Hole Mobility Research Articles

Parametric optimization for the performance analysis of novel hybrid organo-perovskite solar cell via SCAPS-1D simulation

The perovskite and organic solar cells are becoming the most cognizant of the photovoltaic communities. The Spiro-OMeTAD organic hole transport layer (HTL) shows a significant impact on the CH3NH3SnI3 perovskite solar cell (PSC) with TiO2 as the electron transport layer (ETL). So, we optimized the physical and electrical parameters of the organic HTL. Electrical optimization shows that the power conversion efficiency (PCE) of the cell can reach up to 18.10% for the electron affinity of the organic HTL material of about 2.5eV. Further, the interpretation of the practical scale of series and shunt resistance reveals the maximum PCE of the cell as 13.30% at 0.5Ωcm2 and 1×106Ωcm2 respectively. Also, the performance of the cell is analyzed for the hole mobility of the organic HTL material, which revealed the best PCE of the cell to 13.31%. Moreover, the physical parameters are also optimized for the cell performance with illumination intensities which pointed out that the performance of the novel organic HTL perovskite solar cell is optimum for illumination intensity around 0.5Sun (500Wm-2). Finally, the overall light harnessing efficiency or PCE of the proposed solar cell is declared to be 13.30%, and the other performance parameters as open circuit voltage (Voc), short circuit current (Jsc), and fill factor (FF) are 0.764V, 25.86mAcm−2 and 67.29%, respectively.

Correlating Chemical Structure and Charge Carrier Dynamics in Phenanthrocarbazole‐Based Hole Transporting Materials for Efficient Perovskite Solar Cells

ABSTRACTPolymeric hole transport materials (HTMs) have emerged because of their potential to produce dopant‐free, efficient, and stable perovskite solar cells (PSCs). Therefore, we engineered 10 novel donor materials (SMH1–SMH10) containing phenanthrocarbazole‐based polymeric structures for organic and PSCs. These molecules underwent bridging‐core modifications using different spacers, such as furan (N1), pyrrole (N2), benzene (N3), pyrazine (N4), dioxane (N5), isoxazole (N6), isoindole (N7), indolizine (N8), double bond (N9), and pyrimidine (N10), in comparison to reference molecule R. The study examined the structure–property relationship and the impact of these modifications on the optical, photovoltaic, photophysical, and optoelectronic characteristics of the newly designed SMH1–SMH10 series. Density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) calculations were conducted to analyze frontier molecular orbitals, density of states, reorganization energies, open‐circuit voltage, transition density matrix, and charge transfer processes. Results show that the newly designed molecules (SMH1–SMH10) exhibited superior optoelectronics characteristics compared to the R molecule. Among these, SMH4 is the most promising candidate, with a small band gap (2.79 eV), low electron and hole mobility (λe 0.0028 eV, λh 0.0020 eV), lower binding energy (Eb 0.58 eV), high λmax values (656.42 nm in gas, 573.34 nm in chlorobenzene), and a high Voc of 1.30 V. Therefore, this study demonstrated that bridging‐core modifications offer a simple and effective strategy for designing desirable characteristics molecules for photovoltaic applications.

Spatial Control of Nickel Vacancies in Colloidal NiMgO Nanocrystals for Efficient and Stable All‐inorganic Quantum Dot Light‐Emitting Diodes

