Two-Coordinate Thermally Activated Delayed Fluorescence Coinage Metal Complexes: Molecular Design, Photophysical Characters, and Device Application.

Since the emergence of the first green light emission from a fluorescent thin-film organic light emitting diode (OLED) in the mid-1980s, a global consumer market for OLED displays has flourished over the past few decades. This growth can primarily be attributed to the development of noble metal phosphorescent emitters that facilitated remarkable gains in electrical conversion efficiency, a broadened color gamut, and vibrant image quality for OLED displays. Despite these achievements, the limited abundance of noble metals in the Earth's crust has spurred ongoing efforts to discover cost-effective electroluminescent materials. One particularly promising avenue is the exploration of thermally activated delayed fluorescence (TADF), a mechanism with the potential to fully harness excitons in OLEDs. Recently, investigations have unveiled TADF in a series of two-coordinate coinage metal (Cu, Ag, and Au) complexes. These organometallic TADF materials exhibit distinctive behavior in comparison to their organic counterparts. They offer benefits such as tunable emissive colors, short TADF emission lifetimes, high luminescent quantum yields, and reasonable stability. Impressively, both vacuum-deposited and solution-processed OLEDs incorporating these materials have achieved outstanding performance. This review encompasses various facets on two-coordinate TADF coinage metal complexes, including molecular design, photophysical characterizations, elucidation of structure-property relationships, and OLED applications.

Simultaneous Thermally Stimulated Delayed Phosphorescence (TSDP) and Thermally Activated Delayed Fluorescence (TADF) in a Two-Coordinated Au(I) Bimetallic Complex Featuring a Tandem Carbene Structure.

A bimetallic, two-coordinated carbene-metal-amine (cMa) Au(I) complex featuring a twisted tandem carbene structure (NHC1-Au-NHC2-Au-carbazolyl) was synthesized. The molecular structure in single crystals revealed a large dihedral angle between the two carbene ligands, while the bridged carbene NHC2 and carbazolyl (Cz) ligands were coplanar. A bluish green thermally stimulated delayed phosphorescence (TSDP) was observed in crystals with an emission lifetime over 70 µs, which can be attributed to the spin allowed diabatic population of a high-lying emissive triplet state from the 3LE characterized low-lying ones. The small rotation energy barrier of Cz along the coordination bond allowed conformers with large dihedral angles between NHC2 and Cz. The ICT characterized S1 state was consequently stabilized to achieve a thermally accessible energy gap to facilitate ISC between triplets and the S1, leading to the thermally activated delayed fluorescence (TADF). Simultaneous TSDP and TADF dual emission can be recorded in its doped polymer film owing to the coexistence of these different conformers.

Boundary-Rich Carbon-Based Electrocatalysts with Manganese(II)-Coordinated Active Environment for Selective Synthesis of Hydrogen Peroxide.

Coordinated manganese (Mn) electrocatalysts owing to their electronic structure flexibility, non-toxic and earth abundant features are promising for electrocatalytic reactions. However, achieving selective hydrogen peroxide (H2 O2 ) production through two electron oxygen reduction (2e-ORR) is a challenge on Mn-centered catalysts. Targeting this goal, we report on the creation of a secondary Mn(II)-coordinated active environment with reactant enrichment effect on boundary-rich porous carbon-based electrocatalysts, which facilitates the selective and rapid synthesis of H2 O2 through 2e-ORR. The catalysts exhibit nearly 100 % Faradaic efficiency and H2 O2 productivity up to 15.1 mol gcat -1 h-1 at 0.1 V versus reversible hydrogen electrode, representing the record high activity for Mn-based electrocatalyst in H2 O2 electrosynthesis. Mechanistic studies reveal that the epoxide and hydroxyl groups surrounding Mn(II) centers improve spin state by modifying electronic properties and charge transfer, thus tailoring the adsorption strength of *OOH intermediate. Multiscale simulations reveal that the high-curvature boundaries facilitate oxygen (O2 ) adsorption and result in local O2 enrichment due to the enhanced interaction between carbon surface and O2 . These merits together ensure the efficient formation of H2 O2 with high local concentration, which can directly boost the tandem reaction of hydrolysis of benzonitrile to benzamide with nearly 100 % conversion rate and exclusive benzamide selectivity.

