Optoelectrical Applications Research Articles

Impact of TBAI Doping on the Optical and Dielectric Features of PVC/MoO3/NiMoO4/PANI Polymer Composite for Optoelectronic and Energy Storage Applications

Poly (vinyl chloride, PVC)/MoO3/NiMoO4/polyaniline (PANI)/x wt% tetrabutylammonium iodide (TBAI) polymers were formed using casting and hydrothermal methods. The present study examined the nanocomposites’ structural, electrical, and optical features comprising PVC/MoO3/NiMoO4/PANI/x wt%TBAI polymers. X-ray diffraction and scanning electron microscopy were used to investigate the structure and morphology of different samples. The influence of different amounts of TBAI on the linear and nonlinear optical features of PVC/MoO3/NiMoO4/PANI/x wt%TBAI polymers was explored. Adding MoO3/NiMoO4/PANI.TBAI reduced the direct and indirect optical band gaps to their minimum values (3.88, 3.04) eV and (3.58, 2.13) eV, respectively. Doped polymer with MoO3/NiMoO4 has the highest refractive index value. Only PVC filled with MoO3/NiMoO4 exhibits the highest non-linear optical parameters within the visible range. The fluorescence intensity and emitted colors influenced by the kind of dopant. The dielectric constant and ac conductivity values of the host polymer were affected by the amount of TBAI. The maximum energy density value was observed in PVC/MoO3/NiMoO4/PANI/10 wt%TBAI polymer. The Cole-Cole plot demonstrated an irregular shift for doped samples relative to the undoped. The obtained results nominated the nanocomposite films of PVC/MoO3/NiMoO4/PANI/x wt%TBAI to be used in diverse electric and optoelectrical applications.

Tuning of optical, thermodynamic, and thermoelectric properties of Cs2CuBiX6 (X = Cl, Br, I) halide perovskites for solar cells and energy harvesting applications

The double perovskites are outstanding materials for solar cells and transport applications to clean harvest energy. Therefore, the Cs2CuBiX6 (X = Cl, Br, I) are discussed comprehensively for energy harvesting by modified Becke and Johnson (mBJ) potential. The studied DPs fit the structural, mechanical, and dynamic stability scale by tolerance factor, Born–Huang criteria, and phonon dispersion band structures. The band gaps (1.20, 1.0, 0.70) eV for (Cl, Br, I) based DPs ensure the Cs2CuBiCl6 has an absorption band in the visible region while Cs2CuBiBr6 and Cs2CuBiI6 has an absorption band in the infrared region. Heavy elements’ spin–orbit coupling effect (Cs, Bi) reduces the band gap to 0.08 eV. Thermoelectric behavior regarding the merit scale against dopant carriers and temperature has been elaborated. The ultralow lattice thermal conductivity, large Debye temperature, hardness, and melting temperature increase their implication for thermoelectric and other thermodynamic applications. The variation in band gap makes them important for diverse optoelectric and thermoelectric applications. The Cs2CuBiCl6 with a band gap of 1.20 eV is suitable for solar cells, while Cs2CuBiBr6 and Cs2CuBiI6 with band gaps of 1.0 eV and 0.70 eV are significant for thermoelectric generators.

Enhance Carrier Diffusion of Monolayer MoSe2 by Interface Engineering.

Two-dimensional materials hold great potentials for beyond-CMOS (complementary metal-oxide-semiconductor) electronical and optoelectrical applications, and the development of field effect transistors (FET) with excellent performance using such materials is of particular interest. How to improve the performance of devices thus becomes an urgent issue. The performance of FETs depends greatly on the intrinsic electrical properties of the channel materials, meanwhile the device interface quality, such as extrinsic scattering of charged impurities, charge traps, and substrate surface roughness have a great influence on the performance. In this paper, the impact of the interface quality on the carrier diffusion behaviors of monolayer (ML) MoSe2 has been investigated by using an in situ ultrafast laser technique to avoid the surface contamination during device fabrication process. Two types of self-assembled monolayers (SAMs) are introduced to modify the gate dielectric surface through an interface engineering approach to obtain chemical-stable interfaces. The results showed that the transport properties of ML MoSe2 were enhanced after interface engineering, for example, the carrier mobility of ML MoSe2 was improved from ∼59.4 to ∼166.5 cm2 V-1 s-1 after the SAM modification. Meanwhile, the photocarrier dynamics of ML MoSe2 before and after interfacial engineering were also carefully studied. Our studies provide a feasible method for improving the carrier diffusion behaviors of such materials, and making them suited for application in future integrated circuit.

