Phenyl C61-butyric Acid Methyl Research Articles

The role of TCNQ for surface and interface passivation in inverted perovskite solar cells

The noticeable growth in the power conversion efficiency of solution-processed organo-inorganic halide perovskite solar cells (OIHPSCs) incited the photovoltaic community to look for limitations that hurdle the commercialization process. The surface and interface defects between the perovskite and electron transport layers are among the main challenges that cause significant non-radiative recombination losses, thereby they result in poor performance and stability. In this work, tetracyanoquinodimethane (TCNQ), a strong electron acceptor molecule, is applied at the interface between the photoactive perovskite and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) layers to modify the interface, and enhance device performance and stability. Steady-state and time-resolved photoluminescence measurements were used to characterize the role of the TCNQ passivation in reducing non-radiative recombination of charge carriers. Current density versus voltage (J-V) measurements show improvement in devices open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF) for devices with TCNQ interface passivation, which is attributed to suppressed non-radiative recombination. In addition, a noticeable improvement in the device’s stability was observed. This study reveals the dual role of TCNQ passivation in improving the photoelectric properties and stability of ambient air processed perovskite devices with the pin architecture.

PCBM Constructing Heterojunction for Efficient CsPbI3 Perovskite Quantum Dot Solar Cells.

CsPbI3 perovskite quantum dots (PQDs) have emerged as promising photovoltaic materials for third-generation solar cells, owing to their superior optoelectronic properties. Nevertheless, the performance of CsPbI3 PQD solar cells is primarily hindered by low carrier extraction efficiency, largely due to the insulative ligands. In this study, we introduced a semiconductor molecule, [6,6]-phenyl C61 butyric acid methyl ester (PCBM), onto the surfaces of CsPbI3 PQDs as surface ligands to enhance photogenerated charge extraction. The results indicate that PCBM accelerates carrier separation in CsPbI3 PQDs by forming a type II heterojunction, and also modulates the energy level of CsPbI3 PQDs by altering surface dipole moments. Additionally, we established an energy-level gradient alignment in the PCBM/CsPbI3 PQD heterojunction absorber layer, which was found to effectively promote carrier extraction and reduce carrier recombination loss in PQD solar cells. Ultimately, the PQD solar cells incorporating this novel structure achieved a power conversion efficiency of 14.23%, a significant improvement compared to 12.69% achieved by solar cells with a traditional structure, thus demonstrating the strong potential of this approach for high-performance PQD solar cells.

Elucidating the hysteresis effect in printed flexible perovskite solar cells with SnO2 quantum dot- and PCBM-based electron transport layers

Recently, flexible perovskite solar cells (FPSCs) fabricated using solution-processed printing techniques have garnered significant attention. However, challenges remain in achieving cost-effective, scalable manufacturing under ambient conditions and ensuring stable, efficient devices. This study focuses on fabricating printed FPSCs using the slot-die coating technique and examines the impact of SnO2 quantum dot (QD) and (6,6)-Phenyl C61 butyric acid methyl ester (PCBM) based electron transport layers (ETLs) on device performance and hysteresis. Experimentally results show that SnO2 QD-based devices exhibited favorable photovoltaic properties but significant hysteresis compared to PCBM-based devices. Numerical simulations have shown that the hysteresis effect in devices is influenced not only by the higher concentration of mobile ions in the perovskite layer of PCBM-based devices compared to SnO2 QD-based devices, but also by the more effective redistribution of these ions during forward and reverse J-V scans. The results provide insights into the behavior of printed FPSCs with different ETLs, contributing to the development of high-performance, hysteresis-free printed FPSCs.

Unveiling Nanoscale Ordering in Amorphous Semiconducting Polymers Using Four-Dimensional Scanning Transmission Electron Microscopy.

