Hole Mobility Research Articles

Temperature and refractive index sensor based on perfect absorber in InSb double rectangular ring resonator metamaterials

InSb is an important semiconductor material in the field of optoelectronic devices due to its high electron and hole mobility, low effective mass, and low energy gap at room temperature. In this paper, a thermally controlled dual-band terahertz metamaterial absorber with a patterned InSb film is designed and studied. The unit cell of the proposed metamaterial is composed of combined InSb double rectangular ring resonators (DRRR) adhered on a continuous gold layer and substrate. Finite-difference-time-domain (FDTD) simulation results demonstrate that the absorption peak can reach 98.95 %, and 99.45 % at 1.499 THz and 1.592 THz when the external environment temperature is 283 K. Electric field distribution and parameter sweep indicate the two absorption peaks result from the near-field coupled linear superposition between the big square and small square resonators. The proposed absorber not only has the features of wide incident-angle stability, but also polarization insensitivity. Besides, the proposed absorber shows temperature-tunable features due to the temperature-dependent variation of the permittivity of InSb material. The InSb pattern proposed in this paper provides an alternative method for designing of dual parameters sensor in the terahertz band, the proposed dual-band absorber can function as a temperature sensor with sensitivities of about 8.6 GHz/K and 12.8 GHz/K, respectively. The proposed dual-band absorber can also be used as a refractive index sensor with sensitivities of about 1.065 THz /RIU, and 0.499 THz /RIU, respectively. Therefore, the present work provides an effective method for implementing thermally and refractive index sensors in the terahertz range.

Elucidating the Role of InGaAs and InAlAs Buffers on Carrier Dynamics of Tensile-Strained Ge Double Heterostructures.

Extensive research efforts of strained germanium (Ge) are currently underway due to its unique properties, namely, (i) possibility of band gap and strain engineering to achieve a direct band gap, thus exhibiting superior radiative properties, and (ii) higher electron and hole mobilities than Si for upcoming technology nodes. Realizing lasing structures is vital to leveraging the benefits of tensile-strained Ge (ε-Ge). Here, we use a combination of different analytical tools to elucidate the effect of the underlying InGaAs/InAlAs and InGaAs overlaying heterostructures on the material quality and strain state of ε-Ge grown by molecular beam epitaxy. Using X-ray analysis, we show the constancy of tensile strain in sub-50 nm ε-Ge in a quantum-well (QW) heterostructure. Further, effective carrier lifetime using photoconductive decay as a function of buffer type exhibited a high (low) defect-limited carrier lifetime of ∼68 ns (∼13 ns) in 0.61% (0.66%) ε-Ge grown on an InGaAs (InAlAs) buffer. These results correspond well with the measured surface roughness of 1.289 nm (6.303 nm), consistent with the surface effect of the ε-Ge/III-V heterointerface. Furthermore, a reasonably high effective lifetime of ∼78 ns is demonstrated in a QW of ∼30 nm 1.6% ε-Ge, a moderate reduction from ∼99 ns in uncapped ε-Ge, alluding to the surface effect of the overlying heterointerface. Thus, the above results highlight the prime quality of ε-Ge that can be achieved via III-V heteroepitaxy and paves a path for integrated Ge photonics.

Structure-optoelectronic properties correlation of fluorene-based blue fluorescence emitters with different pendant moieties