Bias‐Switchable Dual‐Mode Organic Photodetector with High Operational Stability Using Self‐Trapped Cs3Cu2I5 Interfacial Layer

AbstractConventional photovoltaic (PV)‐photodetectors are hard to detect fainted signals, while photomultiplication (PM)‐capable devices indispensable for detecting weak light and are prone to degrade under strong light illumination and large bias, and it is urgent to realize highly efficient integrated detecting system with both PM and PV operation modes. In this work, one lead‐free Cs3Cu2I5 nanocrystals with self‐trapping exciton nature was introduced as interfacial layer adjacent to bulk and layer‐by‐layer heterojunction structure, and corresponding organic photodetectors with bias‐switchable dual modes are demonstrated. The fabricated device exhibits low operating bias (0 V for PV mode and 0.8 V for PM mode), high specific detectivity (~1013 Jones), fast response speed as low as 1.59 μs, large bandwidth over 0.2 MHz and long‐term operational stability last for 4 months in ambient condition. This synergy strategy also validated in different materials and device architectures, providing a convenient and scalable production process to develop highly efficient bias‐switchable multi‐functional organic optoelectrical applications.

Bias-Switchable Dual-Mode Organic Photodetector with High Operational Stability Using Self-Trapped Cs3Cu2I5 Interfacial Layer.

Conventional photovoltaic (PV)-photodetectors are hard to detect fainted signals, while photomultiplication (PM)-capable devices indispensable for detecting weak light and are prone to degrade under strong light illumination and large bias, and it is urgent to realize highly efficient integrated detecting system with both PM and PV operation modes. In this work, one lead-free Cs3Cu2I5 nanocrystals with self-trapping exciton nature was introduced as interfacial layer adjacent to bulk and layer-by-layer heterojunction structure, and corresponding organic photodetectors with bias-switchable dual modes are demonstrated. The fabricated device exhibits low operating bias (0 V for PV mode and 0.8 V for PM mode), high specific detectivity (~1013 Jones), fast response speed as low as 1.59 μs, large bandwidth over 0.2 MHz and long-term operational stability last for 4 months in ambient condition. This synergy strategy also validated in different materials and device architectures, providing a convenient and scalable production process to develop highly efficient bias-switchable multi-functional organic optoelectrical applications.

Chiral Covalent Organic Framework Films with Enhanced Photoelectrical Performances.

The desirable superimposed stacking of two-dimensional covalent organic frameworks (2D COFs) benefits out-of-plane charge transfer, whereas the actual stacking deviation cannot leverage the potential of 2D COFs for optoelectrical applications. Herein, we report a chirality-induced strategy to control the parallel AA-stacking sequence for the β-ketoenamine-linked COF film supported on a FTO substrate. The resulting chiral modules are periodically distributed at the framework node, ensuring identical mirrored configurations of layers for parallel stacking. Such unique architectonics exhibit the prolonged charge carrier lifetime, fast charge-transfer dynamics, and ultrahigh electron collection efficiency, thereby allowing for the excellent photocurrent response of 38 μA/cm2 at 0.25 V (vs RHE). The origin of superior performances lies in the intensified exciton gradient distribution and electron density for photoinduced electron-hole dissociation and charge transfer, in stark contrast to achiral analogues. This study highlights the stacking sequence regulated by chiral nanoarchitectonics and promises great potential of chiral COFs in photoelectrical catalysis.