We present four-dimensional (4D) scanning transmission electron microscopy (STEM) analysis to obtain a high level of detail regarding the nanoscale ordering within largely disordered organic semiconducting polymers. Understanding nanoscale molecular ordering in semiconducting polymers is crucial due to its connection to the materials' important properties. However, acquiring such information in a spatially localized manner has been limited by the lack of a nanoscale experimental probe, weak signal from ordering, and radiation damage to the sample. By collecting nanodiffraction patterns with a high dynamic range pixelated detector, we acquired statistically robust, high signal-to-noise ratio diffraction patterns from semiconducting organic materials, including poly(3-hexylthiophene-2,5-diyl) (P3HT), P3HT/[6,6]-phenyl C61 butyric acid methyl ester, and indacenodithiophene-co-benzothiadiazole (IDTBT), which largely have disordered structures. Real-space images of the ordered domains were reconstructed from the 4D-STEM data set for a variety of scattering vectors and in-plane angles to capture the different molecular stacking distances and their in-plane orientation. These were then analyzed to obtain the average size of the ordered domains within the sample. Such measurements were arranged in a two-dimensional (2D) histogram, which showed a direct relationship between the type and size of molecular ordering. Complementary analyses, such as intensity variance and angular correlation, were applied to obtain ordering and symmetry information. These analyses enabled us to directly characterize the alkyl and π-π stacking of P3HT, as well as the fullerene domains caused by donor segregation in the P3HT sample. Furthermore, the analysis also captured changes in the P3HT domains when the fullerenes are incorporated. Lastly, IDTBT showed a much lesser degree of ordering without much disinclination between the domains within the 2D histogram. The 4D-STEM analysis that we report here unveils new details of molecular ordering that can be used to optimize the properties of this important class of materials.

Investigating the influence of Al2O3 doping on TiO2 optoelectronic properties and charge separation efficiency

In this study, Aluminum oxide (Al2O3) was utilized as a dopant in the crystal structure of titanium dioxide (TiO2) to enhance the photovoltaic efficiency of n-i-p type organic solar cells. These solar cells were fabricated using a thin film of TiO2 doped with Al2O3, serving as the electron transport layer. TiO2 thin films were synthesized using different Al2O3 concentrations (0 %, 0.25 %, 0.5 %, and 1 % w/V) through the spin-coating technique. A blend of poly(3-hexylthiophene) and phenyl C61-butyric acid methyl ester (P3HT:PC61BM) was spin-cast at 600 rpm for 30 s, forming the solar cells active layer. Organic solar cells with an n-i-p structure were constructed, following the configuration FTO/TiO2:Al2O3/P3HT:PC61BM/MoO3/Ag. Investigations have been conducted to examine how varying concentrations of Al2O3 doping affect the photovoltaic performance of the solar cells. The power conversion efficiency (PCE) of the produced solar cells showed an increase from 2.74 % to 3.53 % at a 0.5 % Al2O3 doping concentration. The solar cells performance has been improved by adjusting the concentration of Al2O3. The findings show that the addition of Al2O3 to TiO2 films improves power conversion efficiency.

Influence of Aluminum Pillar Nanostructures on Thin‐Film Organic Solar Cells

This study explores the application of pillar nanostructures in organic solar cells (OSCs). The aluminum pillar nanostructures (AlPNSs) are fabricated on an active layer surface comprising of a blend poly(3‐hexylthiophene‐2,5‐diyl) and [6,6]‐phenyl C61 butyric acid methyl ester using nanoimprinting. Aluminum back electrodes are formed, resulting in AlPNSs with an imprinted pattern height of 60 ± 6 nm and a pitch of 212 ± 49 nm. Atomic force microscope images and current density versus voltage curves are obtained for the fabricated devices, both with and without AlPNSs. The results indicate a solar cell efficiency increase of 15.16% in the AlPNS OSCs compared to the reference cells. To investigate the role of AlPNSs in the enhancement, impedance spectroscopy, incident photon‐to‐current efficiency, UV–Vis reflection spectroscopy, and finite‐difference time‐domain simulations are performed for the both devices. The results demonstrate that the combination of propagating surface plasmon resonance and light‐trapping properties due to AlPNSs significantly enhances the overall optical performance. This research provides new insights into the potential of imprinted nanostructures for enhancing OSC performance, including their plasmonic and optical characteristics.

