Optoelectronic Properties Research Articles

Tunning the optoelectronic properties of Sm3+-doped mesoporous TiO2 thin films via PVP assisted sol-gel process for solar cells

Tunning the optoelectronic properties of Sm3+-doped mesoporous TiO2 thin films via PVP assisted sol-gel process for solar cells

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.

Nanostructured Gold Interlayer‐Enhanced Self‐Powered Photodetectors for Visible and Long‐Wave Infrared Dual‐Band Applications

AbstractSelf‐powered dual‐functional detectors comprising a p‐Si/nanostructured Au/CdS sandwiched structure, which respond to the visible and long‐wave infrared dual‐band, are developed for visible light communication and passive human recognition without Fresnel lenses. Various configurations of nanostructured Au interlayers are fabricated via solid‐state dewetting, significantly enhancing the optoelectronic and pyroelectric properties of the original p‐Si/CdS system. The p‐Si/Au nanoparticles/CdS detector achieves a responsivity of 0.47 A/W, a response time of 830 ns, a −3 dB bandwidth of 0.33 MHz, and human recognition distance of up to 2 m. The improvement in optoelectronic properties is attributed to enhanced light absorption resulting from multiple internal reflections and localized surface plasmon resonance, as well as an enhanced built‐in electric field within the Au/CdS Schottky junction. The improvement in pyroelectric properties is related to enhanced polarization of CdS resulting from the interface polar symmetry, which not only improves the visible photoresponse at high pulsed light frequencies but also enables effective detection of human radiation. Additionally, the effects of body parts, vertical distance, and moving velocity on pyroelectric human recognition are systematically investigated. This work expands the diversity of multifunctional photodetectors with great potential for visible and long‐wave infrared dual‐band applications.

Cross-Transition-Dipole Stacking of Conjugated Organic Molecules: Structure, Exciton Behavior and Optoelectronic Property.

Organic conjugated molecules have gained widespread application as organic semiconductors due to their unique optoelectronic properties. The rigidity of these large conjugated structures facilitates strong intermolecular interactions, which significantly influence their properties in the solid state through various molecular arrangements. The study of the relationship among molecular arrangement, exciton behavior, and optoelectronic properties is an eternal research topic. Cross-dipole stacking is a specific molecular arrangement that demonstrates unique characteristics and has received continuous attention over the past decades. This mini-review will first discuss the unique exciton behaviors in cross-dipole stacking based on exciton models, including weak exciton coupling and suppression of Förster resonance energy transfer. These exciton behaviors, determined by molecular stacking arrangements, are fundamental to the optoelectronic properties of cross-dipole stacking systems. Next, we will introduce well-defined cross-dipole systems and summarize their design principles from a molecular structure perspective. Finally, we will present the specific optoelectronic properties of cross-dipole stacking systems and their outstanding performance, such as high solid-state luminescence, good charge carrier mobility, and significant CD/CPL. Through this mini-review, we hope to enhance the understanding of cross-dipole stacking, contributing to the construction of such systems, the exploration of excited-state behaviors, and the discovery of high-performance materials.

High-Temperature Polymorphism and Band-Gap Evolution in BaZrS3.

Barium zirconium trisulfide (BZS) is a three-dimensional (3D) perovskite with optoelectronic properties suitable for photovoltaic (PV) and light-emitting diode (LED) applications that is conventionally reported in the orthorhombic Pnma (62) symmetry. Synchrotron X-ray diffraction, thermal analysis, and Raman and absorption spectroscopy revealed three high-temperature polymorphs that appear when BZS is heated in air prior to complete oxidation (BaZrS3 + 5O2 → BaSO4 + ZrO2 + 2SO2↑) at 700 °C with the approximate stability ranges: BaZrS3 IVPnma (62)T < 400 °CBaZrS3 IIICmcm (63)400 °C ≤ T ≤ 500 °CBaZrS3 II14/mcm (140)500 °C ≤ T ≤ 700 °CDifferential scanning calorimetry (DSC) revealed exothermic features accompanying the IV → III and III → II phase changes. Furthermore, the direct band gap varied inversely with temperature with distinct energies for each polymorph (1.84 eV ≤ IV ≤ 1.65 eV; 1.65 eV ≤ III ≤ 1.54 eV; 1.54 eV ≤ II ≤ 1.52 eV). Raman spectroscopy found that polymorphic changes up to 600 °C were reversible with bands characteristic of BaZrS3 IV entirely restored upon cooling to room temperature (RT). This more complete understanding of BSZ polymorphism provides a basis for producing crystallochemical variants with enhanced optoelectronic properties under ambient conditions.

