar heterojunction model, FTO/IGZO/Cs2SnI6/Cu2BaSnS4/Au, was selected. Finally, by analyzing and adjusting the material thickness, defect density of each layer, operation temperature, the optimal performance of PSC was determined to be 30.39% power conversion efficiency (PCE), 1.27 V open circuit voltage (V oc ), 28.46 mA cm−2 short circuit current (J sc ), and 84.02% fill factor (FF). A new and more efficient PSC is proposed in this study, providing some terrific clues for finding high-quality alternatives to lead-based PSCs.

Guanidine carbonate modified TiO2/Perovskite interface for efficient and stable planar perovskite solar cells

The rational design and modification of the buried interface are essential and challenging for high-performance perovskite solar cells (PSCs). TiO2 is a simple and readily available electron transport layer material, but its surface defects and poor interfacial contact with perovskite layers hinder its widespread application. Here, we propose an effective TiO2/perovskite interface modification strategy by introducing simple guanidine carbonate (GuaCO3) onto the surface of TiO2. Guanidine carbonate can improve the interfacial contact between TiO2 and perovskite, reduce non-radiative recombination, and enhance carrier extraction. Moreover, the PbI2 film grown on the TiO2/GuaCO3 substrate tended to become porous during the preparation of perovskite films by the traditional two-step method, which facilitated the complete reaction of organic ammonium salts with PbI2 and promoted the growth of high-quality perovskite films. The experimental results indicate that GuaCO3 can passivate the interfacial defects of TiO2/perovskite, as well as reduce the accumulation of interfacial charges. The device modified with GuaCO3 achieved a power conversion efficiency (PCE) of 23.39 %, which is significantly higher than that of the control device (21.73 %). After storage in an ambient environment at room temperature for 600 h, the unencapsulated device modified with GuaCO3 retained 78 % of its initial efficiency, while the control device retained only 57 % of its initial efficiency. These results indicate that interfacial modification with GuaCO3 is an effective strategy for improving the performance of PSCs.

Improvement of Photovoltaic Performance of Perovskite Solar Cells by Synergistic Modulation of SnO2 and Perovskite via Interfacial Modification.

In the past decade, perovskite solar cell (PSC) photoelectric conversion efficiency has advanced significantly, and tin dioxide (SnO2) has been extensively used as the electron transport layer (ETL). Due to its high electron mobility, strong chemical stability, energy level matching with perovskite, and easy low-temperature fabrication, SnO2 is one of the most effective ETL materials. However, the SnO2 material as an ETL has its limitations. For example, SnO2 films prepared by low-temperature spin-coating contain a large number of oxygen vacancies, resulting in energy loss and high open-circuit voltage (VOC) loss. In addition, the crystal quality of perovskites is closely related to the substrate, and the disordered crystal orientation will lead to ion migration, resulting in a large number of uncoordinated Pb2+ defects. Therefore, interface optimization is essential to improve the efficiency and stability of the PSC. In this work, 2-(5-chloro-2-benzotriazolyl)-6-tert-butyl-p-cresol (CBTBC) was introduced for ETL modification. On the one hand, the hydroxyl group of CBTBC forms a Lewis mixture with the Sn atom, which reduces the oxygen vacancy defect and prevents nonradiative recombination. On the other hand, the SnO2/CBTBC interface can effectively improve the crystal orientation of perovskite by influencing the crystallization kinetics of perovskite, and the nitrogen element in CBTBC can effectively passivate the uncoordinated Pb2+ defects at the SnO2/perovskite interface. Finally, the prevailing PCE of PSC (1.68 eV) modified by CBTBC was 20.34% (VOC = 1.214 V, JSC = 20.49 mA/cm2, FF = 82.49%).