Improving photovoltaic characteristics of CdS-based hybrid solar cells through Mn incorporation

CdS thin films, both with and without Mn-doping, were grown via chemical bath deposition on indium tin oxide-coated glass substrates for application in hybrid solar cells. X-ray diffraction analysis revealed that Mn doping led to a deterioration in the crystal quality of CdS samples, evidenced by increased microstrain and dislocation density. Mn atoms were interstitially incorporated into the CdS structure, resulting in an expansion of the unit cell volume. Morphological analysis indicated a decrease in grain size from 390 nm to 140 nm for 0 % and 2 % Mn-doped CdS samples, respectively, while maintaining the spherical shape of the CdS thin films. Mn doping also increased the transmittance of CdS thin films, with the highest transparency of 95 % at 580 nm achieved for the 2 % Mn-doped CdS sample. In comparison to undoped CdS (2.38 eV), the band gap of CdS samples initially decreased to 1.84 eV for 1 % Mn doping but significantly increased to 3.03 eV for 2 % Mn-doped CdS. Photoluminescence (PL) data indicated that 2 % Mn-doped CdS thin films exhibited the lowest peak intensity, suggesting that a high concentration of Mn atoms caused non-radiative charge recombination. Additionally, efficient exciton dissociation was observed between CdS:Mn and P3HT:PCBM (poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM)) layers in the 2 % Mn-doped CdS-based device, as per the PL results. Photovoltaic measurements demonstrated that compared to undoped CdS, 2 % Mn doping increased the power conversion efficiency of the CdS-based device from 0.070 % to 0.202 %, indicating an almost threefold increase in hybrid solar cell efficiency. This improvement is likely attributed to the development of a better interface between the CdS:Mn and P3HT:PCBM layers.

Interface passivation using diketopyrrolopyrrole‐oligothiophene copolymer to improve the performance of perovskite solar cells

AbstractThe unprecedented increase in power conversion efficiency (PCE) of low‐cost organo‐inorganic halide perovskite solar cells (OIHPSCs) toward its Shockley‐Queisser limit intriguingly has prompted researchers to investigate the disadvantages of these devices. The issue of operational stability is the main hurdle challenging the way forward for commercialization. To address this, various engineering processes like composition, additives, anti‐solvents, bulk and interface passivation, and deposition techniques have been widely applied to manage both extrinsic and intrinsic factors that induce degradation of the OIHPSCs. In this work, we employed interface passivation, which is an efficient approach to reduce nonradiative recombination. An ultrathin layer of electron donor diketopyrrolopyrrole‐oligothiophene copolymer (DPP860) was applied as an interface passivator between the photoactive layer and [6,6]‐phenyl C61 butyric acid methyl ester (PCBM). The role of the interface passivation on optoelectronic properties of the OIHPSCs was assessed using current density versus voltage (J‐V) characteristics, photoluminescence spectroscopy and time‐resolved photoluminescence spectroscopy. The findings show devices treated with DPP860 exhibit enhanced current density (Jsc) and fill factor, attributing for suppressed nonradiative recombination. Moreover, it shows relative improvement in the stability of the device. The results of this finding reveal that using oligothiophene copolymer can enhance the photovoltaic performance and the stability of inverted OIHPSCs in the ambient environment.

Fluorinated organic ammonium salt passivation for high-efficiency and stable inverted CsPbI2Br perovskite solar cells.

All-inorganic CsPbI2Br inverted perovskite solar cells (PSCs) have drawn increasing attention because of their outstanding thermal stability and compatible process with tandem cells. However, relatively low open circuit voltage (Voc) has lagged their progress far behind theoretical limits. Herein, we introduce phenylmethylammonium iodide and 4-trifluoromethyl phenylmethylammonium iodide (CFPMAI) on the surface of a CsPbI2Br perovskite film and investigate their passivation effects. It is found that CFPMAI with a -CF3 substituent significantly decreases the trap density of the perovskite film by forming interactions with the under-coordinated Pb2+ ions and effectively suppresses the non-radiative recombination in the resulting PSC. In addition, CFPMAI surface passivation facilitates the optimization of energy-level alignment at the CsPbI2Br perovskite/[6,6]-phenyl C61 butyric acid methyl ester interface, resulting in improved charge extraction from the perovskite to the charge transport layer. Consequently, the optimized inverted CsPbI2Br device exhibits a markedly improved champion efficiency of 14.43% with a Voc of 1.12V, a Jsc of 16.31 mA/cm2, and a fill factor of 79.02%, compared to the 10.92% (Voc of 0.95V) efficiency of the control device. This study confirms the importance of substituent groups on surface passivation molecules for effective passivation of defects and optimization of energy levels, particularly for Voc improvement.