AbstractColloidal quantum dot (QD)–based light‐emitting diodes (QD‐LEDs) have reached the pinnacle of quantum efficiency and are now being actively developed for next‐generation displays and brighter light sources. Previous research has suggested utilizing inorganic hole‐transport layers (HTLs) to explore brighter and more stable QD‐LEDs. However, the performance metrics of such QD‐LEDs with inorganic HTLs generally lag behind those of organic‐inorganic hybrid QD‐LEDs employing organic HTLs. In this study, colloidal NiMgO nanocrystals (NCs) with spatially controlled Mg are introduced as HTLs for realizing efficient and stable all‐inorganic QD‐LEDs. During the co‐condensation of Ni and Mg precursors to produce valence band‐lowered NiMgO NCs, incorporating ≈2% Mg into the NiO lattice creates additional Ni vacancies (VNi) within and on the NCs, influencing the hole concentration and mobility of the NiMgO NC films. Passivating the VNi exposed on the surface with magnesium hydroxide allows for tuning the electrical properties of the NiMgO NCs relative to those of an electron transport layer, allowing for a balanced charge supply and suppressed negative charging of the QDs. Optimized all‐inorganic QD‐LEDs employing NiMgO NCs achieved a peak external quantum efficiency of 16.4%, peak luminance of 269 455 cd m⁻2, and a half‐life of 462 690 h at 100 nit.

The importance of enhancing D-Dand A-Astacking simultaneously for the balance of hole and electron mobility of small molecule single-component organic solar cells.

Single-component organic solar cells (SCOSCs) have attracted extensive attention due to their simplified device manufacturing and excellent stability. However, the relationship between morphology and charge carrier mobility in the active layers of SCOSCs is not well understood. In this work, we present a comprehensive investigation on this issue by studying four dyads (fullerenes as acceptor units) used as materials of active layers in small-molecule single-component organic solar cells (SM-SCOSCs), in which dyad 4 created the record of power conversion efficiency (PCE) of SM-SCOSC until now. Utilizing a multiscale theoretical approach, the results identify that the acceptor-acceptor stacking is dominant in amorphous films, significantly improving electron mobility and lowering hole mobility. We also find the importance of achieving a balance between electron and hole mobility to further improve PCE of SM-SCOSC because dyad 4 exhibits a more balanced electron/hole mobility than the other three molecules. These findings indicate the importance of tuning and enhancing donor-donor and acceptor-acceptor stacking simultaneously, offering insights for the design and optimization of future SM-SCOSC.

Deep blue high-efficiency solution-processed triplet-triplet annihilation organic light-emitting diodes using bis(8-carbazol-N-yl)fluorene- and benzonitrile-modified anthracene/chrysene fluorescent emitters

Triplet-triplet annihilation (TTA) emitters can effectively utilize non-radiative triplet excitons through the interaction of low triplet energy excitons to produce high energy singlet excitons, but they are mostly restricted by their multilayered device structure fabricated using layer-by-layer thermal vacuum evaporation. It is a great challenge to develop, for the first time, efficient solution-processed non-doped TTA organic light-emitting diodes (OLEDs). In this study, two solution-processable blue emissive TTA molecules (FAnCN and FCsCN) bearing (anthracen-9-yl)benzonitrile (AnCN) and (chrysen-6-yl)benzonitrile (CsCN) as TTA emissive cores modified with 9,9′-bis(8-(carbazole-N-yl)octyl)fluorene (F) are designed and synthesized, respectively. The experimental and theoretical studies reveal that both molecules exhibit deep blue emissions, amorphous morphology with good thermal stability, high-quality solution-cast thin films, decent hole mobility, high-lying HOMO levels (∼-5.45 eV), and suitable lowest singlet (S1)/triplet (T1) excited states (2T1 > S1) for TTA process. FAnCN and FCsCN are successfully employed as solution-processed non-doped emissive layers (EML) in simple structured TTA OLEDs. These devices show intense blue emissions, low turn-on voltages (∼3.6 V), excellent electroluminescent (EL) performances (EQEmax = 5.47–6.84 % and LEmax = 5.66–5.83 cd/A), and TTA characteristics. Especially, FCsCN-based TTA OLED emits deep blue EL emission peaked at 435 nm with a high EQEmax of 6.84 %. This work not only presents a new strategic design for the preparation of solution-processable TTA emitter, but also further ratifies that the TTA mechanism can also be applicable in solution-processed OLEDs.