Fluorene is a blue luminous moiety attracting wide attention due to its all kinds of high technology applications, and the rigid biphenyl planar structure of fluorene makes it prone to crystalize and form intermolecular aggregation, which means that emitting colors and carrier mobilities of fluorene-based fluorescence emitters are highly adjustable by the modification of 9,9-position of fluorene with different pendant moieties. In this regard, fluorene (F) is used as a model blue emitter, and different pendant groups of n-butyl, p-hexyloxy phenyl and 2,4,6-triphenyl-1,3,5-triazine are introduced into the 9-position of fluorene to produce four topology-varied organic light-emitting emitters, namely 9,9-dibutyl-fluorene (DBF), 9,9-bis-(4-butoxy-phenyl)-fluorene (BOPF), 2-{4-[9-(4-hexyloxy-phenyl)-fluoren-9-yl]-phenyl}-4,6-diphenyl- (Chan et al., 2017; Wex and Kaafarani, 2017; Liang et al., 2019) [1,3,5]triazine (FTRZ) and 2,4,6-tris-{4-[9-(4-hexyloxy-phenyl) -fluoren-9-yl]-phenyl}- (Chan et al., 2017; Wex and Kaafarani, 2017; Liang et al., 2019) [1,3,5]triazine (pTFTRZ). The general differences in thermal stability, photoluminescence quantum efficiency, emission wavelength, electrochemical energy levels, crystal structure, carrier mobility and film morphology of the emitters are experimentally and theoretically studied to correlate their structures with optoelectronic properties. FTRZ and pTFTRZ solid powder show higher melting points of 186 °C and 122 °C. The highest occupied molecular orbit energy levels are −5.95 eV for F, −6.02 eV for DBF, −6.11 eV for BOPF and −6.23 eV for FTRZ, and the corresponding lowest unoccupied molecular orbits energy levels are −2.03 eV for F, −2.19 eV for DBF, −2.25 eV for BOPF and −2.55 eV for FTRZ. When compared with the other three emitters, due to the enhanced intramolecular charge transfer caused by the electron-deficient 2,4,6-triphenyl-1,3,5-triazine group, FTRZ showed significant redshifts of 75 nm in their emission spectrum of solution, and the photoluminescence quantum efficiencies of FTRZ and pTFTRZ solid powder were also decreased to less than 1%. The single crystal of F is an orthorhombic system while those of DBF, BOPF and FTRZ are all monoclinic system. The electron and hole mobilities of the thin solid films were decreased in the order of FTRZ, BOPF and pTFTRZ, and thin solid film of FTRZ showed the highest electron mobility of 10−4cm2/V • s at an electric field of 4 × 104 V/cm. The RMS values corresponding to root-mean-square averages of the height deviations of film measured by atomic force microscopy are 4.32 nm for BOPF, 1.11 nm for FTRZ, 11.8 nm for pTFTRZ. The FTRZ films exhibited smaller RMS and smooth surface morphology beneficial for the carrier mobility relative to those of BOPF and pTFTRZ. The pendant groups of n-butyl, p-hexyloxy phenyl and 2,4,6-triphenyl-1,3,5-triazine in the 9-position of fluorene adjust the general optoelectronic properties of the obtained emitters in a wide range.

High‐Performance Tin‐Halide Perovskite Transistors Enabled by Multiple A‐Cation Engineering

AbstractMetal‐halide perovskite semiconductors have garnered great attention in optoelectronic devices due to their remarkable properties and processing capabilities. Among them, tin (Sn2+) perovskites stand out as promising candidates for use as channel layers in high‐performance p‐channel thin‐film transistors (TFTs) owing to their excellent hole transport property. In this study, a multi A‐cation approach is applied to pure Sn2+ perovskite, incorporating a small amount (7 mol%) of bulky PEA+ cation. This addition greatly improved the crystallinity and orientation of 3D FA0.9Cs0.1SnI3 perovskite, leading to optimized p‐channel Sn2+‐perovskite TFT with a hole mobility of ≈18 cm2 V−1 s−1, a high on/off current ratio of 108, and a small subthreshold swing of 0.5 V dec−1. These TFTs also exhibit a low contact resistance of 87 Ω·cm, attributed to the improved electrode/perovskite channel interface. Furthermore, the TFTs are utilized as an electrical characterization platform to study the charge transport properties and interfacial defects using the low‐frequency noise method, providing insights into the interface properties of perovskite electronic devices.