Disentangling Structural Domains in Solution‐Processed 2D Lead Halide Perovskite by Transient Absorption Spectroscopy

Abstract2D lead halide perovskites (LHPs) exhibit outstanding optoelectronic properties, making them utilized in various emerging applications. Understanding their fundamental properties is urgent for improving device performance. Here, the structural domains in 2D PEA2MAn‐1PbnI3n+1 films are studied by temperature‐dependent transient absorption (TA) measurements. For &lt;n&gt; = 1 film at low temperatures, the ground state bleach (GSB) shows obvious splitting when the high‐energy state is resonantly excited, whereas only one GSB exists under low‐energy resonant excitation, indicating that the two split energy states correspond to different structural domains. For &lt;n&gt; = 2 film, similar phenomena are observed, but the energy level difference between the two domains is decreased. With further increase of the inorganic layers number, the two domains can no longer be distinguished. In addition, by changing the organic cations, it is demonstrated that the two structural domains originate from distortions in the inorganic PbI6 octahedral frames. Finally, the possibility that the two energy states are from the formation of polaron states is ruled out by TA measurement on CsPbBr3 QDs. The results provide new insights into the structural domain properties of 2D LHPs, which directly influence the suitability of these materials for future optoelectronic devices.

Chiral-Polar Alternating Cation Intercalation-Type Perovskite Enables Sensitive Self-Driven X-ray Detection with an Ultralow Detection Limit.

Metal halide perovskites (MHPs) have shown great potential for direct X-ray detection, but achieving high sensitivity without external bias remains challenging. Chiral-polar alternating cation intercalation (ACI)-type MHPs, with excellent optoelectronic properties and a robust chirality-induced bulk photovoltaic effect (BPVE), offer a promising platform for self-driven X-ray detection. Herein, impressive self-driven X-ray detection performance was achieved by utilizing chiral-polar 2D ACI-type perovskite single crystals of (R-PPA)PAPbBr4 (1R; R-PPA = R-1-phenylpropylamine; PA = propylamine). The chiral R-PPA cations induce the crystallization of 1R in the chiral-polar space group P21, wherein its spontaneous electric polarization further induces a strong BPVE. Consequently, 1R shows remarkable radiation photovoltaics of 0.75 V, which endows its excellent self-driven X-ray detection with a high sensitivity of 417.2 μC Gy-1 cm-2 and a low detection limit of 24.1 nGy s-1, meeting the state-of-the-art level by leveraging its intrinsic photovoltaic effect. These findings highlight the huge potential of chiral-polar ACI-type MHPs in self-driven X-ray detection applications.

Perovskite Video Camera

AbstractPerovskite photodetectors (PDs) provide opportunities for high‐performance imaging owing to their excellent optoelectronic properties. However, perovskite PD‐based video rate imaging has rarely been reported due to the well‐known slow response and complex array fabrication of perovskite sensors. In this work, a perovskite video camera (PVC) based on a fast perovskite PD combined with computational imaging algorithm is fabricated. The PD has a p‐i‐n structure of FTO/PTAA/MAPbI3/PC61BM/BCP/Au. Owing to combined effects of build‐in electric field, passivation of interface layer, and short carrier transport distance, the proposed PD demonstrates fast response speed of 0.275/0.39 µs (rise/fall). With the help of the computational imaging algorithm, complex array fabrication is bypassed, and successfully demonstrates video rate imaging of a fast‐moving ball with 25 frame s−1 using this single PD. Therefore, this study can call this PVC and believes that the camera provides a new application scenario for perovskite and other emerging optoelectronic materials.

Perovskite in Triboelectric Nanogenerator and the Hybrid Energy Collection System.

In the context of escalating energy demands and environmental sustainability, the paradigm of global energy systems is undergoing a transformative shift to innovative and reliable energy-harvesting techniques ranging from solar cells to triboelectric nanogenerators (TENGs) to hybrid energy systems, where a fever in the study of perovskite materials has been set off due to the excellent optoelectronic properties and defect tolerance features. This review begins with the basic properties of perovskite materials and the fundamentals of TENGs, including their working principles and general developing strategy, then delves into the key role of perovskite materials in promoting TENG-based hybrid technologies in terms of energy conversion. While spotlighting the coupling of triboelectric-optoelectronic effects in harnessing energy from a variety of sources, thereby transcending the limitations inherent to single-source energy systems, this review pays special attention to the strategic incorporation of perovskite materials into TENGs and TENG-based energy converting systems, which heralds a new frontier in enhancing efficiency, stability, and adaptability. At the end, this review highlights the remaining challenges such as stability, efficiency, and functionality for applications in TENG-based energy-harvesting systems, aiming to provide a comprehensive overview of the current landscape and the prospective trajectory of the role of perovskite materials in TENG-based energy-harvesting technologies within the renewable energy sector.

