High-Performance n-Type Polymeric Mixed Ionic-Electronic Conductors: The Impacts of Halogen Functionalization.

Developing high-performance n-type polymer mixed ionic-electronic conductors (PMIECs) is a grand challenge, which largely determines their applications in vaious organic electronic devices, such as organic electrochemical transistors (OECTs) and organic thermoelectrics (OTEs). Herein, two halogen-functionalized PMIECs f-BTI2g-TVTF and f-BTI2g-TVTCl built from fused bithiophene imide dimer (f-BTI2) as the acceptor unit and halogenated thienylene-vinylene-thienylene (TVT) as the donor co-unit are reported. Compared to the control polymer f-BTI2g-TVT, the fluorinated f-BTI2g-TVTF shows lower-positioned lowest unoccupied molecular orbital (LUMO), improved charge transport property, and greater ion uptake capacity. Consequently, f-BTI2g-TVTF delivers a state-of-the-art µC* of 90.2 F cm-1 V-1 s-1 with a remarkable electron mobility of 0.41 cm2 V-1 s-1 in OECTs and an excellent power factor of 64.2 µW m-1 K-2 in OTEs. An OECT-based inverter amplifier is further demonstrated with voltage gain up to 148 V V-1 , which is among the highest values for OECT inverters. Such results shed light on the impacts of halogen atoms on developing high-performing n-type PMIECs.

High-performance n-type organic thermoelectrics enabled by modulating cyano-functionalized polythiophene backbones.

The scarcity of n-type polymers with high electrical conductivity (σ) and power factor (PF) is the major challenge for organic thermoelectrics (OTEs). By integrating cyano functionalities and an intramolecular conformation lock, we herein synthesize a new electron-deficient building block, CNg4T2, bearing long 1,4,7,10-tetraoxahendecyl side chains, and then further develop two n-type polythiophene derivatives, CNg4T2-2FT and CNg4T2-CNT2, with 3,4-difluorothiophene and 3,3'-dicyano-2,2'-bithiophene as co-units, respectively. Compared with CNg4T2-2FT, CNg4T2-CNT2 features a deeper-positioned lowest unoccupied molecular orbital (LUMO) while maintaining a high degree of backbone coplanarity. As a consequence, the CNg4T2-CNT2 film with molecular dopant N-DMBI delivered an impressive σ of 13.2 S cm-1 and a high PF of up to 10.84 µW m-1 K-2, significantly outperforming CNg4T2-2FT and benchmark n-type polymer N2200 films. To the best of our knowledge, this PF of CNg4T2-CNT2 devices is the highest value for n-type polythiophenes in OTEs. Further characterizations indicate that the high performance of CNg4T2-CNT2-based devices is attributed to the high doping efficiency and ordered packing of polymer chains. Our study demonstrates that CNg4T2 is a highly appealing electron-deficient building block for n-type OTE polymers and also suggests that fine-tuning of the polymer backbone is a powerful approach to accessing high-performance n-type polymers for OTE devices.

Biselenophene Imide: Enabling Polymer Acceptor with High Electron Mobility for High-Performance All-Polymer Solar Cells.

The shortage of narrow band gap polymer acceptors with high electron mobility is the major bottleneck for developing efficient all-polymer solar cells (all-PSCs). Herein, we synthesize a distannylated electron-deficient biselenophene imide monomer (BSeI-Tin) with high purity/reactivity, affording an excellent chance to access acceptor-acceptor (A-A) type polymer acceptors. Copolymerizing BSeI-Tin with dibrominated monomer Y5-Br, the resulting A-A polymer PY5-BSeI shows a higher molecular weight, narrower band gap, deeper-lying frontier molecular orbital levels and larger electron mobility than the donor-acceptor type counterpart PY5-BSe. Consequently, the PY5-BSeI-based all-PSCs deliver a remarkable efficiency of 17.77 % with a high short-circuit current of 24.93 mA cm-2 and fill factor of 75.83 %. This efficiency is much higher than that (10.70 %) of the PY5-BSe-based devices. Our study demonstrates that BSeI is a promising building block for constructing high-performance polymer acceptors and stannylation of electron-deficient building blocks offers an excellent approach to developing A-A type polymers for all-PSCs and even beyond.