Deuterated chloroform replaces ultra-dry chloroform to achieve high-efficient organic solar cells

Chloroform is a common and excellent solvent for preparing high-efficient organic solar cells (OSCs), however, it is toxic and poisonable chemical. In comparisons, deuterated chloroform (DC) is less toxic and costly, and particularly, it is non-poisonable chemical. In this paper, we use DC to replace ultra-dry chloroform (UC) as the processing solvent for preparation of active layers of organic solar cells. First, we selected PM6:BTP-eC9 as the basic binary and counted 100 solar cells’ data, from which comparable device performance were obtained with use of DC and UC. Interestingly, DC showed better reproducibility, superior storage under a nitrogen atmosphere and a little better performance than UC. Both DC and UC gave rise of comparable hole and electron mobilities and similar charge recombination losses. Second, we based PM6:Y6 and D18-Cl:Y6 as the binaries and similar effects were obtained from both UC and DC when counting 30 devices for each binary. Third, the universality of the use of DC for preparing high-efficient OSCs were again checked with several binary and ternary systems. In all, this study demonstrate that DC can replace UC for use in the field of OSCs.

Hydrothermally synthesized ZnFe2O4/ZnO heterojunction nanocomposites for enhanced RB dye degradation via Z-scheme photocatalysis

ZnFe2O4/ZnO nanocomposites with 1:1, 1:2, 1:3 and 1:4 wt ratios synthesized by hydrothermal method are used as a photocatalyst to degrade Rose Bengal (RB) dye. For structural investigation X-ray diffraction (XRD) and Fourier transform Infrared (FTIR) was performed. The presence of both phases corresponding to ZnFe2O4 and ZnO in XRD suggests the successful formation of a nanocomposite. Value of crystallite size varies from 25.01 nm to 18.61 nm for 1:1 to 1:4 nanocomposite. Almost spherical morphology of nanocomposite obtained through High-resolution transmission electron microscopy (HRTEM). FTIR demonstrated Zn–O and Fe–O bonds in as synthesized samples. Also, X-ray photoelectron spectroscopy (XPS) is used to detect the presence of Fe2+, Zn2+ and O2− ions in synthesized nanocomposites. In UV-DRS, values of band gap vary from 1.73 to 1.88 eV in nanocomposite as the weight ratio of ZnO increases. The formation of heterojunction is responsible for enhancing electron hole mobility. Due to this enhancement, degradation efficiency of 88% is achieved in 90 min irradiation of UV light by ZnFe2O4/ZnO (1:4) nanocomposites for RB dye followed Z-scheme mechanism. Also, the magnetization value of different nanocomposites changes from 0.9 to 0.1 emu/g. Magnetization nature is responsible for separating the catalyst from the reaction mixture after use. So, the nanocomposite can be reused which maintains the green protocol in the environment. ZnFe2O4/ZnO nanocomposite with 1:4 wt ratio can be reused up to 5 cycles. The formation of such nanocomposites can offer unique properties and advantages by combining the characteristics of both materials can lead to enhanced functionalities suitable for various applications such as catalysis, sensors, and magnetic devices.

Dually anchoring dopants in boronate ester polymer films for boosting hole mobility and stability

Dually anchoring dopants in boronate ester polymer films for boosting hole mobility and stability

Investigation of GeSe Photovoltaic Device Performance via 1-Dimensional Computational Modelling

Germanium selenide (GeSe) is a potential absorber material for thin film solar cells. However, many physical, electronic parameters and practical defect configurations that result in different effects on the performance of GeSe solar cells are not fully understood. In this study, a baseline of a GeSe thin film solar cell was designed and simulated using SCAPS-1D simulator. The physical and electronic parameters of the absorber layer is varied to investigate their effect on the performance of the solar cell. The simulation uses absorption files extracted from Xue et al. 2016 and the SCAPS-1D absorption model. Practical defect configurations are also introduced in GeSe thin film solar cells to optimize solar cell performance. Simulation results show that baseline GeSe solar cells had obtained Voc 0.62 V, Jsc 39.52 mA/cm<sup>2</sup>, FF 79.34 and ƞ 19.48%. Simulation using the SCAPS-1D absorption model achieved a more accurate JSC contour graph compared to simulation using absorption files extracted from Xue et al. 2016. The highest efficiency of 26.13% was achieved at 1.40 eV bandgap, 4.27 eV electron affinity, 10 cm2/Vs hole mobility, 1E+18 1/cm<sup>3</sup> hole concentration and 2000 nm GeSe layer thickness. For bulk defect, an increase in defect concentrations or capture cross section hole and electron (σ) reduce efficiency. For interfacial defect GeSe/CdS, total density of 1E+12 1/cm<sup>2</sup> with σ of 1E-13 cm<sup>2</sup>, total density of 1E+18 1/cm2 with σ of 1E-19 cm<sup>2</sup>, total density of 1E+16 1/cm<sup>2</sup> and 1E+18 1/cm<sup>2</sup> with σ of 1E-16 cm<sup>2</sup> have critical impact to solar cell.