Cytotoxic steroidal saponins from the rhizomes of Paris fargesii var. Petiolata.

Phytochemical investigation on the rhizomes of Paris fargesii var. petiolata (Baker ex C. H. Wright) Wang et Tang led to the isolation of five previously undescribed steroidal saponins, parpetiosides A-E (1-5), and six known analogs (6-11). Their structures were established by extensive spectroscopic data analysis and chemical methods. Compound 5 was a rare steroidal saponin with disaccharide moiety linked at C-26 of dehydrokryptogenin that was hardly seen in the genus Paris. The cytotoxicities of the isolated compounds against three human cancer cell lines (U87, HepG2 and SGC-7901) were evaluated, and compound 1 displayed certain inhibitory effect with IC50 values of 8.02 ± 0.45, 8.24 ± 0.57 and 6.20 ± 0.79 µM, respectively. Moreover, the preliminary mechanism of 1 inhibiting the proliferation of the three cancer cell lines might be related to cell cycle distribution and the induction of S phase arrest.

Cytotoxic Steroidal Saponins Containing a Rare Fructosyl from the Rhizomes of Paris polyphylla var. latifolia.

A phytochemical investigation of the steroidal saponins from the rhizomes of Paris polyohylla var. latifolia led to the discovery and characterization of three new spirostanol saponins, papolatiosides A-C (1-3), and nine known compounds (4-12). Their structures were established via extensive spectroscopic data analysis and chemical methods. Interestingly, compounds 1 and 2 possessed a fructosyl in their oligosaccharide moiety, which is rare in natural product and was firstly reported in family Melanthiaceae. The cytotoxicity of these saponins against several human cancer cell lines was evaluated by a CCK-8 experiment. As a result, compound 1 exhibited a significant cytotoxic effect on LN229, U251, Capan-2, HeLa, and HepG2 cancer cells with IC50 values of 4.18 ± 0.31, 3.85 ± 0.44, 3.26 ± 0.34, 3.30 ± 0.38 and 4.32 ± 0.51 µM, respectively. In addition, the result of flow cytometry analysis indicated that compound 1 could induce apoptosis of glioma cells LN229. The underlying mechanism was explored by network pharmacology and western bolt experiments, which indicated that compound 1 could induce glioma cells LN229 apoptosis by regulating the EGFR/PI3K/Akt/mTOR pathway.

A Configurationally Confined Thermally Activated Delayed Fluorescent Two-Coordinate CuI Complex for Efficient Blue Electroluminescence.

Thermally activated delayed fluorescence (TADF) from linear two-coordinate coinage metal complexes is sensitive to the geometric arrangement of the ligands. Herein we realize the tuning of configuration from coplanar to orthogonal gradually by variation of substituents. In a complex with confined twist configuration, its blue emission peaking at 458 nm presents a high ΦPL of 0.74 and a short τTADF of 1.9 µs, which indicates a fast enough kr,TADF of 3.9×105  s-1 and a depressed knr of 1.4×105  s-1 . Such outstanding luminescent properties are attributed to the proper overlap of HOMO and LUMO on CuI d orbitals that guarantees not only small ΔEST but also sufficient transition oscillator strength for fast k r , S 1 ${{k}_{{\rm r},{{\rm S}}_{1}}}$ . Vacuum-deposited blue OLEDs with either doped or host-free emissive layer present external quantum efficiencies over 20 % and 10 %, respectively, demonstrating the practicality of the configurationally confined strategy for efficient linear CuI TADF emitters.