Tailoring Diversified Peripheral Anchor Groups in Spirofluorene‐Dithiolane‐Based Hole Transporting Materials for Efficient Organic and Perovskite Solar Cells from First‐Principle

AbstractThis quantum mechanical approach recommends push–pull molecular engineering to fabricate hole‐transporting materials (HTMs) for photovoltaic cells. It integrates acceptor moieties via thiophene to fluorene core, resulting in five novel HTMs (SFD‐1 to SFD‐5). The results exhibit that derivative HTMs show excellent coherence in excitation, dispersion, and transportation of charge carriers, ensuring robust hole mobility. The anchor moieties functionalized HTMs unveil excellent band alignment with perovskite with fitting HOMO energy levels (−4.93–−5.35 eV), less optical absorption in visible portion ( < 520). This acceptor integration has improved the hole mobility in derivatives, accredited to the smaller hole reorganization energy (0.14–0.68 eV), and greater hole transfer integral (0.22–0.33 eV). The transition density matrix analysis exhibited robust electronic coupling, subtler charge carrier overlapping and greater charge transfer length (7.48–13.73 Å). This resulted in an excellent upsurge in intrinsic charge transference (70.75–92.70%) and smaller exciton binding energy, leading to easier exciton dissociation, and fewer recombination fatalities. However, an adequate variation in dipole moment (4.04 D to 16.34 D) and Gibbs solvation‐free energy (−18.06 to −21.89 kcal mol−1) ensures facile film formation and processability. In conclusion, this approach recommends these flourene‐based HTMs are highly desireable for forthcoming solar cell technology.

Spin-Coated and Vacuum-Processed Hole-Extracting Self-Assembled Multilayers with H-Aggregation for High-Performance Inverted Perovskite Solar Cells.

We report a highly crystalline self-assembled multilayer (SAMUL) that is fundamentally different from the conventional monolayer or disordered bilayer used for hole-extraction in inverted perovskite solar cells (PSCs). The SAMUL can be easily formed on ITO substrate to establish better surface coverage to enhance the performance and stability of PSCs. A detailed structure-property-performance relationship of molecules used for SAMUL is established through a systematic study of their crystallinity, molecular packing, and hole-transporting properties. These SAMULs are rationally optimized by varying their molecular structures and deposition methods through thermal evaporation or spin-coating for fabricating PSCs. The CbzNaphPPA-based SAMUL was chosen for fabricating inverted PSCs due to it exhibiting the highest crystallinity and hole mobility which is derived from the ordered H-aggregation. This resulted in a remarkably high fill factor of 86.45 %, which enables a very impressive power conversion efficiency (PCE) of 26.07 % to be achieved along with excellent device stability (94 % of its initial PCE retained after continuous operation for 1200 h under 1-sun irradiation at maximum power point at 65 °C). Additionally, a record-high PCE of 23.50 % could be achieved by adopting a thermally evaporated SAMUL. This greatly simplifies and broadens the scope for SAM to be used for large-area devices on diverse substrates.

Spin‐Coated and Vacuum‐Processed Hole‐Extracting Self‐Assembled Multilayers with H‐Aggregation for High‐Performance Inverted Perovskite Solar Cells

AbstractWe report a highly crystalline self‐assembled multilayer (SAMUL) that is fundamentally different from the conventional monolayer or disordered bilayer used for hole‐extraction in inverted perovskite solar cells (PSCs). The SAMUL can be easily formed on ITO substrate to establish better surface coverage to enhance the performance and stability of PSCs. A detailed structure‐property‐performance relationship of molecules used for SAMUL is established through a systematic study of their crystallinity, molecular packing, and hole‐transporting properties. These SAMULs are rationally optimized by varying their molecular structures and deposition methods through thermal evaporation or spin‐coating for fabricating PSCs. The CbzNaphPPA‐based SAMUL was chosen for fabricating inverted PSCs due to it exhibiting the highest crystallinity and hole mobility which is derived from the ordered H‐aggregation. This resulted in a remarkably high fill factor of 86.45 %, which enables a very impressive power conversion efficiency (PCE) of 26.07 % to be achieved along with excellent device stability (94 % of its initial PCE retained after continuous operation for 1200 h under 1‐sun irradiation at maximum power point at 65 °C). Additionally, a record‐high PCE of 23.50 % could be achieved by adopting a thermally evaporated SAMUL. This greatly simplifies and broadens the scope for SAM to be used for large‐area devices on diverse substrates.