Abnormal temperature-dependent transient electroluminescence spikes induced by the leakage of hole carriers in organic light-emitting diodes

The amplitude of the emission spike at the transient electroluminescence (TEL) falling edge is an important benchmark for evaluating the quantities of trapped charges existed in organic light-emitting diodes and often shows a normal temperature dependence which increases with the decreasing temperature. Surprisingly, an unreported abnormal temperature-dependent TEL spike was observed in this work. A series of experimental results relevant to the electroluminescence spectrum and TEL measurements demonstrate that this abnormal temperature-dependent behavior is induced by the leakage of hole carriers from the emission layer (EML) to an electron transport layer (ETL). After the voltage pulse is turned off, these holes already leaked into the ETL drift back toward the EML, subsequently engaging in radiative recombination with trapped electrons on guest molecules to generate a spike at the TEL falling edge. However, the drift process is hindered by the reduced carrier mobility of the ETL material with the decrease in temperature. As a result, the spike intensity weakens as the temperature decreases, which contradicts the conclusions reported in previous literatures. Therefore, this study not only leads to the reconsideration for the judgment criteria of the number of trapped charges but also provides valuable insight into the TEL research field of organic optoelectronic devices.

A numerical approach to optimize the performance of HTL-free carbon electrode-based perovskite solar cells using organic ETLs

Carbon electrode-based perovskite solar cells (c-PSCs) without a hole transport layer (HTL) have obtained a significant interest owing to their cost-effective, stable, and simplified structure. However, their application is limited by low efficiency and the prevalence of high-temperature processed electron transport layer (ETL), e.g. TiO2, which also has poor optoelectronic properties, including low conductivity and mobility. In this study, a series of organic materials, namely PCBM ((Park et al., 2023; Park et al., 2023) [6,6]-phenyl-C61-butyric acid methyl ester, C72H14O2), Alq3 (Al(C9H6NO)3), BCP (2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline, C26H20N2), C60, ICBA (indene-C60 bisadduct, C78H16) and PEIE (poly (ethylenimine) ethoxylated, (C37H24O6N2)n) have been numerically analyzed in SCAPS-1D solar simulator to explore alternative potential ETL materials for HTL-free c-PSCs. The presented device has FTO/ETL/CH3NH3PbI3/carbon structure, and its performance is optimized based on significant design parameters. The highest achieved PCEs for PCBM, Alq3, BCP, C60, ICBA, and PEIE-based devices are 22.85%, 19.08%, 20.99%, 25.51%, 23.91%, and 22.53%, respectively. These PCEs are obtained for optimum absorber thickness for each case, with an acceptor concentration of 1.0 × 1017 cm−3 and defect density of 2.5 × 1013 cm−3. The C60-based cell has been found to outperform with device parameters as Voc of 1.29 V, Jsc of 23.76 mA/cm2, and FF of 82.67%. As the design lacks stability when only organic materials are employed, each of the presented devices have been analyzed by applying BiI3, LiF, and ZnO as protective layers with the performances not compromised. We believe that our obtained results will be of great interest in developing stable and efficient HTL-free c-PSCs.

Design and optimization of high-performance eco-friendly perovskite solar cells: Utilizing FAMASnGeI3 and CsGeI3 as absorbers and tuning HTL and interface parameters

In this work, several designs of lead-based and lead-free perovskite solar cells (PSCs) have been developed and investigated. For the proposed designs, CH3NH3PbI3 (lead-based), FAMASnGeI3, and CsGeI3 (lead-free) are used as absorber materials, [Formula: see text] and NiO have been used as Hole Transport Layer (HTL) materials and TiO2 as Electron Transport Layer (ETL) materials. ETL materials, in general, have more concern with stability issues and HTL materials have more issues with efficiency improvements. The effect of changing thickness, doping density and defect density of the absorber layer, as well as HTL, defect density of absorber/HTL interface and work functions of front and back contacts on the performance of the proposed devices, are investigated. To enhance the device performance, optimization of the device parameters is performed. After optimization of different parameters, it is observed that the lead-based device structure TiO2/CH3NH3PbI3/NiO has a maximum efficiency of 29.94%. Even the corresponding lead-free device structure TiO2/CsGeI3/NiO exhibits a maximum efficiency of 29.19%. Additionally, this study delved into the influence of altering series and shunt resistances, as well as temperature on the operational characteristics of the lead-free optimized device. Such eco-friendly and cost-effective alternatives as lead-free perovskite cells can be very promising for future work.