A Luminescent Two-Coordinate AuI Bimetallic Complex with a Tandem-Carbene Structure: A Molecular Design for the Enhancement of TADF Radiative Decay Rate.

A luminescent bimetallic AuI complex comprised of N-heterocyclic carbene (NHC) and carbazole (Cz) ligands, that is, (NHC')Au(NHC)AuCz has been synthesized and studied. Both carbene ligands in the bimetallic complex act as electron acceptors in tandem to increase the energy separation between the ground and excited state, which is higher than those found in either monometallic analogue, (NHC)AuCz and (NHC')AuCz. A coplanar geometry designed into the tandem complex ensures sufficient electronic coupling between the π-orbitals of the ligands to impart a strong oscillator strength to the singlet intra-ligand charge-transfer (1 ICT) transition. Theoretical modelling indicates that the emissive ICT excited state involves both NHC ligands. The tandem complex gives blue luminescence (λmax =480 nm) with a high photoluminescent quantum yield (ΦPL =0.80) with a short decay lifetime (τ=0.52 µs). Temperature-dependent photophysical studies indicate that emission is via thermally assisted delayed fluorescence (TADF) and give a small singlet-triplet energy difference (ΔEST =50 meV, 400 cm-1 ) consistent with the short TADF lifetime.

Enhancement of the Luminescent Efficiency in Carbene-Au(I)-Aryl Complexes by the Restriction of Renner-Teller Distortion and Bond Rotation.

A series of (carbene)Au(I)(aryl) complexes are reported. The nature of the lowest excited state in these complexes changes character from metal-to-ligand charge transfer (MLCT) to interligand charge transfer (ICT) with increasing electron-donating strength of the aryl ligand. Complexes that have the MLCT lowest excited state undergo a Renner-Teller bending distortion upon excitation. Such a distortion leads to a large rate of nonradiative decay, on the order of 108 s-1. Renner-Teller-based nonradiative decay does not occur in chromophores with an ICT emissive state. Introducing a julolidine moiety and ortho-methyl substituents to the aryl group makes the molecule rigid and hinders the rotation along the Au-Caryl-coordinate bond. Consequently, the nonradiative decay rates of these ICT emitters are decreased and become lower than the radiative decay rate constants (kr = 105 s-1). Thus, high-luminescent efficiencies (ΦPL = 0.61 and 0.77) along with short lifetimes (τ < 2 µs) are obtained for yellow and green emitters, respectively. Thermally assisted delayed fluorescence behavior is observed, owing to the small exchange energy (ΔEST < 1600 cm-1) in these emitters.

[Experience of Professor Fan Yongsheng in treating arthralgia with insect drugs].

National-level famous traditional Chinese medicine( TCM) doctor Professor Fan Yong-sheng has high-level accomplishments in the treatment of arthralgia. According to clinical diagnosis and dialectic,TCM with appropriate medicinal properties were flexibly applied,with a remarkable efficacy. Especially in the application of insect drugs,he has accumulated abundant clinical experience.According to the main syndromes of arthralgia and pathogenic site,patient' s constitution,Scorpio,Scolopendra,Pheretima,Vespae Nidus,Bombyx Batryticatus,Manis Squama,Bungarus Parvus,Zaocys,Agkistrodon,Cicadae Periostracum,Aspongopus,Eupolyphaga Steleophaga,Silkworm Sand were properly selected. Attention was also paid to the compatibility between insect drugs and antirheumatic drugs,blood-activating drugs and tonifying drugs. In the premise of safe and effective application in the treatment of arthralgia,insect drugs show such efficacies as antipyretic,activating collaterals and relieving pain.

Alterations of Hippocampal Myelin Sheath and Axon Sprouting by Status Convulsion and Regulating Lingo-1 Expression with RNA Interference in Immature and Adult Rats.