Interfacial Charge Transport Enhancement of Liquid-Crystalline Polymer Transistors Enabled by Ionic Polyurethane Dielectric.

In organic field-effect transistors (OFETs) using disordered organic semiconductors, interface traps that hinder efficient charge transport, stability, anddevice performance are inevitable. Benchmark poly(9,9-dioctylfuorene-co-bithiophene) (F8T2) liquid-crystalline polymer semiconductor has been extensively investigated for organic electronic devices due to its promising combination of charge transport and light emission properties. This study demonstrates that high-capacitance single-layered ionic polyurethane (PU) dielectrics enable enhanced charge transport in F8T2 OFETs. The ionic PU dielectrics are composed of a mild blending of PU ionogel and PU solution, thereby forming a solid-state film with robust interfacial characteristics with semiconductor layer and gate electrode in OFETs and measuring high capacitance values above 10 µF cm-2 owing to the combined dipole polarization and electric double layer formation. The optimized fabricated ionic PU-gated OFETs exhibit a low-voltage operation at -3V with a remarkable hole mobility of over 5 cm2 V-1 s-1 (average = 2.50 ± 1.18 cm2 V-1 s-1), which is the highest mobility achieved so far for liquid-crystalline F8T2 OFETs. This device also provides excellent bias-stable characteristics in ambient air, exhibiting a negligible threshold voltage shift of -0.03V in the transfer curves after extended bias stress, with a reduced trap density.

Diketopyrrolopyrrole‐Dioxo‐Benzodithiophene‐Based Multifunctional Conjugated Polymers for Organic Field‐Effect Transistors and Perovskite Solar Cells

While dual‐acceptor‐type conjugated polymers have witnessed a great success in organic field‐effect transistors (OFETs), their potential multifunctionality in other optoelectronic devices has been overlooked. Herein, three conjugated polymers (DPPF‐BDD, DPPT‐BDD, and DPPSe‐BDD) comprising furan/thiophene/selenophene‐flanked diketopyrrolopyrrole (DPP) and dioxo‐benzodithiophene (BDD) as repeating units are designed, synthesized, and characterized. Modulating the chalcogen on DPP flank shows an impact on dual‐acceptor polymer optoelectronic properties. Subsequently, the potential of these polymers in both OFETs and perovskite solar cells (PSCs) either as semiconductors or as passivation materials, respectively, is investigated. Interestingly, DPPF‐BDD, DPPT‐BDD, and DPPSe‐BDD show ambipolar behavior in vacuum with hole (μh) and electron (μe) mobilities of 0.0263/0.0223, 0.0187/0.0123, and 0.0070/0.0051 cm2 V−1 s−1, respectively. Upon doping tetrabutylammonium iodide into DPPF‐BDD, DPPT‐BDD, and DPPSe‐BDD polymers, the respective OFETs show relatively higher μh and μe (0.0389/0.0503; 0.0289/0.0259; 0.0058/0.0156 cm2 V−1 s−1) than the undoped polymer OFETs. Furthermore, DPPF‐BDD‐, DPPT‐BDD‐, and DPPSe‐BDD‐incorporated (in the antisolvent treatment and PCBM electron transport layer) PSCs display maximum power conversion efficiency of 23.48%, 22.85%, and 23.35%, respectively, surpassing the control device (22.83%), which is benefited from the perovskite surface passivation and the charge extraction improvement. Overall, a new class of multifunctional DPP‐based dual‐acceptor‐type polymers that are highly compatible with OFETs and high‐performance PSCs is presented.

Enhancement of Efficiency of Perovskite Solar Cells with Hole-Selective Layers of Rationally Designed Thiazolo[5,4-d]thiazole Derivatives.