Rapidly Grown Hexagonal Organic Microtubes Using Ionic Liquids for an Enhanced Optical Waveguide Effect

AbstractAn optical waveguide that transmits the electromagnetic waves is a critical component for various optoelectrical applications including integrated optical circuits and optical communications. Among many, the 1D tubular optical waveguide structure enables efficient distant energy transfer via mode selection within the optical microcavity. However, its application is limited due to the complicated fabrication process. Herein, hexagonal tris(8‐hydroxyquinoline) aluminum (Alq3) microtubes with an average longitudinal length of ≈15 µm are self‐assembled within few minutes by utilizing 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIMBF4) ionic liquids. The swift fabrication is enabled by the high electron affinity of BMIMBF4 that forms hexagonal microrods. Also, BMIMBF4 ionic liquid etches the central region of micorods during its growth, forming microtubes with a wall thickness of ≈650 nm. The fabricated Alq3 microtubes show significantly improved waveguide characteristics with reduced optical loss coefficient (0.054 µm−1) compared to that of microrods (0.271 µm−1). The demonstrated method to fabricate Alq3 microtubes with ionic liquid is an efficient approach to utilize organic microstructures as an optoelectrical components for advanced optical communications.

Nonvolatile Isomorphic Valence Transition in SmTe Films.

The burgeoning field of optoelectronic devices necessitates a mechanism that gives rise to a large contrast in the electrical and optical properties. A SmTe film with a NaCl-type structure demonstrates significant differences in resistivity (over 105) and band gap (approximately 1.45 eV) between as-deposited and annealed films, even in the absence of a structural transition. The change in the electronic structure and accompanying physical properties is attributed to a rigid-band shift triggered by a valence transition (VT) between Sm2+ and Sm3+. The stress field within the SmTe film appears closely tied to the mixed valence state of Sm, suggesting that stress is a driving force in this VT. By mixing the valence states, the formation energy of the low-resistive state decreases, providing nonvolatility. Moreover, the valence state of Sm can be regulated through annealing and device-operation processes, such as applying voltage and current pulses. This investigation introduces an approach to developing semiconductor materials for optoelectrical applications.

Synthesis of UV-resistant and colorless polyimide films for optoelectrical applications

Due to their excellent mechanical properties and intrinsic flexibility, polyimides (PIs) are promising candidates for optoelectrical applications under harsh conditions such as flexible organic solar cells as well as flexible smart windows, etc. Much progress has been made on their optical transmittance; however, there remain significant concerns about their environmental stability, particularly their UV resistance. Herein, 4 types of colorless polyimides (CPIs) with different molecular structures containing trifluoromethyl, ethers, or fluorenes are carefully designed, and the dependence of their UV resistance on structures is explored systematically. It is found that the introduction of isopropylidene, ethers and fluorenes effectively enhances the UV resistance of CPI and its initial performance (optical transparency, thermal stability, and toughness) simultaneously as a result of the subtle manipulation of the conjugation structures. Specifically, the optimized polyimide film shows decent optical properties (T550 nm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{550{\\rm{nm}}}$$\\end{document} ~ 88%, yellowness index ~3.26), and thermal stability (T5%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{5 \\% }$$\\end{document} ~ 503 °C in N2 atmosphere, Tg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{{\\rm{g}}}$$\\end{document} ~ 312 °C). Moreover, after high-intensity UV irradiation, CPI not only maintains over 90% of mechanical properties but also retains excellent optical properties (T550 nm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{550{\\rm{nm}}}$$\\end{document} ~ 88%) and thermal stability (T5%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{5 \\% }$$\\end{document} ~ 506 °C). The design strategy paves the way for enhancing the durability of PIs for energy conversion and electronic applications resisting harsh conditions.

Hybridized Luminescent Lanthanide Super Crystals Used as Spectral Convertors to Increase Photoconductivity in Opto-Electronic Devices

Discovering new forms of energy has been essential for the innovation of more efficient technologies in the future and is a phenomenon in optical and scientific industries worldwide. A solar cell converts electromagnetic radiation or artificial light into energy due to the photovoltaic effect. Solar cell efficiency has increased over the years due to different device material and design. Lanthanide elements are the interest for solar cell research due to their absorption of lost photons by utilizing the photoelectric effect. Lanthanide super crystals can increase photonic interactions and have the possibility of enhancing photoconductivity to create more efficient solar cells. In this research Ln3+ complexes will be used as spectral converters to increase photonic activity within inorganic solar cell devices. The research objective of this project is to enhance photonic absorption within existing inorganic solar cells from the ULTRAVIOLET(UV)-VISIBLE(VIS)-INFRARED(IR) electromagnetic spectrum. Overall, we were able to develop efficient light absorbing UC lanthanide metamaterials for opto-electric device applications.