Photoinduced Electron-Nuclear Dynamics of Fullerene and Its Monolayer Networks in Solvated Environments.

The recently synthesized monolayer fullerene network in a quasi-hexagonal phase (qHP-C60) exhibits superior electron mobility and optoelectronic properties compared to molecular fullerene (C60), making it highly promising for a variety of applications. However, the microscopic carrier dynamics of qHP-C60 remain unclear, particularly in realistic environments, which are of significant importance for applications in optoelectronic devices. Unfortunately, traditional ab initio methods are prohibitive for capturing the real-time carrier dynamics of such large systems due to their high computational cost. In this work, we present the first real-time electron-nuclear dynamics study of qHP-C60 using velocity-gauge density functional tight binding, which enables us to perform several picoseconds of excited-state electron-nuclear dynamics simulations for nanoscale systems with periodic boundary conditions. When applied to C60, qHP-C60, and their solvated counterparts, we demonstrate that water/moisture significantly increases the electron-hole recombination time in C60 but has little impact on qHP-C60. Our excited-state electron-nuclear dynamics calculations show that qHP-C60 is extremely unique and enable exploration of time-resolved dynamics for understanding excited-state processes of large systems in complex, solvated environments.

Modulation of Energy Band Positions in Sb2S3 Thin Films for Enhanced Photovoltaic Performance of FTO/TiO2/Sb2S3/P3HT/Au Solar Cell

Antimony sulfide (Sb2S3) has the potential as an absorber material in photovoltaics due to its suitable bandgap and favorable optoelectronic properties. However, its energy band positions are not extensively explored which are essential for effective charge separation and transfer. This study examines the energy band positions of Sb2S3 thin films as a function of annealing temperature. Sb2S3 thin films are grown by a combination of successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) method to enhance the crystallinity, tune the bandgap, and overall quality of Sb2S3 films to enhance the photovoltaic performance. Optical bandgap decreases from 2.41 to 1.67 eV from the as‐deposited films to annealed at 300 °C due to changes in interatomic distances. Energy band positions of Sb2S3 films are measured both by cost‐effective electrochemical cyclic voltammetry and Mott–Schottky analysis and validated the findings using ultraviolet photoelectron spectroscopy (UPS). The conductivity of Sb2S3 is found to be n‐type. Thin‐film solar cells are then fabricated by employing Sb2S3 as an absorber layer in an FTO/TiO2/Sb2S3/P3HT/Au structure, achieving an enhanced power conversion efficiency, increasing from 0.4 to 2.8% after annealing. These findings demonstrate the potential of Sb2S3 as a low‐cost absorber material for thin‐film photovoltaics.

Preparation of Single‐Crystal MoS2 Nanotubes and 1D Van der Waals Heterostructures

AbstractSingle‐crystal MoS2 nanotubes possess outstanding electronic and optoelectronic properties. However, previous attempts to synthesize MoS2 nanotubes are hindered by poor crystallinity and the high strain energy required to roll a sheet with three atomic layers into a tubular structure. Here, the confined template growth of well‐crystallized MoS2 nanotubes encapsulated within carbon nanotubes, forming 1D van der Waals heterostructures, is reported. The growth of MoS2 nanotubes is catalyzed by iron carbide. CNTs serve as nanoreactors and structurally confined templates, ensuring the growth of fine MoS2 nanotubes. Water vapor is employed to manipulate the structure and morphology of resultant MoS2. Free‐standing MoS2 nanotubes are obtained by removing outer CNTs with gentle plasma etching. This method demonstrate the power of coupling the catalytic effect and the space confinement in the growth of high‐quality MoS2 nanotubes, which may become a common strategy for the preparation of general 1D nanostructures of various transition metal dichalcogenides and other materials.