Seizure-induced brain damage is age-dependent, as evidenced by the different alterations of neural physiopathology in developing and mature brains. However, little is known about the age-dependent characteristics of myelinated fiber injury induced by seizures. Considering the critical functions of oligodendrocyte progenitor cells (OPCs) in myelination and Lingo-1 signaling in regulating OPCs' differentiation, the present study aimed to explore the effects of Lingo-1 on myelin and axon in immature and adult rats after status convulsion (SC) induced by lithium-pilocarpine, and the differences between immature and adult brains. Dynamic variations in electrophysiological activity and spontaneous recurrent seizures were recorded by electroencephalogram monitoring after SC. The impaired microstructures of myelin sheaths and decrease in myelin basic protein caused by SC were observed through transmission electron microscopy and western blot analysis respectively, which became more severe in adult rats, but improved gradually in immature rats. Aberrant axon sprouting occurred in adult rats, which was more prominent than in immature rats, as shown by a Timm stain. This damage was improved or negatively affected after down or upregulating Lingo-1 expression. These results demonstrated that in both immature and adult brains, Lingo-1 signaling plays important roles in seizure-induced damage to myelin sheaths and axon growth. The plasticity of the developing brain may provide a potential window of opportunity to prevent the brain from damage.

Small Molecule Near-Infrared Boron Dipyrromethene Donors for Organic Tandem Solar Cells.

Three furan fused boron dipyrromethenes (BODIPYs) with a CF3 group on the meso-carbon are synthesized as near-infrared absorbing materials for vacuum processable organic solar cells. The best single junction device reaches a short-circuit current (jsc) of 13.3 mA cm-2 and a power conversion efficiency (PCE) of 6.1%. These values are highly promising for an electron donor material with an absorption onset beyond 900 nm. In a tandem solar cell comprising a NIR BODIPY subcell and a matching "green" absorber subcell, complementary absorption is achieved, resulting in PCE of ∼10%.

N-Heterocyclic carbenes: versatile second cyclometalated ligands for neutral iridium(III) heteroleptic complexes.

With 2-(2,4-difluorophenyl)pyridine (dfppy) as the first cyclometalated ligand and different monoanionic N-heterocyclic carbenes (NHCs) as the second cyclometalated ligands, 16 blue or greenish-blue neutral iridium(III) phosphorescent complexes, (dfppy)2Ir(NHC), were synthesized efficiently. The obtained Ir(III) complexes display typical phosphorescence of 455-485 nm with quantum yields up to 0.73. By modifying the phenyl moiety in the NHCs with electron-withdrawing substituents (e.g., -F or -CF3) or replacing it with N-heteroaromatic rings (pyridine or pyrimidine), the HOMO-LUMO gaps are broadened, and the emissions shift to the more blue region accordingly. Furthermore, to extend the application scope of NHCs as the second cyclometalated ligands, five other Ir(III) complexes from blue to red were synthesized with different first cyclometalated ligands. Finally, the organic light-emitting diodes using one blue emitter exhibit a maximum current efficiency of 37.83 cd A(-1), an external quantum efficiency of 10.3%, and a maximum luminance of 8709 cd m(-2). Our results demonstrate that NHCs as the second cyclometalated ligands are good candidates for the achievement of efficient phosphorescent Ir(III) complexes and corresponding devices.

Syntheses, photoluminescence, and electroluminescence of a series of iridium complexes with trifluoromethyl-substituted 2-phenylpyridine as the main ligands and tetraphenylimidodiphosphinate as the ancillary ligand.