Effective surface passivation for stable and high-performance inverted CsPbI2Br perovskite solar cells with efficiency over 15%

Inverted CsPbI2Br perovskite solar cells (PSCs) still suffer from substantially non-radiative recombination losses at the perovskite interface, which limits the future advancement of CsPbI2Br perovskite-based single- and multi-junction photovoltaic cells. Interfacial defect passivation of perovskite films is an effective approach for enhancing the performance of PSCs. In this study, we introduce thiophene halide salts with different side groups on the surface of CsPbI2Br films to passivate the inorganic perovskite film and investigate their passivation effects. Our studies show that the 2-thiophenemethylammonium iodide (TM) passivator with –CH2NH3I side group effectively mitigates the trap density of the perovskite film by forming coordination bonding with Pb2+ ions, thus significantly inhibiting the non-radiative recombination in the resulting PSC. In addition, after the TM treatment, the better energy-level alignment between the CsPbI2Br/[6,6]-Phenyl C61 butyric acid methyl ester (PCBM) interface is achieved, thus enhancing the charge extraction from perovskite to the charge transport layer. The resulting inverted CsPbI2Br device demonstrates a significantly enhanced champion efficiency of 15.07% with a Voc of 1.16 V, Jsc of 16.42 mA/cm2, and FF of 79.11%, compared to the 11.19% efficiency of the control device, and maintains >97% of the initial efficiency after being stored for over 1700 h in N2 atmosphere. This work confirms the importance of substituent groups on surface passivation molecules for effective passivation of defects and optimization of energy levels, particularly for Voc improvement.

Comparative performance analysis of poly (3-hexylthiophene-2, 5-dial) and [6,6]-phenyl-C61 butyric acid methyl ester-based organic solar cells in bulk-heterojunction and bilayer structure using SCAPS

This work is concerned with the design and photovoltaic performance study of organic semiconducting materials-based solar cells using a SCAPS simulator. Organic solar cells are one form that absorbs light and produces electricity. They exhibit high power conversion efficiency, low manufacturing costs, lightweight, and flexibility which makes them a promising technology for renewable energy. We developed and designed organic solar cell devices with the structure ITO/PEDOT: PSS/P3HT: PCBM/PFN-Br/Al for bulk-heterojunction structure and ITO/PEDOT: PSS/P3HT: PCBM/PFN-Br/Al for bilayer structure where PEDOT: PSS and PFN-Br were used as hole and electron transporting layers (HTL and ETL) respectively. The short circuit current density versus voltage (J-V) characteristics as well as photovoltaic parameters namely open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF), and power conversion efficiency (PCE) have been examined. In addition, the quantum efficiency (QE) of the two structures has been also studied. The effectiveness of the photovoltaic simulated systems has also been attempted to be enhanced by varying the absorber layer's thickness for both architectures. Later, this turned out that variations in the band gap of the absorber layer had an impact on the factors that determined how well solar cells performed. It has been found that the simulated bulk-heterojunction device exhibits 20.43% PCE whereas 3.52% PCE has been calculated from the simulated bilayer device.

Toward Low-Voltage and High-Sensitivity Direct X-ray Detectors Based on Thick Bulk Heterojunction Organic Device.

Organic semiconducting materials are promising for the fabrication of flexible ionizing radiation detectors for imaging because of their tissue equivalence, simple large-scale processing, and mass production. However, it is challenging to achieve high-sensitivity detection for organic direct detectors prepared by low-cost solution processing because of the compromise between thickness and carrier transport. In this study, high-performance organic direct X-ray detectors were fabricated by building a micrometer-thick bulk heterojunction (BHJ) using poly(3-hexylthiophene-2,5-diyl) (P3HT):(6,6)-phenyl c71 butyric acid methyl ester. A 5 μm BHJ film was fabricated by drop-casting and enhanced crystallization of P3HT using binary solvents and high-boiling-point additives to improve the charge carrier mobility. Furthermore, this organic direct X-ray detector has a sensitivity of >654.26 μC Gyair s-1 and a self-powered response. Because of the architecture of the thick active layer and the energy cascade in this diode detector, it has a very low dark current of 46.26 pA at -2 V. A fast and efficient approach was developed for fabricating thick, highly mobile organic BHJ films for high-performance direct X-ray detectors. It has great potential for application in a new generation of flexible and portable large-area flat-panel detectors.