PbSe/PbS Core/Shell Nanoplatelets with Enhanced Stability and Photoelectric Properties

Lead chalcogenide nanoplatelets (NPLs) have emerged as a promising material for devices operating in the near IR and IR spectrum region. Here, we first apply the cation exchange method to PbSe/PbS core/shell NPL synthesis. The shell growth enhances NPL colloidal and environmental stability, and passivates surface trap states, preserving the main core physical properties. To prove the great potential for optoelectrical applications, we fabricate a photoconductor using PbSe/PbS NPLs. The device demonstrates enhanced conductivity and responsivity with fast rise and fall times, resulting in a 13 kHz bandwidth. The carrier transport was investigated with the field effect transistor method, showing p-type conductivity with charge mobility of 1.26 × 10−2 cm2·V−1·s−1.

Modification and development in the microstructure of carboxy methyl cellulose-TiO2/Cr2O3 nanocomposites films for optoelectrical applications

Carboxymethyl cellulose (CMC) has been encapsulated with TiO2 and Cr2O3 nanoparticles via laser ablation route. The prepared films have different nanoparticle concentrations depending on the ablation time. The films were performed via XRD, FTIR, TGA, UV, and AC conductivity. XRD patterns reveal the presence of amorphous characteristics in chitosan (Cs), as indicated by the appearance of a broad hump at 2θ = 23.49°. However, upon doping Carboxymethyl cellulose with TiO2 and Cr2O3 NPs, this hump vanishes. The FT-IR spectra analysis demonstrates decreasing in the intensities of certain bands when compared to the spectrum of the pure CMC. This observation approved the complexation between CMC and TiO2/Cr2O3 NPs. The TGA results show that CMC-based samples doped with TiO2/Cr2O3 NPs exhibit superior thermal stability compared to the pure CMC sample. Moreover, the direct band gap decreased from 5.71 to 3.44 eV by increasing the concentration of the doping. Furthermore, the indirect band gap was calculated optically and showed a reduce in band gap from 4.79 to 1.55 eV. The inclusion of TiO2/Cr2O3 NPs significantly increased the ionic conductivity of the composite films CMC-TiO2/Cr2O3 NPs, reaching a maximum value of 5.2 10−9 S/c. Electrical analysis obtains that as the concentration of Cr2O3 NPs nanoparticles raised, an enhancement in the conductivity of the resulting CMC/TiO2/Cr2O3 nano-composite films. The results provide strong evidence that the CMC-TiO2/Cr2O3 possess exceptional thermal and electronic properties. This makes them a compelling candidate for use in energy storage applications.

Structural, optical, and electrical enhancement of polyethylene oxide (PEO) and sodium alginate (NaAlg) through embedding silver nanoparticles (Ag NP) for optoelectrical applications

Structural, optical, and electrical enhancement of polyethylene oxide (PEO) and sodium alginate (NaAlg) through embedding silver nanoparticles (Ag NP) for optoelectrical applications

Scalable Bilayer MoS2‐Based Vertically Inverted p–i–n Light‐Emitting Diodes

AbstractHerein, a vertically inverted p–i–n architecture of light‐emitting diodes (LEDs) is designed for manufacturing feasibility and demonstrated scalable bilayer MoS2‐based LEDs. A 4 inch scale bilayer MoS2 is prepared by a two‐step growth method allocating the pre‐deposition of a few‐nm thick metal film and post‐sulfurization. To apply bilayer MoS2 for an active layer in LEDs, the film is transferred over ZnO nanoparticle layers, an electron transfer layer, and then the rest of the LED components are constructed by thermal deposition. This vertically inverted LED architecture allows individual organic or inorganic components to incorporate without degradation during the wet‐transfer process and transfer electron or hole carriers across separate layers, resulting in efficient radiative recombination in the MoS2 emitting layer. MoS2‐based LEDs exhibit electroluminescence of ≈5.41 cd m−2 throughout four active areas of 6.25 mm2 at a driving voltage of 7 V. Therefore, this achievement can overcome the drawbacks of existing transition metal dichalcogenides (TMDs)‐based optoelectrical applications and extend its potential in various fields, such as flexible, ultrathin, or transparent displays.