Five bis-cyclometalated iridium complexes with tifluoromethyl-substituted 2-phenylpyridine (ppy) at different positions of its phenyl group as the main ligands and tetraphenylimidodiphosphinate (tpip) as the ancillary ligand, 2-6 (1 is a trifluoromethyl-free complex), were prepared, and their X-ray crystallography, photoluminescence, and electrochemistry were investigated. The number and positions of trifluoromethyl groups at the phenyl ring of ppy greatly affected the emission spectra of Ir(3+) complexes, and their corresponding emission peaks at 533, 502, 524, 480, and 542 nm were observed at room temperature, respectively. Constructed with complexes 2-6 as the emitters, respectively, the organic light-emitting diodes (OLEDs) with the structure of indium-tin oxide/1,1-bis[4-(di-p-tolylamino)phenyl]cyclohexane (30 nm)/Ir (x wt %):bis[3,5-bis(9H-carbazol-9-yl)phenyl]diphenylsilane (15 nm)/1,3,5-tris(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (45 nm)/LiF (1 nm)/Al (100 nm) showed good performances. Particularly, device G4 based on 4-trifluoromethyl-substituted complex 4 with x = 8 wt % obtained a maximum luminance of over 39000 cd m(-2) and maximum luminance efficiency (η(L)) and power efficiency (η(p)) of 50.8 cd A(-1) and 29.0 lm W(-1), respectively. The results suggested that all of the complexes 2-6 would have potential applications in OLEDs.

[Effect of yangyin yiqi huoxue recipe on immune balance of Th1/Th2 in serum and submaxillary glands of NOD mice with Sjogren's syndrome].

OBJECTIVE: To observe the effect of Yangyin Yiqi Huoxue Recipe (YYHR) on expression of interferon-gamma (IFN-gamma), IL-2, IL-4, IL-10, and immune balance of Th1/Th2 in serum and submaxillary glands of non-obese diabetic (NOD) mice with Sjogren's syndrome (SS), and to explore its mechanisms. METHODS: Totally 32 NOD mice were randomly into 4 groups, i.e., the model group, the Chinese medicine group [CM, administered with YYHR at the dose of 0.4 mL by gavage (100 g/kg)], the Western medicine group [WM group, administered with hydroxychloroquine 0.4 mL by gavage (60 mg/kg)], and the combined group [administered with YYHR (50 g/kg) and hydroxychloroquine (60 mg/kg) 0.4 mL by gavage], 8 mice in each group. Eight Balb/C mice were recruited as the normal control group. Mice were sacrificed to withdraw blood after 8 weeks. The submaxillary gland was excised. Serum levels of IFN-gamma, IL-2, IL-4, and IL-10 were detected by ELISA. Protein expression of IFN-gamma, IL-2, IL-4, and IL-10 in submaxillary glands was detected by SP method. RESULTS: Compared with the normal group, levels of IFN-gamma, IL-2, IL-4, and IL-10 in serum and submaxillary glands all increased in the model group (P < 0.05). Levels of IFN-gamma and IL-10 in serum in the CM group and the combined group were lower than those of the WM group (P < 0.05). Serum levels of IFN-gamma and IL-2 in submaxillary glands in combined group were lower than those of the WM group (P < 0.05). The ratio of IFN-gamma/IL-4 in serum and submaxillary glands in the model group were higher than that of the rest groups (P < 0.05). Besides, it was the nearest to that of the normal group. CONCLUSIONS: YYHR could decrease the levels of Th1 and Th2 related cytokines and the ratio of IFN-gamma/IL-4 in serum and submaxillary glands of NOD mice with SS. It could achieve therapeutic effects through adjusting immune balance of Th1/Th2 in SS mice.

[Effect of prescriptions replenishing vital essence, tonifying Qi and activating blood on TNF-alpha, IL-1beta expressions in serum and submaxillary gland of NOD mice with Sjogren's syndrome].