We introduce thiazolo[5,4-d]thiazole (TT)-based derivatives featuring carbazole, phenothiazine, or triphenylamine donor units as hole-selective materials to enhance the performance of wide-bandgap perovskite solar cells (PSCs). The optoelectronic properties of the materials underwent thorough evaluation and were substantially fine-tuned through deliberate molecular design. Time-of-flight hole mobility TTs ranged from 4.33 × 10-5 to 1.63 × 10-3 cm2 V-1 s-1 (at an electric field of 1.6 × 105 V cm-1). Their ionization potentials ranged from -4.93 to -5.59 eV. Using density functional theory (DFT) calculations, it has been demonstrated that S0 → S1 transitions in TTs with carbazolyl or ditert-butyl-phenothiazinyl substituents are characterized by local excitation (LE). Mixed intramolecular charge transfer (ICT) and LE occurred for compounds containing ditert-butyl carbazolyl-, dimethoxy carbazolyl-, or alkoxy-substituted triphenylamino donor moieties. The selected derivatives of TT were used for the preparation of hole-selective layers (HSL) in PSC with the structure of glass/ITO/HSLs/Cs0.18FA0.82Pb(I0.8Br0.2)3/PEAI/PC61BM/BCP/Ag. The alkoxy-substituted triphenylamino containing TT (TTP-DPA) has been demonstrated to be an effective material for HSL. Its layer also functioned well as an interlayer, improving the surface of control HSL_2PACz (i.e., reducing the surface energy of 2PACz from 66.9 to 52.4 mN m-1), thus enabling precise control over perovskite growth energy level alignment and carrier extraction/transportation at the hole-selecting contact of PSCs. 2PACz/TTP-DPA-based devices showed an optimized performance of 19.1 and 37.0% under 1-sun and 3000 K LED (1000 lx) illuminations, respectively. These values represent improvements over those achieved by bare 2PACz-based devices, which attained efficiencies of 17.4 and 32.2%, respectively. These findings highlight the promising potential of TTs for the enhancement of the efficiencies of PSCs.

Van der Waals polarity-engineered 3D integration of 2D complementary logic

Vertical three-dimensional integration of two-dimensional (2D) semiconductors holds great promise, as it offers the possibility to scale up logic layers in the z axis1–3. Indeed, vertical complementary field-effect transistors (CFETs) built with such mixed-dimensional heterostructures4,5, as well as hetero-2D layers with different carrier types6–8, have been demonstrated recently. However, so far, the lack of a controllable doping scheme (especially p-doped WSe2 (refs. 9–17) and MoS2 (refs. 11,18–28)) in 2D semiconductors, preferably in a stable and non-destructive manner, has greatly impeded the bottom-up scaling of complementary logic circuitries. Here we show that, by bringing transition metal dichalcogenides, such as MoS2, atop a van der Waals (vdW) antiferromagnetic insulator chromium oxychloride (CrOCl), the carrier polarity in MoS2 can be readily reconfigured from n- to p-type via strong vdW interfacial coupling. The consequential band alignment yields transistors with room-temperature hole mobilities up to approximately 425 cm2 V−1 s−1, on/off ratios reaching 106 and air-stable performance for over one year. Based on this approach, vertically constructed complementary logic, including inverters with 6 vdW layers, NANDs with 14 vdW layers and SRAMs with 14 vdW layers, are further demonstrated. Our findings of polarity-engineered p- and n-type 2D semiconductor channels with and without vdW intercalation are robust and universal to various materials and thus may throw light on future three-dimensional vertically integrated circuits based on 2D logic gates.

Unveiling the Doping- and Temperature-Dependent Properties of Organic Semiconductor Orthorhombic Rubrene from First Principles

Due to its large hole mobility, organic rubrene (C42H28) has attracted research questions regarding its applications in electronic devices. In this work, extensive first-principles calculations are performed to predict some temperature- and doping-dependent properties of organic semiconductor rubrene. We use density functional theory (DFT) to investigate the electronic structure, elastic and transport properties of the orthorhombic phase of the rubrene compound. The calculated band structure shows that the orthorhombic phase has a direct bandgap of 1.26 eV. From the Vickers hardness (1.080 GPa), our calculations show that orthorhombic rubrene is not a super hard material and can find useful application as a flexible semiconductor. The calculated transport inverse effective mass and electronic fitness function show that the orthorhombic rubrene crystal structure is a p-type thermoelectric material at high temperatures.