Insulating 6,6-Phenyl-C61-butyric Acid Methyl Ester on Transition-Metal Dichalcogenides: Impact of the Hybrid Materials on the Optical and Electrical Properties.

In this study we develop a strategy to insulate 6,6 -Phenyl C61 butyric acid methyl ester (PCBM) on the basal plane of transition metal dichalcogenides (TMDs). Concretely single layers of MoS2, MoSe2, MoTe2, WS2, WSe2 and WTe2 and ultrathin MoO2 and WO2 were grown via chemical vapor deposition (CVD). Then, the thiol group of a PCBM modified with cysteine reacts with the chalcogen vacancies on the basal plane of TMDs, yielding PCBM-MoS2, PCBM-MoSe2, PCBM-WS2, PCBM-WSe2, PCBM-WTe2, PCBM-MoO2 and PCBM-WO2. Afterwards, all the hybrid materials were characterized using several techniques, including XPS, Raman spectroscopy, TEM, AFM, and cyclic voltammetry. Furthermore, PCBM causes a unique optical and electrical impact in every TMDs. For MoS2 devices, the conductivity and photoluminescence (PL) emission achieve a remarkable enhancement of 1700 % and 200 % in PCBM-MoS2 hybrids. Similarly, PCBM-MoTe2 hybrids exhibit a 2-fold enhancement in PL emission at 1.1 eV. On the other hand, PCBM-MoSe2, PCBM-WSe2 and PCBM-WS2 hybrids exhibited a new interlayer exciton at 1.29-1.44, 1.7 and 1.37-154 eV along with an enhancement of the photo-response by 2400, 3200 and 600 %, respectively. Additionally, PCBM-WTe2 and PCBM-WO2 showed a modest photo-response, in sharp contrast with pristine WTe2 or WO2 which archive pure metallic character.

Effect of Anode Interfacial Modification by Self-Assembled Monolayers on the Organic Solar Cell Performance.

A series of self-assembled monolayer (SAM)-based benzoic acid derivatives such as 4-[5'-phenyl-2,2'-bitien-5-yl] benzoic acid (ZE-Ph), 4-[5'-(4-fluorophenyl)-2,2'-bitien-5-yl]benzoic acid (ZE-1F), and 4-[5'-(3,5-difluorophenyl)-2,2'-bitien-5-yl]benzoic acid (ZE-2F) were synthesized to use an interlayer between an ITO electrode and a MoO3 thin film layer in an organic solar cell (OSC) having poly-3 hexylthiophene (P3HT): [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) blend. The work function and surface wetting properties of the ITO were tuned by SAM molecules. The power conversion efficiency of fabricated OSC devices was improved compared to that of the control device from 1.93 to 2.20% and 2.22% with ZE-Ph and ZE-1F-modified ITO electrodes, respectively. The short-circuit current density (Jsc) was increased from 6.16 to 7.10 mA/cm2 and 6.94 mA/cm2 with control, ZE-Ph, and ZE-1F-modified solar cells, respectively. The increase in short-circuit current density (Jsc) shows that the hole-transporting properties between ITO and MoO3 were improved by the use of ZE-Ph and ZE-1F compared with that of the ITO/MoO3 electrode configuration. The open-circuit voltage (Voc) of the SAM-modified ITO-based devices was also improved compared with the Voc of unmodified ITO-based devices. These results show that using a monolayer as an interlayer in OSCs is an important strategy to improve the performance of OSCs. All the device parameters were characterized by Kelvin probe force microscopy, cyclic voltammetry, contact angle, and I-V measurements.

Enhanced Efficiency and Stability of Inverted CsPbI2Br Perovskite Solar Cells via Fluorinated Organic Ammonium Salt Surface Passivation.