Novel Self-Assembling Supramolecular Phenanthro[9,10-a]phenazine Discotic Liquid Crystals: Synthesis, Characterization and Charge Transport Studies.

The incorporation of heteroatoms in the chemical structure of organic molecules has been identified as analogous to the doping process adopted in silicon semiconductors to influence the nature of charge carriers. This strategy has been an eye-opener for material chemists in synthesizing new materials for optoelectronic applications. Phenanthro[9,10-a]phenazine-based mesogens have been synthesized via a cyclo-condensation pathway involving triphenylene-based diketone and o-phenyl diamines. The incorporation of phenazine moiety as discussed in this paper, alters the symmetric nature of the triphenylene. The phenanthro[9,10-a]phenazine-based mesogens exhibit hole mobility in the order of 10-4 cm2/Vs as measured by the space-charge limited current (SCLC) technique. The current density in the SCLC device increases with increasing temperature which indicates that the charge transport is associated with the thermally activated hopping process. This report attempts to elucidate the self-organization of asymmetric phenanthro[9,10-a] phenazine in the supramolecular liquid crystalline state and their potential for the fabrication of high-temperature optoelectronic devices. However, the low charge carrier mobility can be one of the challenges for device performance.

Transparent p-type copper iodide for next-generation electronics: fundamental physics and recent research trends

Development of transparent and flexible p -type semiconductors has been a significant challenge for scientific curiosity and industrial interest. Unlike n -type metal oxide semiconductors, such as zinc oxide (ZnO), In2O3, and SnO2, transparent p -type oxide semiconductors have suffered from low optical transparency and poor electrical performance. To overcome the intrinsic limitation of p -type oxide semiconductors, copper iodide (CuI) is gaining attention as a multifunctional p -type semiconductor with excellent optical transparency, decent mechanical flexibility, high hole mobility, high electrical conductivity, and even promising thermoelectric performance. Here, we present the recent progress of CuI-based transparent p -type electronics from materials to applications. In this review, we summarize the physical and chemical properties of CuI by reviewing computational studies, focusing on the band structure, intrinsic defects, and promising dopants. Additionally, various applications of CuI, including its use as active layers, hole transport layers (HTLs), transparent electrodes, and energy harvesters, are examined, highlighting important studies and their findings. Strategies to enhance device performance, such as controlling carrier concentrations and refining fabrication methods, are discussed, offering insights for developing next-generation electronic devices. Finally, we discuss current challenges and perspective opportunities of CuI-based transparent p -type electronics.

Au-induced crystallization of amorphous Ge thin films: An indication of the existence of a recrystallization process during growth at deep subeutectic temperature

The influence of Au catalyst microstructure on the crystallization behavior of Ge thin films obtained by Au-induced crystallization method is studied. By improving the Au catalyst crystallinity by pre-annealing, the hole mobility of Ge thin film crystallized at 200°C is improved to nearly 150 cm2/Vs thanks to the increase in Ge grain size, which is fairly high for a Ge film as thin as 10 nm. It is found that the increase in Ge grain size originates from the recrystallization process at deep subeutectic temperature. This is attributed to the existence of a metastable AuGe alloy phase surrounding crystalline Ge, which is kinetically stabilized by a continuous flow of Ge atoms through the alloy phase and realizes a solution-like growth. The process using a kinetically stabilized metastable phase will open up the possibility to realize a novel cost-effective and low-temperature process to fabricate high-performance semiconductor devices on plastic substrates.