Oxygen Stoichiometry Engineering in P‐Type NiOx for High‐Performance NiO/Ga2O3 Heterostructure p‐n Diode

P‐type NiOx was employed for the fabrication of NiO/Ga2O3 p‐n diode. Addressing the challenge of low hole mobility in NiOx, an extensive investigation into the impact of oxygen stoichiometry engineering in NiOx was conducted. The meticulous optimization of the O2/Ar ratio to 30% during the sputtering process resulted in significant improvements, notably achieving enhanced hole mobility of 1.61 cm2/V·s. It led to a low specific on‐resistance of 2.79 mΩ·cm2 and a high rectification ratio of ∽1011, underscoring the efficacy of recombination transport mechanism driven by enhanced hole mobility. Detailed band alignment analysis between NiOx and Ga2O3 revealed a small band offset, with a valence band offset of 2.47 eV and a conduction band offset of 1.70 eV. It suggests a tailored modification of band alignment through the engineering the oxygen stoichiometry in NiOx, facilitating enhanced recombination conduction. The device exhibits a suprior breakdown voltage (Vb) of 2780 V and a notable Baliga’s figure of merit (BFOM) of 2.77 GW/cm2, surpassing the SiC unipolar figure of merit. The insights gained from this work are expected to inform future designs and optimizations of high‐performance Ga2O3 electronic devices.This article is protected by copyright. All rights reserved.

Hole mobility enhancement in monolayer WSe2 p-type transistors through molecular doping

Hole mobility enhancement in monolayer WSe2 p-type transistors through molecular doping

Synthesis of fluorene‐flanked diketopyrrolopyrrole‐based semiconducting polymers with thermocleavable side chains and their application in organic field effect transistors

AbstractThis study introduces the first fluorene‐flanked diketopyrrolopyrrole (FDPP)‐based semiconducting polymers, named Boc‐FDPP‐CoMs (CoM = TT or BT), synthesized via copolymerization of tert‐butoxycarbonyl (t‐Boc)‐substituted FDPP as the acceptor unit with thieno[3,2‐b]thiophene (TT) or bithiophene (BT) as the donor comonomers. The incorporation of t‐Boc groups addresses challenges related to poor solubility and polymer backbone twisting associated with the FDPP building block. While Boc‐FDPP‐CoMs demonstrate solubility in common organic solvents, facilitating favourable solution‐processability for uniform film fabrication, they exhibit significant backbone twisting, leading to poor charge transport properties. Post‐deposition thermal annealing at a mild temperature as low as 170°C conveniently removes t‐Boc groups. The resulting t‐Boc‐free copolymers, NH‐FDPP‐TT and NH‐FDPP‐BT, exhibit hole mobilities up to 5.0 × 10−3 and 2.2 × 10−3 cm2 V−1 s−1 in organic field effect transistors (OFETs), respectively, representing a substantial increase compared to their counterparts with t‐Boc groups. This study underscores a meticulously designed strategy for achieving solution solubility and backbone coplanarity through side‐chain engineering for FDPP and potentially other sterically demanding building blocks to construct high‐performance semiconducting polymers for OFETs and other applications.

O-B(F)←N Functionalized Copolymers with Delayed Fluorescence and P-Type Semiconducting Characteristics.

Conjugated polymers with integrating properties of delayed fluorescence and photovoltaic responses simultaneously are scarcely reported due to the generally contradictory requirements for molecular structures to achieve the two properties. Herein, an O-B(F)←N functionalized fused unit (M) with multiple resonance features, small energy gap between lowest singlet excited state (S1) and triplet excited state (T1) (ΔEST = 0.23eV), and delayed fluorescence (τD = 0.75 µs), is designed. Selecting three benzodithiophene (BDT) derivatives as co-units to copolymerize with M, leading to a series of O-B(F)←N embedded polymers also maintaining delayed fluorescence (τD = 0.4-0.5 µs). Moreover, p-type semiconductor characteristics are tested for these polymers with hole mobilities in the range of 10-6-10-5 cm2/Vs. Devices with obviously photovoltaic responses are prepared using these polymers as donors and Y6 as the acceptor, affording a preliminary efficiency of 5.05%. This work successfully demonstrates an effective strategy to design conjugated polymers with integrating properties of delayed fluorescence and photovoltaic performance simultaneously by introducing O-B(F)←N functional groups to polymer backbones.