OBJECTIVE: To observe effect of prescriptions replenishing vital essence, tonifying Qi and activating blood on expression of tumor necrosis factor-alpha (TNF-alpha) and interleukin-IP (IL-1beta) in serum and submaxillary gland of non-obese diabetic (NOD) mice with Sjogren's syndrome. METHOD: Thirty-two NOD mice were divided into four groups at random: the model group, the traditional Chinese medicine (TCM) group, the hydroxychloroquine group, the TCM and western medicine (WM) group, with 8 mice in each group. Eight Balb/C mice were taken as the normal normal control group. The TCM group was orally administered with 0.4 mL decoction replenishing vital essence, tonifying Qi and activating blood (100 g x kg(-1)) everyday; the hydroxychloroquine group were given 0.4 mL hydroxychloroquine (60 mg x kg(-1)) everyday; the TCM WM group were given 0.4 mL decoction, replenishing vital essence tonifying Qi and activating blood (50 g x kg(-1)) and hydroxychloroquine (60 mg x kg(-1)) everyday. Mice were sacrificed after eight weeks, and their arterial blood and tissues of submaxillary gland were collected. The levels of TNF-alpha, IL-1beta in serum were detected by ELISA. Expressions of TNF-alpha, IL-1beta protein in submaxillary gland were detected by immunohisto-chemistry. RESULT: Compared with other groups, TNF-alpha, IL-1beta in serum and submaxillary gland in the model group were higher (P < 0.05). The normal group showed lower serum TNF-alpha level than other groups (P < 0.05), but without statistical significance compared with the TCM group. IL-1beta in serum in the TCM group and the TCM WM group were lower than that of the hydroxychloroquine group (P < 0.05), but without statistical significance compared with the normal group. TNF-alpha protein expression in the TCM group and the TCM WM group showed no significant difference compared with the normal group, whereas the TCM WM group were notably lower than that of the hydroxychloroquine group (P < 0.05). IL-1beta expression in the TCM WM group showed no significant difference compared with the normal group. CONCLUSION: The decoction replenishing vital essence, tonifying Qi and activating blood can decrease the levels of TNF-alpha, IL-1beta in serum and submaxillary gland of NOD mice with Sjogren's syndrome. It may improve pathological damage of submaxillary gland by regulating Th1/Th2 cell factors, in order to achieve the therapeutic effect on SS.

[Effect of nourishing Yin, strengthening Qi and activating blood decoction on Fas/FasL in salivary glands of NOD mice with Sjogren's syndrome and their mRNA expression].

OBJECTIVE: To observe the effect of nourishing Yin, strengthening Qi and activating blood decoction on Fas/FasL in salivary glands of NOD mice with Sjogren's syndrome and their mRNA expression. METHOD: Thirty-two NOD mice were randomly divided into the model group, the traditional Chinese medicine group (TCM group, orally given 0.4 mL nourishing Yin, strengthening Qi and activating blood decoction as per 100 g x kg(-1) everyday), the hydroxychloroquine group (given 0.4 mL hydroxychloroquine as per 60 mg x kg(-1) everyday), the traditional Chinese medicine and western medicine group (TCM WM group, given nourishing Yin, Strengthening Qi and activating blood decoction 50 g x kg(-1) and hydroxychloroquine 60 mg x kg(-1), 0.4 mL everyday), with eight mice in each group. Eight Balb/C mice were selected as the normal control group (normal group). All of mice were killed after eight weeks, and their submaxillary glands were dissected. The expression levels of Fas/FasL were examined by immunohistochemical method, and the FasL mRNA was detected by RT-PCR. RESULT: The expression levels of Fas/FasL in salivary glands of the model group were higher than that of other groups (P < 0.05). The expression level of FasL of the normal group was much lower than that in the hydroxychloroquine group (P < 0.05). The relative expression level of Fas mRNA in salivary glands of the model group was higher than that in other groups, but the control group was notably lower than other groups (P < 0.05). The expression level of FasL mRNA in salivary glands of the model group was higher than that in TCM and TCM WM groups (P < 0.05). But the expression level in TCM WM group was notably lower than the hydroxychloroquine group (P < 0.05). CONCLUSION: The nourishing Yin, strengthening Qi and activating blood decoction could down-regulate the expression level of Fas/FasL in salivary glands of NOD mice with Sjogren's syndrome and their mRNA expression, and had a better efficacy after being combined with hydroxychloroquine. The nourishing Yin, strengthening Qi and activating blood decoction might treat the Sjogren's Syndrome by reducing apoptosis which is regulated by Fas/FasL

The alkaloids with neuroprotective effect from the root bark of Ailanthus altissima.