Correction to: Density functional study of structural and optoelectronic properties of SnTe: rocksalt and orthorhombic phases

Correction to: Density functional study of structural and optoelectronic properties of SnTe: rocksalt and orthorhombic phases

Photoconduction in 2D Single‐Crystal Hybrid Perovskites

AbstractSingle‐crystal hybrid perovskites represent an emerging class of next‐generation semiconductors due to their excellent and tunable optoelectronic properties, along with a solution‐based, low‐temperature growth process. 2D single‐crystal hybrid perovskites are especially promising as their long‐range ordered multiple quantum well structure induces many peculiar properties, such as large exciton binding energy, large in‐plane conductivity, and improved environmental stability, which make them suitable for low‐dimensional optoelectronics applications and fundamental studies. Herein, the structural properties, morphology, and optoelectronic behavior of 2D thin film phenethylammonium lead iodide (PEA2PbI4) single‐crystals, synthesized using the space‐confined growth technique are explored. A planar device is fabricated and its spectral photoresponse is studied under broadband supercontinuum white light. Remarkably, the device exhibits an ultra‐low dark current (10−14 A), indicative of low defect density and suppressed ion migration. Under white light, the current increases linearly with the incident power, up to a factor of 105, and the device achieves a specific detectivity of 109 Jones. The temperature and wavelength dependence of the photocurrent suggests the dissociation of excitons as one of the main mechanisms affecting photoconduction. Furthermore, stability under air exposure and illumination turns out to be remarkable.

First-principles investigation of structural, mechanical, and electronic properties of AMgX3 (A=Ga, In, Tl, and X=Cl, Br, I) perovskites for optoelectronic applications

Abstract Metal-halide perovskites have emerged as a revolutionary material in solar energy technology, offering exceptional light-harvesting efficiency, eco-friendly characteristics, and low production costs. These materials are paving the way for next-generation photovoltaic devices with their outstanding optoelectronic properties and scalability for commercial applications. To determine the various features of the halide perovskites AMgX3 (where A stands for Ga, In, Tl, and X for Cl, Br, and I), we utilized DFT with the (Generalized Gradient Approximation) GGA-PBE (Perdew–Burke–Ernzerhof) exchange and correlation approximation to examine the structural, mechanical, electronic, and optical behaviors of the perovskite materials. Structurally, these materials exhibit cubic stability, vital for high-performance durability in photovoltaic devices. Mechanically, the calculated elastic constants verify their strength, suitable for environments where mechanical stability is critical, such as in aerospace electronics. The band gap range (1.22–3.69 eV) shows how versatile the materials are. TlMgI3 is suitable for infrared (IR) detection, whereas GaMgCl3 and InMgCl3 are optimal for ultraviolet (UV) applications. These findings support applications from IR sensors to UV photo detectors. The compounds’ optical properties, such as their high absorption coefficients, dielectric constants, and reflectivity, show how well they can collect and send light, which is important for solar cells and LEDs. The mechanical and optoelectronic properties collectively enhance their suitability for photonic and thermoelectric devices, offering scalable solutions for renewable energy and advanced photonics applications.

An Aqueous Processed Photosensitive Bilayer van der Waals Thin Film for Flexible Neuromorphic Vision

AbstractPrinting colloidal ink of semiconductor nanocrystals, particularly 2D nanosheets, facilitates the generation of van der Waal's thin films (vdWTFs) with inherent flexibility and optoelectronic properties, ideal for wearable intelligence devices, such as bionic vision. Several intricate strategies, such as mechanical/electrochemical exfoliation and pulsed laser/chemical vapor, have been devised for producing solvent‐dispersed nanosheets and corresponding vdWTFs; achieving efficient preparation via more environmentally friendly processes remains a challenge. Here, an ecofriendly aqueous approach for crafting vdWTF, relying on a gentle self‐assembly C8‐BTBT nanosheet aqueous ink, is demonstrated. The resulting vdWTF features a bilayer heterostructure, wherein a crystalline C8‐BTBT nanosheet layer is staggeringly stacked atop a graphene oxide (GO) film. This configuration allows the sliding of the staggered 2D nanosheets, accommodating local tension and compression, thereby averting film breakage and ensuring desirable flexibility. Further, by harnessing the natural photosensitivity of C8‐BTBT and the charge‐trapping capabilities of GO component, the heterostructured bilayer vdWTFs confer exceptional photoperception and intrinsic persistent photoconductivity effects upon their flexible planar devices. These attributes enable the emulation of bio‐visual behaviors such as short/long‐term memory, light adaptation, reinforcement learning, and image recognition.