In-plane anisotropic dispersion property and second-harmonic generation of violet phosphorus with two-dimensional nano-interlocking structure

The unique one-dimensional chain structure of violet phosphorus provides an ideal platform for the study of second-order nonlinear optical properties. This also offers more possibilities for the further development of novel two-dimensional layered nanomaterials in the frequency domain. The research suggest that the highest occupied molecular orbital of monolayer phosphorene is characterized by a small effective mass and high hole mobility, while the lowest unoccupied molecular orbital exhibits opposite properties. This may be attributed to increased lattice scattering or electron-electron interactions in the conduction band. Monolayer violet phosphorus exhibits strong absorption capabilities in the near-ultraviolet light range, which can be utilized in UV spectroscopy technology for detecting harmful substances in water and air. Besides, its second harmonic generation response is also very strong within the visible light spectrum, and this response significantly varies with changes in angle. This provides theoretical guidance for optimizing the different stacking directions and heterojunction structures of violet phosphorus, more importantly, the sensitivity and directional selectivity of sensors can be improved. The work not only deepens the understanding of the electro-optical performance of violet phosphorus materials but also lays a theoretical foundation and guidance for the design and application of devices based on violet phosphorus.

Theoretical prediction of holes and electrons mobility in coronene and perchlorocoronene crystals: Application of the Marcus–Jortner–Levich Theory

The study focused on theoretically predicting charge carrier mobilities in coronene and perchlorocoronene crystals using the Marcus–Levich–Jortner approach. By analyzing charge transfer integrals and considering hopping pathways, significant anisotropy in charge transfer was observed. Density functional theory (DFT) calculations at the B3LYP-D3/6-311++G(d,p) and ωB97X-D/6-311++G(d,p) levels were employed to assess the impact of normal modes on reorganization energies and charge transfer rates. Results indicated that perchlorination reduced mobility for both holes and electrons. Notably, maximum mobilities were observed at the melting points: 0.0120 cm2 V−1 s−1 for electrons and 0.0798 cm2 V−1 s−1 for holes in coronene at 455 K, and 0.0032 cm2 V−1 s−1 for electrons and 0.0426 cm2 V−1 s−1 for holes in perchlorocoronene at 560 K. This suggests that both crystals exhibit favorable charge transport characteristics near their respective melting points.

Machine Learning-Inspired Molecular Design, Divergent Syntheses, and X-Ray Analyses of Dithienobenzothiazole-Based Semiconductors Controlled by S⋅⋅⋅N and S⋅⋅⋅S Interactions.

Inspired by the previous machine-learning study that the number of hydrogen-bonding acceptor (NHBA) is important index for the hole mobility of organic semiconductors, seven dithienobenzothiazole (DBT) derivatives 1 a-g (NHBA=5) were designed and synthesized by one-step functionalization from a common precursor. X-ray single-crystal structural analyses confirmed that the molecular arrangements of 1b (the diethyl and ethylthienyl derivative) and 1c (the di(n-propyl) and n-propylthienyl derivative) in the crystal are classified into brickwork structures with multidirectional intermolecular charge-transfer integrals, as a result of incorporation of multiple hydrogen-bond acceptors. The solution-processed top-gate bottom-contact devices of 1b and 1c had hole mobilities of 0.16 and 0.029 cm2 V-1s-1, respectively.

A Self‐Assembling Molecule for Improving the Mobility in PEDOT:PSS Hole Transport Layer for Efficient Perovskite Light‐Emitting Diodes

AbstractPoly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), the most widely used hole injection layer (HIL) for perovskite light‐emitting diodes (PeLEDs), has a large hole injection energy barrier and easy charge separation at PEDOT:PSS/perovskite layer. Here, a self‐assembling molecule (SAM) called (2‐(3,6‐dimethoxy‐9H‐carbazol‐9‐yl)ethyl) phosphonic acid (MeO‐2PACz) is introduced as an interlayer between PEDOT:PSS and perovskite to overcome the limitations of PEDOT:PSS HIL. The MeO‐2PACz interlayer facilitated hole injection due to the reduced hole injection energy barrier and the improved hole mobility, enhanced photoluminescence (PL) due to the prevented charge transfer from perovskite into PEDOT:PSS, and reduced interface trap density due to the passivation of methoxy and carbazole group toward perovskite. As a result, PeLEDs with MeO‐2PACz interlayer has greatly enhanced maximum luminance (Lmax = 17,310 cd m−2) and reduced leakage current, resulting in higher maximum external quantum efficiency (EQEmax = 21.50%) compared to pristine Control device (EQEmax of 4.82%).