Target Therapy for Buried Interface Enables Stable Perovskite Solar Cells with 25.05% Efficiency.

The buried interface in perovskite solar cells (PSCs) is pivotal for achieving high efficiency and stability. However, it is challenging to study and optimize the buried interface due to its non-exposed feature. Here, a facile and effective strategy is developed to modify the SnO2 /perovskite buried interface by passivating the buried defects in perovskite and modulating carrier dynamics via incorporating formamidine oxalate (FOA) in SnO2 nanoparticles. Both formamidinium and oxalate ions show a longitudinal gradient distribution in the SnO2 layer, mainly accumulating at the SnO2 /perovskite buried interface, which enables high-quality upper perovskite films, minimized defects, superior interface contacts, and matched energy levels between perovskite and SnO2 . Significantly, FOA can simultaneously reduce the oxygen vacancies and tin interstitial defects on the SnO2 surface and the FA+ /Pb2+ associated defects at the perovskite buried interface. Consequently, the FOA treatment significantly improves the efficiency of the PSCs from 22.40% to 25.05% and their storage- and photo-stability. This method provides an effective target therapy of buried interface in PSCs to achieve very high efficiency and stability.

Cyano-Functionalized Fused Bithiophene Imide Dimer-Based n-Type Polymers for High-Performance Organic Thermoelectrics.

Doped n-type polymers usually exhibit low electrical conductivities and thermoelectric power factors (PFs), restricting the development of high-performance p-n-junction-based organic thermoelectrics (OTEs). Herein, the design and synthesis of a new cyano-functionalized fused bithiophene imide dimer (f-BTI2), CNI2, is reported, which synergistically combines the advantages of both cyano and imide functionalities, thus leading to substantially higher electron deficiency than the parent f-BTI2. On the basis of this novel building block, a series of n-type donor-acceptor and acceptor-acceptor polymers are successfully synthesized, all of which show good solubility, deep-lying frontier molecular orbital levels, and favorable polymer chain orientation. Among them, the acceptor-acceptor polymer PCNI2-BTI delivers an excellent electrical conductivity up to 150.2 S cm-1 and a highest PF of 110.3 µW m-1  K-2 in n-type OTEs, attributed to the optimized polymer electronic properties and film morphology with improved molecular packing and higher crystallinity assisted by solution-shearing technology. The PF value is the record of n-type polymers for OTEs to date. This work demonstrates a facile approach to designing high-performance n-type polymers and fabricating high-quality films for OTE applications.

n-Type Polymer Semiconductors Based on Dithienylpyrazinediimide.

The development of n-type organic semiconductors critically relies on the design and synthesis of highly electron-deficient building blocks with good solubility and small steric hindrance. We report here a strongly electron-deficient dithienylpyrazinediimide (TPDI) and its n-type semiconducting polymers. The pyrazine substitution leads to the resulting polymers with much lower-lying lowest unoccupied molecular orbital (LUMO) levels and improved backbone planarity compared to the reported dithienylbenzodiimide (TBDI)- and fluorinated dithienylbenzodiimide (TFBDI)-based polymer analogues, thus yielding n-type transport character with an electron mobility up to 0.44 cm2 V-1 s-1 in organic thin-film transistors. These results demonstrate that dithienylpyrazinediimide is a highly promising electron-deficient building block for constructing high-performance n-type polymers and the incorporation of pyrazine into imide-functionalized (hetero)arenes is an effective strategy to develop n-type polymers with deep-lying frontier molecular orbital (FMO) levels for organic optoelectronic devices.

Interfacial Passivation Engineering for Highly Efficient Perovskite Solar Cells with a Fill Factor over 83.