All-inorganic perovskite solar cells (PSCs) have recently received increasing attention due to their outstanding thermal stability. However, the performance of these devices, especially for the devices with a p-i-n structure, is still inferior to that of the typical organic-inorganic counterparts. In this study, we introduce phenylammonium iodides with different side groups on the surface of the CsPbI2Br perovskite film and investigate their passivation effects. Our studies indicate that the 4-trifluoromethyl phenylammonium iodide (CFPA) molecule with the -CF3 side group effectively decreases the trap density of the perovskite film by forming interactions with the undercoordinated Pb2+ ions and significantly inhibits the nonradiative recombination in the derived PSC, leading to an enhanced open-circuit voltage (Voc) from 0.96 to 1.10 V after passivation. Also, the CFPA post-treatment enables better energy-level alignment between the conduction band minimum of CsPbI2Br perovskite and [6,6]-phenyl C61 butyric acid methyl ester, thereby enhancing the charge extraction from the perovskite to the charge transport layer. These combined benefits result in a significant enhancement of the power conversion efficiency from 11.22 to 14.37% for inverted CsPbI2Br PSCs. The device without encapsulation exhibits a degradation of only ≈4% after 1992 h in a N2 glovebox.

Structure-Property Relationships for the Electronic Applications of Bis-Adduct Isomers of Phenyl-C61 Butyric Acid Methyl Ester.

Higher adducts of a fullerene, such as the bis-adduct of PCBM (bis-PCBM), can be used to achieve shallower molecular orbital energy levels than, for example, PCBM or C60. Substituting the bis-adduct for the parent fullerene is useful to increase the open-circuit voltage of organic solar cells or achieve better energy alignment as electron transport layers in, for example, perovskite solar cells. However, bis-PCBM is usually synthesized as a mixture of structural isomers, which can lead to both energetic and morphological disorder, negatively affecting device performance. Here, we present a comprehensive study on the molecular properties of 19 pure bis-isomers of PCBM using a variety of characterization methods, including ultraviolet photoelectron spectroscopy, thermal gravimetric analysis, differential scanning calorimetry, single crystal structure, and (time-dependent) density functional theory calculation. We find that the lowest unoccupied molecular orbital of such bis-isomers can be tuned to be up to 170 meV shallower than PCBM and up to 100 meV shallower than the mixture of unseparated isomers. The isolated bis-isomers also show an electron mobility in organic field-effect transistors of up to 4.5 × 10-2 cm2/(V s), which is an order of magnitude higher than that of the mixture of bis-isomers. These properties enable the fabrication of the highest performing bis-PCBM organic solar cell to date, with the best device showing a power conversion efficiency of 7.2%. Interestingly, we find that the crystallinity of bis-isomers correlates negatively with electron mobility and organic solar cell device performance, which we relate to their molecular symmetry, with a lower symmetry leading to more amorphous bis-isomers, less energetic disorder, and higher dimensional electron transport. This work demonstrates the potential of side chain engineering for optimizing the performance of fullerene-based organic electronic devices.

Equal proportion of donor/acceptor active layer for reduced dark current in visible organic photodiode

The present study investigates a visible organic photodiode with low dark current of 0.002 mA/cm2. The active layer is a bulk heterojunction (BHJ) binary blended film composed of Poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) as a donor material along with (6,6)-Phenyl C71 butyric acid methyl ester (PC71BM) as an acceptor material. The device was fabricated using a facile spin coating technique with the structure of ITO/PEDOT:PSS/PCDTBT:PC71BM/Al. The composition of PCDTBT and PC71BM has significantly improved the absorption of the UV–visible spectrum, especially between 300 and 650 nm. The optimized device of the blended film (1:1 blend ratio) showed a good photoresponsivity of 114 mA/W, with a fast response-recovery time of 733 ms and 597 ms, respectively. It is found that the specific detectivity obtained is 1.79×109 Jones and external quantum efficiency (EQE) is 29.13 %. The results manifested the optimized device can be employed in the fabrication of a cost-effective and highly sensitive visible organic photodiode.