The chemical constituent investigation on the root bark of Ailanthus altissima leads to the isolation of a new ß-carboline alkaloid, 14(S),15-dihydroxy-6-methoxy-ß-carboline (1), along with nine known alkaloids. The structure of new compound was elucidated on basis of extensive spectroscopic analysis, especially two-dimensional (2D) NMR techniques and the absolute configuration of C-14 was determined by ECD calculation. The neuroprotective effect of the isolated compounds on PC12 cells against the serum deprivation injury was evaluated by MTT method. As a result, compound 7 revealed protective effect on PC12 cells and the cell survival rate was significantly increased.

New steroidal saponins from the roots of Paris verticillata.

Four new polyhydroxylated steroidal saponins, parisverticillatosides A-D (1-4), together with four known spirostanol saponins (5-8) were isolated from the roots of Paris verticillata. Their structures were elucidated on the basis of extensive spectroscopic analysis and chemical evidences. The discovery of the new compounds 1-4 extended the diversity and complexity of this spirostanol saponin family. The saponins 5 and 6 exhibited cytotoxicities against two human glioma cell lines.

Photomultiplication-Type Organic Photodetectors for Near-Infrared Sensing with High and Bias-Independent Specific Detectivity.

Highly responsive organic photodetectors allow a plethora of applications in fields like imaging, health, security monitoring, etc. Photomultiplication-type organic photodetectors (PM-OPDs) are a desirable option due to their internal amplification mechanism. However, for such devices, significant gain and low dark currents are often mutually excluded since large operation voltages often induce high shot noise. Here, a fully vacuum-processed PM-OPD is demonstrated using trap-assisted electron injection in BDP-OMe:C60 material system. By applying only -1 V, compared with the self-powered working condition, the responsivity is increased by one order of magnitude, resulting in an outstanding specific detectivity of ≈1013  Jones. Remarkably, the superior detectivity in the near-infrared region is stable and almost voltage-independent up to -10 V. Compared with two photovoltaic-type photodetectors, these PM-OPDs exhibit the great potential to be easily integrated with state-of-the-art readout electronics in terms of their high responsivity, fast response speed, and bias-independent specific detectivity. The employed vacuum fabrication process and the easy-to-adapt PM-OPD concept enable seamless upscaling of production, paving the way to a commercially relevant photodetector technology.

Design and optimization of two-degree-of-freedom parallel four pure-slide- and four parallel quadrilateral-pair precision positioning platform.

Aiming at the complex structure, small output displacement, and low positioning accuracy of the two-degree-of-freedom (2-DOF) precision positioning platform, theoretical analyses and experimental tests are carried out so that the platform has the characteristics of compact structure, large output stroke, and high positioning accuracy. First, to optimize the structural parameters of the positioning platform, a modeling method to improve the modeling accuracy of the compliant mechanism of the positioning platform is proposed. A static model of the positioning platform based on Euler-Bernoulli beam theory and the sixth-order compliance matrix method is established, and the accuracy of the model is verified by simulation. In addition, the single-objective genetic optimization algorithm is used to optimize the structural size parameters of the positioning platform, and the optimal solution set of the structural size parameters of the positioning platform is obtained by taking the displacement amplification rate of the positioning platform as the optimization target. Finally, according to theoretical and simulation analysis and optimization results, an experimental prototype was fabricated, and a series of experimental tests were carried out on the working stroke, displacement magnification, and output stiffness. The experimental results show that the displacement magnification of the positioning platform reaches 3.39, the positioning stroke is 89.2 × 85.9 µm2, and the displacement resolutions of the x-axis and y-axis are 35 and 31 nm, respectively. The positioning platform designed in this paper meets the requirements of large output stroke and high positioning accuracy.