High‐Performance Perovskite Solar Cells with Zwitterion‐Capped‐ZnO Quantum Dots as Electron Transport Layer and NH4X (X = F, Cl, Br) Assisted Interfacial Engineering

The systematic advances in the power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs) have been driven by the developments of perovskite materials, electron transport layer (ETL) materials, and interfacial passivation between the relevant layers. While zinc oxide (ZnO) is a promising ETL in thin film photovoltaics, it is still highly desirable to develop novel synthetic methods that allow both fine‐tuning the versatility of ZnO nanomaterials and improving the ZnO/perovskite interface. Among various inorganic and organic additives, zwitterions have been effectively utilized to passivate the perovskite films. In this vein, we develop novel, well‐characterized betaine‐coated ZnO QDs and use them as an ETL in the planar n‐i‐p PSC architecture, combining the ZnO QDs‐based ETL with the ZnO/perovskite interface passivation by a series of ammonium halides (NH4X, where X = F, Cl, Br). The champion device with the NH4F passivation achieves one of the highest performances reported for ZnO‐based PSCs, exhibiting a maximum PCE of ~22% with a high fill factor of 80.3% and competitive stability, retaining ~78% of its initial PCE under 1 Sun illumination with maximum power tracking for 250 h.

Choline Derivative as a Multifunctional Interfacial Bridge through Synergistic Effects for Improving the Efficiency and Stability of Perovskite Solar Cells.

The interfacial carrier non-radiative recombination caused by buried defects in electron transport layer (ETL) material and the energy barrier severely hinders further improvement in efficiency and stability of perovskite solar cells (PSCs). In this study, the effect of the SnO2 ETL doped with choline chloride (CC), acetylcholine chloride (AC), and phosphocholine chloride sodium salt (PCSS) are investigated. These dopants modify the interface between SnO2 ETL and perovskite layer, acting as a bridge through synergistic effects to form uniform ETL films, enhance the interface contact, and passivate defects. Ultimately, compared with CC (which with ─OH) and AC (which with C═O), the PCSS with P═O and sodium ions groups is more beneficial for improving performance. The device based on PCSS-doped SnO2 ETL achieves an efficiency of 23.06% with a high VOC of 1.2V, which is considerably higher than the control device (20.55%). Moreover, after aging for 500h at a temperature of 25°C and relative humidity (RH) of 30-40%, the unsealed device based on SnO2 -PCSS ETL maintains 94% of its initial efficiency, while the control device only 80%. This study provides a meaningful reference for the design and selection of ideal pre-buried additive molecules.

Numerical simulation and performance optimization of a lead-free inorganic perovskite solar cell using SCAPS-1D

The perovskite solar cells, founded on lead halides, have garnered significant attention from the photovoltaic industry owing to their superior efficiency, ease of production, lightweight characteristics, and affordability. However, due to the hazardous nature of lead-based compounds, these solar cells are currently unsuitable for commercial production. In this context, a lead-free perovskite, cesium-bismuth iodide (Cs3Bi2I9) is considered as a potential alternative to the lead halide-based cell due to their non-toxicity and stability, but this perovskite cannot be matched with random hole transport layer (HTL) and electron transport layer (ETL) materials compared to lead halide-based perovskite because of their crystal structure and band gap. Therefore, in this study, performance comparison of different ideal HTL and ETL materials for Cs3Bi2I9 perovskite layer were studied using SCAPS-1D device simulation on the basis of open circuit voltage, short circuit current, power conversion efficiency (PCE) and fill factor (FF) as well as several novel PSC configuration models were designed that can direct for further experimental research for PSC device commercialization. Results from this investigation reveals that the maximum efficiency of 20.96 % is obtained for the configuration ITO/WS2/Cs3Bi2I9/NiO/Au with optimized parameters such as thickness 400 nm, band gap 2.1eV, absorber layer defect density 1012 cm−3, donor density of ETL 1018 cm−3 and the acceptor density of HTL 1020 cm−3.