Heterojunction photoelectric device with fast response speed and low power consumption composed of WSSe and AlN

Through the accurate calculation of density functional theory, reveal the excellent photoelectric properties of the AlN/WSSe and WSSe/AlN heterojunction. Especially, the hole mobility of the AlN/WSSe heterojunction is as high as 3919 cm2Vs-1in armchair direction, and the hole mobility of the WSSe/AlN heterojunction is as high as 4422 cm2Vs-1in the zigzag direction. Interestingly, when two H atoms are adsorbed in the WSSe surface, the Gibbs free energy change are -0.093 eV and -0.984 eV, which tends to zero, which can promote the spontaneous reaction of electrocatalytic water decomposition to produce H2. In addition, the AlN/WSSe heterojunction exhibits significant photoelectric effect photocurrent (1.15 a02/photon) in the armchair direction and the heterojunctions have lower threshold voltage (1.5 V), that indicate the AlN/WSSe and WSSe/AlN heterojunction have great application prospect in manufacturing high-performance optoelectronic devices with fast response and low power consumption.

Solution-processed NO2 gas sensor based on poly(3-hexylthiophene)-doped PbS quantum dots operable at room temperature

The global industrial development and increase in the number of transportation vehicles, such as automobiles and ships, have led to a steady increase in the issues related to greenhouse gas emissions. NO2 is a greenhouse gas emitted in large quantities from automobiles and factories, and its emission is unavoidable in the modern world. Therefore, a sensor capable of precise detection of NO2 is required. The most commonly reported types of NO2 sensors are those based on metal oxides. However, their operation at room temperature is impossible owing to their high-temperature operating characteristics, and therefore, a heater must be designed inside or installed outside the sensor for heating. Meanwhile, NO2 sensors based on PbS quantum dots (QDs) are advantageous as they can operate at room temperature and can be easily manufactured through a solution process rather than a complicated semiconductor process. Herein, a NO2 sensor was fabricated by doping PbS QDs with poly(3-hexylthiophene) (P3HT). The as-developed sensor exhibited high responsivity to 100–0.4-ppm NO2 gas with a resolution of 200 ppb owing to the stability of the thin film and high hole mobility of P3HT.

Advancements in optical and optoelectronic characteristics of benzotriazole-based asymmetric non-fullerene acceptors for organic photovoltaics

The development of energy-efficient non-fullerene acceptors (NFAs) has attracted much attention in producing efficient organic solar cells (OSCs). These innovative materials are considered a promising alternative to traditional fullerene acceptors because they absorb a broader light range and potentially enhance the OSC performance. Herein, we engineered eleven new asymmetric caterpillar-shaped materials with an A1-D-A2-A1 core as NFAs for OSCs. These efficient materials offer a high absorption efficiency, wide energy level range, and efficient charge transport capabilities. To engineer these caterpillar-shaped NFAs (FT1-FT11), we performed various synergistic modulations of end-capped electron-withdrawing moieties and side-chain engineering on the synthetic reference molecule (FT). The electron and hole reorganization energies, binding energy, transition energy, transition density analysis, electrostatic potential, and photovoltaic characterizations have been performed for these designed caterpillar-shaped (FT1–FT11) series. The designed materials (FT1–FT11) showed a lower binding energy of 0.45 eV, a narrower bandgap (2.11 eV), higher absorption (ranges from 700.44 nm to 781.05), and low electron and hole mobilities (0.0029 and 0.0031) compared to reference molecule FT. To investigate the charge transport process, we employed polymer donor PTB7-Th and efficient NFA acceptor FT11 to establish a donor:acceptor complex (FT11:PTB7-Th). The complex study demonstrates a significant charge transformation at the donor-acceptor interface. As a result, the developed compounds (FT1–FT11), with their superior optoelectronic capabilities, could be viewed as a viable and sustainable choice to fabricate next-generation efficient OSCs.