Chloride Engineering for Boosting Perovskite Photovoltaics: Impact on Precursor Coordination, Crystallization, and Film Quality.

Perovskite solar cells (PSCs) have seen rapid advancements over the past decade, driven by their exceptional optoelectronic properties and high power conversion efficiencies. Cl-based additives strategy has significantly contributed to these advancements by enhancing crystallinity, improving preferred orientation, and optimizing the surface morphology of perovskite films. This review provides a comprehensive summary of recent advancements and insights into the critical role of Cl-based additives in perovskite photovoltaics, focusing on the mechanisms behind Cl incorporation and its effects on film and device performance. First, the impact of Cl on precursor solution coordination and colloidal characteristics is discussed. Then, how Cl-based additives influence the phase transitions of perovskites, including methylammonium lead iodide (MAPbI3), formamidinium lead iodide (FAPbI3), and 2D perovskites is examined. Furthermore, the impact of Cl-based interfacial treatments on perovskite film quality is explored. Based on these insights, the overall impact of Cl treatments is also reviewed on the properties of perovskite films. Finally, a brief overview of the remaining challenges and future perspectives are provided to guide ongoing research efforts toward optimizing Cl additive engineering for high-performance PSCs.

Unraveling the Configuration Modulation in Spiro‐Based Through‐Space Charge Transfer Materials

AbstractThermally activated delayed fluorescence (TADF) materials hold promise for optoelectronic applications. Among various design strategies, through‐space charge transfer (TSCT) systems offer the potential for enhanced performance. However, the relationship between molecular configuration and TSCT properties remains unclear compared to traditional through‐band charge transfer materials. In this study, we investigated the influence of spatial configuration on TSCT features and electronic properties of triplet excited states in these TSCT materials. By manipulating the spatial arrangement between donor and acceptor segments using different spiro skeletons, a series of TSCT materials (DMB2‐DMB5) was synthesized. Together with the parent molecule, DM‐B, these materials exhibited completely different TADF characteristics, demonstrating the impact of spatial arrangements on their optoelectronic properties. Thus, the external quantum efficiency of these materials ranged from as high as 28.0 % (DMB2) to as low as 3.6 % (DMB5) due to variations in their TADF characteristics. Our findings highlight the significance of spatial configuration, beyond distance alone, in influencing TSCT properties when donor and acceptor segments are sufficiently close. This insight provides valuable guidance for developing advanced TSCT materials and advancing TADF systems with improved performance and functionality.

Role of grain boundary passivation in the enhancement of efficiency of copper chalcogenides thin film photovoltaic devices: A schematic review

Photovoltaic devices are expected to display peak performance if fabricated with perfect single crystals. Since surfaces break the periodicity of a single crystal, there are regions of defects, which give rise to states inside the forbidden energy gap. In polycrystalline thin films, the main structural defect is the grain boundary. The presence of grain boundaries affects the optical absorption, carrier mobility and lifetime of the semiconductor. This review focuses on grain boundary passivation in thin film photovoltaic devices based on copper chalcogenides. Achieving enhanced performance in copper chalcogenide thin film Photovoltaic devices requires effective grain boundary passivation. This approach aims to mitigate the adverse effects of grain boundaries on the optoelectronic properties of the material, leading to improved efficiency and stability in Photovoltaic devices. The abstract discusses recent developments, methodologies and outcomes related to grain boundary passivation strategies, shedding light on their significance in advancing the performance of copper chalcogenide thin film Photovoltaic devices. The exploration of grain boundary passivation in this context contributes valuable insights to the ongoing efforts in optimizing the performance of thin film Photovoltaic technologies.

The Synthesis, Characterization, and Theoretical Study of Ruthenium (II) Polypyridyl Oligomer Hybrid Structures with Reduced Graphene Oxide for Enhanced Optoelectronic Applications.

π-conjugated polymers are arguably one of the most exciting classes of materials and have attracted substantial attention due to their unique optical and electronic properties. The introduction of transition metals into conjugated polymers tunes the optoelectronic properties of these metallopolymers, which may improve their performance in device applications. Graphene and reduced graphene oxide (RGO) derivatives are interesting materials with a unique structure and outstanding properties. The present work reports an investigation of three hybrid RGO and π-conjugated oligomers that contain ruthenium polypyridyl chromophores serving as models to provide molecular-level insight for the corresponding transition-metal-containing conjugated polymers.