Design and performance evaluation of eco-friendly FASnI3/CsSn0.5Ge0.5I3 based perovskite solar cell with distinct charge transport layer: A computational modeling

This article provides a comprehensive analysis and exploration of a novel design approach for Perovskite Solar cells (PVKSC) that incorporates two absorber layers, with a specific focus on their potential applications in energy generation. This research employs a computational modeling approach to conduct a thorough examination of PVKSCs based on FASnI3/CsSn0.5Ge0.5I3. The primary objective of this study is to examine and choose the appropriate materials for the hole transport layer material (HTLM) and the electron transport layer material (ETLM). Additionally, the research aims to identify the optimal parameters for the active thickness layer, trap concentration, energy bandgap, interface trap concentration, and acceptor concentration for PVKSC. Through the optimization of the device's parameters, notable improvements are observed. The power conversion efficiency (PCE) is enhanced to 33.16 %, while the current density (Jsc) experiences an increase to 31.218 mA/cm2. Additionally, the open circuit voltage rises to 1.185 V, and the fill factor demonstrates improvement, reaching 89.58 %. These advancements are achieved by employing Zn3P2 as the HTLM and SnS2 as the ETLM in the design. This research emphasizes the optimistic prospects of lead-free PVKSC and presents novel opportunities for their advancement and utilization in diverse solar contexts.

SCAPS-1D Modeling of Hydrogenated Lead-Free Cs2AgBiBr6 Double Perovskite Solar Cells with a Remarkable Efficiency of 26.3.

In this investigation, we employ a numerical simulation approach to model a hydrogenated lead-free Cs2AgBiBr6 double perovskite solar cell with a p-i-n inverted structure, utilizing SCAPS-1D. Contrary to traditional lead-based perovskite solar cells, the Cs2AgBiBr6 double perovskite exhibits reduced toxicity and enhanced stability, boasting a maximum power conversion efficiency of 6.37%. Given its potential for improved environmental compatibility, achieving higher efficiency is imperative for its practical implementation in solar cells. This paper offers a comprehensive quantitative analysis of the hydrogenated lead-free Cs2AgBiBr6 double perovskite solar cell, aiming to optimize its structural parameters. Our exploration involves an in-depth investigation of various electron transport layer materials to augment efficiency. Variables that affect the photovoltaic efficiency of the perovskite solar cell are closely examined, including the absorber layer's thickness and doping concentration, the hole transport layer, and the absorber defect density. We also investigate the impact of the doping concentration of the electron transport layer and the energy level alignment between the absorber and the interface on the photovoltaic output of the cell. After careful consideration, zinc oxide is chosen to serve as the electron transport layer. This optimized configuration surpasses the original structure by over four times, resulting in an impressive power conversion efficiency of 26.3%, an open-circuit voltage of 1.278 V, a fill factor of 88.21%, and a short-circuit current density of 23.30 mA.cm-2. This study highlights the critical role that numerical simulations play in improving the chances of commercializing Cs2AgBiBr6 double perovskite solar cells through increased structural optimization and efficiency.

Pressure and temperature effects on the electron transport layer material for solar energy applications: a molecular dynamic approach explores the influence of environmental conditions of biostructure materials in solar cells

This investigation initiated by modelling the crystal structure of perovskite to explore the impact of different temperatures. Researchers modified the perovskite crystal structure and observed its response to temperature variations. The study involved assessing the efficiency and fill factor of perovskite solar cells, incorporating photovoltaic structures without specifying the electron transport layer material. The primary goal of this initiative is to provide power to buildings using environmentally acceptable components in perovskite solar cells. The promising efficiency and cost-effectiveness of manufacturing make perovskite solar cells an intriguing option for generating clean and sustainable energy.