New Bipolar Host Materials Based on Indolocarbazole for Red Phosphorescent OLEDs.

We designed and synthesized new indolocarbazole-triazine derivatives, 9-di-tert-butyl-5,7-bis(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-5,7-dihydroindolo[2,3-b]carbazole (2TRZ-P-ICz) and 3,9-di-tert-butyl-5,7-bis(5'-(4,6-diphenyl-1,3,5-triazin-2-yl)-[1,1':3',1″-terphenyl]-2'-yl)-5,7-dihydroindolo[2,3-b]carbazole (2TRZ-TP-ICz), as new bipolar host materials for red phosphorescent OLEDs. In the film state, 2TRZ-P-ICz and 2TRZ-TP-ICz exhibited photoluminescence maxima at 480 nm and 488 nm, respectively. The dipole moment characteristics of the new compounds under various solvent conditions were investigated using the Lippert-Mataga equation. The results showed that the dipole moment of 2TRZ-P-ICz is 26.9D, while that of 2TRZ-TP-ICz is 21.3D. The delayed fluorescence lifetimes were 0.188 μs for 2TRZ-P-ICz and 2.080 μs for 2TRZ-TP-ICz, with 2TRZ-TP-ICz showing TADF characteristics. Additionally, 2TRZ-TP-ICz was found to have a ΔEST of less than 0.2 eV. The triplet energy levels of the newly synthesized bipolar host materials were found to be 2.72 and 2.75 eV, confirming their suitability for use in red phosphorescent OLEDs. To investigate the carrier mobility of the synthesized materials, hole-only devices and electron-only devices were fabricated and tested. The hole mobility value at 1V was found to be 3.43 × 10-3 cm2/Vs for 2TRZ-P-ICz and 2.16 × 10-3 cm2/Vs for 2TRZ-TP-ICz. For electron mobility at 1V, 2TRZ-P-ICz showed a value of 4.41 × 10-9 cm2/Vs, while 2TRZ-TP-ICz exhibited a value of 9.13 × 10-9 cm2/Vs. As a result, when the new material was used as a host in red phosphorescent OLEDs, 2TRZ-TP-ICz achieved a current efficiency of 9.92 cd/A, an external quantum efficiency of 13.7%, CIE coordinates of (0.679, 0.319), and an electroluminescence maximum wavelength of 626 nm.

Improvement of Perovskite Solar Cells Efficiency by Management of the Electron Withdrawing Groups in Hole Transport Materials: Theoretical Calculation and Experimental Verification.

Management of functional groups in hole transporting materials (HTMs) is a feasible strategy to improve perovskite solar cells (PSCs) efficiency. Therefore, starting from the carbazole-diphenylamine-based JY7 molecule, JY8 and JY9 molecules are incorporated into the different electron-withdrawing groups of fluorine and cyano groups on the side chains. The theoretical results reveal that the introduction of electron-withdrawing groups of JY8 and JY9 can improve these highest occupied molecular orbital(HOMO)energy levels, intermolecular stacking arrangements, and stronger interface adsorption on the perovskite. Especially, the results of molecular dynamics (MD) indicate that the fluorinated JY8 molecule can yield a preferred surface orientation, which exhibits stronger interface adsorption on the perovskite. To validate the computational model, the JY7-JY9 are synthesized and assembled into PSC devices. Experimental results confirm that the HTMs of JY8 exhibit outstanding performance, such as high hole mobility, low defect density, and efficient hole extraction. Consequently, the PSC devices based on JY8 achieve a higher PCE than those of JY7 and JY9. This work highlights the management of the electron-withdrawing groups in HTMs to realize the goal of designing HTMs for the improvement of PSC efficiency.