Enhancement of the optical and electrical properties of poly ethyl methacrylate/polyvinyl chloride-zinc sulphide (PEMA/PVC@ZnS) ternary nanocomposite films

Our research introduces a novel ternary nanocomposite consisting of polyethyl methacrylate/polyvinyl chloride-Zinc sulphide nanoparticles (PEMA/PVC@ZnS). Zinc sulphide (ZnS) nanoparticles were produced via a chemical method and then dispersed at different concentrations (0.02, 0.05, 0.08, and 0.1 wt%) in a single step within the PEMA/PVC blend. The resulting PEMA/PVC@ZnS nanocomposite films were analyzed to investigate their spectroscopic and electrical properties. The dielectric parameters of the samples were also studied in detail. X-ray diffraction (XRD) data indicated an increase in the amorphous region and demonstrated the interaction between ZnS and PEMA/PVC. Fourier transform infrared (FT-IR) results confirmed the specific interactions in PEMA/PVC@ZnS nanocomposites. The synthesized films showed a distinct absorption band at 432 nm, which was attributed to the ZnS surface plasmon resonance. As the concentration of ZnS in PEMA/PVC increased, the band gap energies decreased for both direct and forbidden transitions. Optical parameters such as the extinction coefficient (k), refractive index (n), dielectric constants (ε′ and ε''), optical conductivity (σ(opt.), and photoluminescence (PL) were also studied. The values of dielectric permittivity and dielectric modulus from AC measurement of PEMA/PVC@ZnS nanocomposite films increased with increasing ZnS content. The data suggest that PEMA/PVC@ZnS nanocomposite films exhibit excellent optical and electronic properties, making them suitable for use in various electric and optoelectric applications.

Nanoscale patterning on layered MoS2 with stacking-dependent morphologies and optical tunning for phototransistor applications

Nanoscale patterning has attracted considerable interest as a novel engineering technology for two-dimensional (2D) nanomaterials for various applications such as electronics, sensors, and catalysts. However, research on nanopatterning technologies that reflect the unique structural and electrical characteristics of 2D nanomaterials remains insufficient. In this study, we present a nanoscale patterning of two different polygons on layered molybdenum disulfide (MoS2), where the nanostructures are controlled by the stacking structure of MoS2. We investigate the dependence of nanopore edge stability on the stacking structure of MoS2 using density functional theory calculations and find the different geometric effects of the two nanopatterns on the band-structure modulation of semiconducting MoS2. Consistent with the theoretical calculations, we fabricate nanoporous MoS2 with hexagonal nanopores for AA’ and triangular nanopores for AB stacked MoS2 films. The AA’ MoS2 has narrow nanoribbons between the two hexagonal nanopores, resulting in a lateral quantum confinement effect, whereas the edge exposure effect is more dominant for the bandgap increase in the triangular nanoporous structure. Nanopatterns contribute to generating in-gap state of MoS2, significantly enhancing the photoelectrical characteristics of MoS2 phototransistors. Especially, the photogating effect is higher for AA’ MoS2 phototransistors with hexagonal nanoholes than AB MoS2 with triangular nanoholes. This study provides new insights into nanoscale patterning and band structure engineering of layered 2D materials for various optoelectrical applications.

Controllable spin splitting in 2D ferroelectric few-layer γ-GeSe

γ-GeSe is a new type of layered bulk material that was recently successfully synthesized. By means of density functional theory first-principles calculations, we systematically studied the physical properties of two-dimensional (2D) few-layer γ-GeSe. It is found that few-layer γ-GeSe are semiconductors with band gaps decreasing with increasing layer number; and 2D γ-GeSe with layer number n ⩾ 2 are ferroelectric with rather low transition barriers, consistent with the sliding ferroelectric mechanism. Particularly, spin–orbit coupling induced spin splitting is observed at the top of valence band, which can be switched by the ferroelectric reversal; furthermore, their negative piezoelectricity also enables the regulation of spin splitting by strain. Finally, excellent optical absorption was also revealed. These intriguing properties make 2D few-layer γ-GeSe promising in spintronic and optoelectric applications.