Aqueous solution processed electron-transporting layer based on organosilica nanodots for highly efficient and stable inverted organic solar cells

In this work, we synthesis a new electron-transporting layer material for inverted organic solar cells(i-OSCs) based on organosilica nanodots. The material is synthesized by a simple one-step hydrothermal reaction of 3-[2-(2-aminoethylamino)ethylamino] propyl-trimethoxysilane (AEEA) with carminic acid in water solvent (OSi-CA). Compared with ZnO-based devices, OSi-CA based devices show improved carrier extraction, higher PCE, and greatly increased device stability under UV irradiation. With PM6:Y6 as the active layer, OSi-CA based device has a PCE of 16.01 %. In addition, the OSi-CA electron-transporting layer significantly improves the photostability of OSCs. After 600 min of continuous UV lamp (5 mW cm−2) irradiation, the OSi-CA based i-OSC retained 95.5 % of its initial performance, whereas the ZnO-based device had only 71.2 %.

Metallaaromatic Complexes as Candidates for Future Molecular Materials and Electronic Devices: Recent Advancements.

In recent years, the field of organometallic chemistry has made a great progress and diverse types of metallaaromatics have successively been reported. In those studies, incorporation of ligated osmium centers into metallaaromatic systems played a prominent role. The reviewed literature documents that certain metallaaromatics with unconventional photophysical properties, redox and electronic transport properties and magnetism, have potential to be widely used in diverse practical applications, with selected examples of amino acid and fluoride anion identification, photothermal effects, functional materials, photodynamic therapy (PDT) in biomedicine, single-molecule junction conductors, and electron-transport layer materials (ETLs) in solar cells.

Synthesis and characterization of TiO2-graphene heterostructured quantum dots by electrochemical process

Titanium dioxide (TiO2) is a trendily attractive semiconductor owing to its optical and electrical properties within the UV-visible range. Nevertheless, limitations such as instability in the UV range and rapid recombination of photogenerated charge carriers leading to poor efficiency in photoactivity are major limiting factors that hold back the application of the materials on large scale. In order to tackle the stated issues, graphene quantum dots (GQDs), with their high carrier conductivity, UV-stability and thermal conductivity, can be used to improve TiO2’s flaws as optoelectronic materials. As a suitable edge transporter and modifier, GQDs can be grown as heterostructure well-bonded with TiO2 quantum dots. This material modification can lead to combined benefits of using TiO2 QDs’ preferable optoelectronic properties in UV-visible range and GQDs’ high conductivity and stability. This allows the synthesis of heterostructured quantum dots that can be tailored towards wide range of applications such as electron transport layer materials in perovskite solar cells or highly stable colloidal-based photocatalysts. In this study, TiO2/GQDs nanocomposites were synthesized using a solution-based electrochemical process with citric acid and potassium chloride (KCl) acting as electrolytes. Our proposed recipe yielded heterostructured QDs with average size of 3.44 nm well below the exciton Bohr radius of both TiO2 and graphene and hydrodynamic sizes around 45-59 nm with zeta potential in range of -24 to 30 mV. This yielded colloidal solution with stability and surface ion tunability based on KCl concentration with 0.3 M being the most stable recipe. Additionally, absorption band edge can also be tuned within the range of 2.8-3.9 eV which can be adjusted with concentration of KCl based on the desired applications.