Highly efficient lead-free ethyl ammonium substituted perovskite solar cell simulated using SCAPS 1D

This computational study investigated a lead (Pb)-free ethyl ammonium (EA) substituted ethylenediamine (EDA) based ((FA0.9EA0.1)0.98EDA0.01SnI3) perovskite solar cell (PSC) using the solar cell capacitance one-dimensional simulator (SCAPS 1D). The initial device schematic comprised ((FA0.9EA0.1)0.98EDA0.01SnI3) based perovskite as an absorber layer with copper (I) oxide (Cu2O) and [6,6] phenyl-C61 butyric acid methyl ester (PCBM) as hole and electron transport layers, where the device efficiency was 21.87%. The impacts of numerous electron transport layers (ETLs) and hole transport layers (HTLs) were also examined. The charge transport layers were optimized based on their energy levels and according to the relationship between the built-in potential (Vbi) and the open-circuit voltage (VOC). Numerical simulations showed that to circumvent the Vbi loss, the valence band (VB) maximum of HTL (EVB_HTL) should not be lower than the VB for perovskite (PVK) (EVB_PVK) for the appropriate selection of HTLs. Correspondingly, for the suitable selection of ETLs, the conduction band (CB) minimum of ETL (ECB_ETL) and the front contact should not be greater than the CB minimum for PVK (ECB_PVK). Therefore, the optimized ETLs and HTLs were obtained as zinc oxysulfide and copper (II) phthalocyanine, respectively, where the device's efficiency increased up to 22.36%. The effect of the thickness of the EDA-based PSCs was also examined and the optimized thickness was obtained as 1.1 μm, where the device's efficiency increased to 24.42%. This improvement in the performance of the device indicates that EA substituted EDA-based ((FA0.9EA0.1)0.98EDA0.01SnI3) PSC is a promising alternative for use in Pb-free PSCs.

The novel n-channel liquid crystal organic field effect transistor (LC-n-OFET): A promising technology for low-power electronics

In this study, a novel n-channel liquid crystal organic field effect transistor (LC-n-OFET) was fabricated using a mixture of E7 nematic liquid crystal (NLC) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in an OFET cell. The LC-n-OFET performance was investigated regarding dielectric properties, UV illumination sensitivity, and channel length dependence. Output and transfer current-voltage (I–V) characteristics were measured to evaluate the electrical properties in dark and under UV illumination for varying channel lengths. Additionally, the dielectric characteristics of the LC-n-OFET were determined along with the capacitance-frequency response (Ci-f), threshold voltage (VTh), field-effect mobility (μFET), and on/off current ratio (Ion/off) as a function of UV illumination intensity and channel length changes. Electrical measurements showed the Ion/off current ratio is inversely proportional to channel length but directly proportional to UV intensity. Meanwhile, the threshold voltage (VTh) and mobility (μFET) increased with longer channel length and higher light intensity. Overall, the novel LC-n-OFET exhibited promising performance with low VTh, high μFET, and large Ion/off.

Scalable Solution-Processed Hybrid Electron Transport Layers for Efficient All-Perovskite Tandem Solar Modules.

All-perovskite tandem solar cells offer the potential to surpass the Shockley-Queisser (SQ) limit efficiency of single-junction solar cells while maintaining the advantages of low-cost and high-productivity solution processing. However, scalable solution processing of electron transport layer (ETL) in p-i-n structured perovskite solar subcells remains challenging due to the rough perovskite film surface and energy level mismatch between ETL and perovskites. Here, scalable solution processing of hybrid fullerenes (HF) with blade-coating on both wide-bandgap (≈1.80 eV) and narrow-bandgap (≈1.25 eV) perovskite films in all-perovskite tandem solar modules is developed. The HF, comprising a mixture of fullerene (C60 ), phenyl C61 butyric acid methyl ester, and indene-C60 bisadduct, exhibits improved conductivity, superior energy level alignment with both wide- and narrow-bandgap perovskites, and reduced interfacial nonradiative recombination when compared to the conventional thermal-evaporated C60 . With scalable solution-processed HF as the ETLs, the all-perovskite tandem solar modules achieve a champion power conversion efficiency of 23.3% (aperture area = 20.25 cm2 ). This study paves the way to all-solution processing of low-cost and high-efficiency all-perovskite tandem solar modules in the future.