Effect of low energy cesium ion irradiation on vanadium oxide: Structural and spectroscopic study

Vanadium di-oxide (VO2) and vanadium tetra oxide (V2O4) powders are exposed to cesium (Cs) ion irradiation using Pelletron accelerator. The energy of the Cs ions ranges from 0.2 keV to 5 keV. Mass spectroscopic data from the accelerator is plotted for various energy ranges. Un-irradiated samples and Cs ion irradiated samples are characterized by using x-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectroscopy and four-point probe method. XRD analysis showed improved VO2 crystallinity after ion irradiation. The V2O4 sample shows amorphous behavior after ion irradiation. Dislocation density and tolerance are calculated to explore structure distortion after ion irradiation. Raman spectroscopy reveals vibrational and rotational modes of bonding with oxygen and vanadium. SEM results explain the reduction in agglomeration after Cs ion irradiation. The resistivity of un-irradiated and irradiated (VO2 and V2O4) samples is calculated by four-point probe method. The resistivity of vanadium oxide is decreased after Cs ion irradiation to make it a potential candidate for optoelectrical applications.

Modulating the Function of GeAs/ReS2 van der Waals Heterojunction with its Potential Application for Short-Wave Infrared and Polarization-Sensitive Photodetection.

Van der Waals heterojunction (vdWs) of 2D materials with integrated or extended superior characteristics, opening up new opportunities in functional electronic and optoelectric device applications. Exploring methods to achieve multifunctional vdWs heterojunction devices is one of the most promising prospects in this area. Herein, a diverse function of forward rectifying diode, Zener tunneling diode, and backward rectifying diodes are realized in GeAs/ReS2 heterojunction by modulating the doping level of GeAs. The tunneling diode presents an interesting trend forward negative differential resistance (NDR) behavior which may facilitate the application of multi-value logic. More importantly, the GeAs/ReS2 forward rectifying diode exhibits highly sensitive photodetection in the wide-spectrum range up to 1550nm corresponding to a short-wave infrared (SWIR) region. In addition, as two strong anisotropic 2D materials of GeAs and ReS2 , the heterojunction exhibits strong polarization-sensitive photodetection behavior with a dichroic photocurrent ratio of 1.7. This work provides an effective strategy to achieve multifunctional 2D vdW heterojunction devices and develops more possibilities to broaden their functionalities and applications.

Highly Efficient Room‐Temperature Phosphorescence Promoted via Intramolecular‐Space Heavy‐Atom Effect

AbstractPurely organic room‐temperature phosphorescence (RTP) materials have attracted increasing attention due to their unique photophysical properties and widespread optoelectrical applications, but the pursuit of high quantum yield is still a continual struggle for RTP emission under ambient conditions. Here, a series of novel RTP molecules (26CIM, 246CIM, 24CIM, and 25CIM) are developed on the basis of indole luminophore, in which a carbonyl group bridges indole and chloro‐substituted phenyl group. The structural isomerism is systematically regulated toward enhancing the intramolecular‐space heavy‐atom effect, thus promoting the spin–orbit coupling and intersystem crossing for high RTP efficiency. While rationally modulating the intramolecular‐space heavy‐atom effect, the phosphorescence efficiency is dramatically increased by 16‐fold from 2.9% (24CIM) to 48.9% (26CIM). Basically, the fully occupied chlorine atoms at the positions 2 and 6 can effectively favor the stronger intramolecular H…Cl effect, and the tight lock coupling with anti‐parallel stacking in 26CIM further boosts RTP emission synergistically. The experimental findings along with deeper theoretical insights elucidate the structure–performance relationship clearly, and further suggest a general strategy for rationally constructing high‐efficiency RTP materials.