Designing next-generation kesterite solar cells: A systematic numerical investigation of innovative structures and design variants for enhanced photovoltaic performance

This paper presents a thorough numerical investigation of copper zinc tin sulfide (CZTS)-based solar cells utilizing the SCAPS-1D simulation tool. In light of the scarcity of indium and gallium, CZTS is explored as a promising alternative absorber material. The study encompasses an extensive array of 280 device simulations, including a systematic optimization process targeting enhanced power conversion efficiency (PCE). Notably, this iterative optimization procedure results in a notable PCE increase from 11.01% to 14.24%. By delving into the realm of electron transport layer (ETL) materials, the integration of a CdO layer culminates in a significant PCE milestone of 15.71%, and a new structure was extrapolated from this step Back contact/CZTS/CdO/ZnO. Furthermore, an exploration involving 172 diverse configurations incorporating various hole transport layer (HTL) materials unveils a remarkable peak PCE of 21.14% (Back contact/SnS/CZTS/CdSe/ZnO). These findings provide valuable insights and directives for the advancement and optimization of CZTS-based solar cells.

High-performance inkjet-printed inverted QD-LEDs based on cross-linkable electron regulation layers

In all-solution-processed quantum dot light-emitting diodes (QD-LEDs), zinc oxide nanoparticles (ZnO NPs) have been one of the most widely used electron transport layer materials. However, the high electron mobility and abundant surface defects of ZnO NPs usually entail not only charge imbalance in the QDs, but also exciton quenching at the QDs/ZnO interface. To overcome the shortcomings, a strategy is proposed by employing cross-linkable organics (isomeric TV-TmPY or TV-T2T) as an electron regulation layer (ERL) in inverted QD-LEDs. The spin-coated RGB QD-LEDs with TV-T2T inserts exhibit less sensitivity to interlayer thickness and great performance enhancements, with EQEs up to 20.2% for the red devices, 15.3% for the green devices, and 9.1% for the blue devices. The inkjet-printed RGB QD-LEDs with TV-T2T inserts also achieve EQEs of 18.4%, 13.3%, and 5.6%, respectively, representing the highest reported performance for inkjet-printed inverted QD-LEDs to date.

Highly conducting Al-doped zinc oxide electron transport layer for all-inorganic perovskite solar cells: An experimental and simulation study

The need for an excellent electron transport layer (ETL) material is immensely significant for higher conversion efficiency of perovskite solar cells (PSCs). This work centers on the exceptional performance achieved by the Al-doped ZnO (AZO) ETL with reference to undoped ZnO (ZnO). Both doped and undoped ETL materials were synthesized and characterized to determine their structural, morphological, and optical behavior. In this work, solar cell performance of two similar CsPbIBr2-based PSCs with different ETLs namely FTO/ZnO/CsPbIBr2/NiO (Cell #1) and FTO/AZO/CsPbIBr2/NiO (Cell #2) are investigated through numerical simulation method. The obtained characteristics affirms that Cell #2 offers sufficient better performance parameters (Jsc, Voc, FF, and η) against Cell #1 with respect to variation in CsPbIBr2 PVT, ETL and HTL thickness. The adverse effect on J-V characteristics caused by controllable introduction of defect density (Nt) in PVT layer is negligible for Cell #2 compared to its ZnO counterpart. Further, the contribution of AZO ETL layer on cell's performance is evaluated in terms of variation in respective ETL and HTL thickness. The investigation reveals that Cell #2 offers a desirable η of 19.46% at electron capture cross section of 2 × 10−15 cm2 while Cell #1 delivers only 12.48%.

Properties Evaluation of PPY-CuO Incorporated GO as Electron Transporting Layer Material for OLED Application

Properties Evaluation of PPY-CuO Incorporated GO as Electron Transporting Layer Material for OLED Application

Enriched properties of polypyrrole-copper oxide-reduced graphene oxide (PPY-CuO-rGO) hybrid nanocomposite for organic light emitting diodes (OLEDs) as electron transport layer (ETL) material

Enriched properties of polypyrrole-copper oxide-reduced graphene oxide (PPY-CuO-rGO) hybrid nanocomposite for organic light emitting diodes (OLEDs) as electron transport layer (ETL) material