Rational designing of derivatives of quinoline and iso-quinoline based hole transport materials for antimony chalcogenide and perovskite solar cells

For efficient and stable perovskite solar cells, small molecule hole transporting materials possessing robust hole mobility, hydrophobicity, and exceptional film fabrication are highly desirable. Herein, we have evaluated first-principle-based structural, electrochemical, photophysical, stability, and charge transport attributes of eight novel molecules (QT-M1 to QT-M4) and (IQT-M1-IQT-M4) attained via thiophene-spacer end-group acceptor engineering in quinoline and iso-quinoline based molecules Our results revealed that the freshly fabricated molecules showed effectual coherence in dispersion, transference, and excitation of charges, these are highly required attributes for ultrafast hole mobility. Drafted molecules showed exceptional band alignment along with the perovskite light-absorbing layer, which predicts effectual hole abstraction and transportation attributes. Comparatively, lower absorption in the visible region suggests the appropriate photophysical profile and the smaller hole reorganization energy values compared to the parent molecules estimate the ultrafast hole transport attributes. Moreover, the electron excitation states analysis predicts uniform charge transportation, reduced recombination losses, and greater charge dissociation. The high negative solvation-free energy of fabricated molecules exhibited easier film formation and processability. Overall, our results predict efficient strategies for optimizing solar cell devices with improved photophysical, electrochemical, and optoelectronic attributes.

Identification and Dynamics of Microsecond Long-Lived Charge Carriers for CsPbBr3 Perovskite Quantum Dots, Featuring Ambient Long-Term Stability.

We analyze the stability and photophysical dynamics of CsPbBr3 perovskite quantum dots (PeQDs), fabricated under mild synthetic conditions and embedded in an amorphous silica (SiOx) matrix (CsPbBr3@SiOx), underscoring their sustained performance in ambient conditions for over 300 days with minimal optical degradation. However, this stability comes at the cost of a reduced photoluminescence efficiency. Time-resolved spectroscopic analyses, including flash-photolysis time-resolved microwave conductivity and time-resolved photoluminescence, show that excitons in CsPbBr3@SiOx films decay within 2.5 ns, while charge carriers recombine over approximately 230 ns. This longevity of the charge carriers is due to photoinduced electron transfer to the SiOx matrix, enabling hole retention. The measured hole mobility in these PeQDs is 0.880 cm2 V-1 s-1, underscoring their potential in optoelectronic applications. This study highlights the role of the silica matrix in enhancing the durability of PeQDs in humid environments and modifying exciton dynamics and photoluminescence, providing valuable insights for developing robust optoelectronic materials.

Formation of an extended defect cluster in cuprous oxide

Intrinsic defects and defect clusters play an important role in the room-temperature transport of cuprous oxide. Neutralization of these defects by doping and/or modifying the synthesis process is essential to improve the room-temperature hole mobility in cuprous oxide. Toward this end, we annealed polycrystalline cuprous oxide under Cu-rich conditions, which led to the neutralization of the intrinsic acceptor defect. The concentration of both the acceptor defects ( VCu and VCusplit ) that are already present, reduces by four to five orders of magnitude. This is in accordance with the amount of possible Cu incorporation under different annealing conditions, indicating the backfilling of a large fraction of the Cu vacancies. Unforeseeably, the experimental conditions lead to the creation of yet another higher-order extended defect (3 VCu + 2Cu i ) with a defect level at ≈0.5 eV above the valence band. The formation of such a defect is also indirectly suggested by the analysis of carrier concentration vs. temperature data and first-principles calculations. Such singly ionized higher-order defects with a possibly higher capture cross-section act as more effective traps resulting in reduced hole mobility.