Charge carrier nonradiative recombination (NRR) caused by interface defects and nonoptimal energy level alignment is the primary factor restricting the performance improvement of perovskite solar cells (PSCs). Interfacial modification is a vital strategy to restrain NRR and enable high-performance PSCs. We report here two interfacial materials, PhI-TPA and BTZI-TPA, consisting of phthalimide and a 2,1,3-benzothiadiazole-5,6-dicarboxylicimide core, respectively. The difunctionalized BTZI-TPA with imide and thiadiazole shows higher hole mobility, better aligned energy levels, and stronger interaction with uncoordinated Pb2+ on the perovskite surface, suppressing NRR and carrier accumulation at the interface of perovskite/spiro-OMeTAD and yielding enhanced open-circuit voltage and fill factor. Consequently, the PSC based on BTZI-TPA delivers a high efficiency of 24.06% with an excellent fill factor of 83.10%, superior to that (21.47%) of the reference cell without an interfacial layer, and 21.45% efficiency for the device with a scaled-up area (1.00 cm2). These results underscore the potential of imide and thiadiazole groups in developing interfacial layers with strong passivation capability, effective charge transport property, and fine-tuned energetics for stable and efficient PSCs.

Polymer Acceptors for High-Performance All-Polymer Solar Cells.

All-polymer solar cells (all-PSCs) have attracted considerable attention owing to their pronounced advantages of excellent mechanical flexibility/stretchability and greatly enhanced device stability as compared to other types of organic solar cells (OSCs). Thanks to the extensive research efforts dedicated to the development of polymer acceptors, all-PSCs have achieved remarkable improvement of photovoltaic performance, recently. This review summarizes the recent progress of polymer acceptors based on the key electron-deficient building blocks, which include bithiophene imide (BTI) derivatives, boron-nitrogen coordination bond (B←N)-incorporated (hetero)arenes, cyano-functionalized (hetero)arenes, and fused-ring electron acceptors (FREAs). In addition, single-component-based all-PSCs are also briefly discussed. The structure-property correlations of polymer acceptors are elaborated in detail. Finally, we offer our insights into the development of new electron-deficient building blocks with further optimized properties and the polymers built from them for efficient all-PSCs.

Fused Bithiophene Imide Dimer-Based n-Type Polymers for High-Performance Organic Electrochemical Transistors.

The development of n-type organic electrochemical transistors (OECTs) lags far behind their p-type counterparts. In order to address this dilemma, we report here two new fused bithiophene imide dimer (f-BTI2)-based n-type polymers with a branched methyl end-capped glycol side chain, which exhibit good solubility, low-lying LUMO energy levels, favorable polymer chain orientation, and efficient ion transport property, thus yielding a remarkable OECT electron mobility (µe ) of up to ≈10-2  cm2 V-1 s-1 and volumetric capacitance (C*) as high as 443 F cm-3 , simultaneously. As a result, the f-BTI2TEG-FT-based OECTs deliver a record-high maximum geometry-normalized transconductance of 4.60 S cm-1 and a maximum µC* product of 15.2 F cm-1 V-1 s-1 . The µC* figure of merit is more than one order of magnitude higher than that of the state-of-the-art n-type OECTs. The emergence of f-BTI2TEG-FT brings a new paradigm for developing high-performance n-type polymers for low-power OECT applications.

Aza-Based Donor-Acceptor Conjugated Polymer Nanoparticles for Near-Infrared Modulated Photothermal Conversion.

It is highly desired that synthesis of photothermal agents with near-infrared (NIR) absorption, excellent photostability, and high photothermal conversion efficiency are essential for potential applications. In this work, three (D-A) conjugated polymers (PBABDF-BDTT, PBABDF-BT, and PBABDF-TVT) based on aza-heterocycle, bis(2-oxo-7-azaindolin-3-ylidene)benzodifurandione (BABDF) as the strong acceptor, and benzodithiophene-thiophene (BDTT), bithiophene (BT), and thiophene-vinylene-thiophene (TVT) as the donors, were designed and synthesized. The conjugated polymers showed significant absorption in the NIR region and a maximum absorption peak at 808 nm by adjusting the donor and acceptor units. Their photothermal properties were also investigated by using poly(ethylene glycol)-block-poly(hexyl ethylene phosphate) (mPEG-b-PHEP) to stabilize the conjugated polymers. Photoexcited conjugated polymer (PBABDF-TVT) nanoparticles underwent non-radiative decay when subjected to single-wavelength NIR light irradiation, leading to an excellent photothermal conversion efficiency of 40.7%. This work indicated the aza-heterocycle BABDF can be a useful building block for constructing D-A conjugated polymer with high conversion efficiency.

Synthesis of a Water-Soluble Carboxylatobiphen[4]arene and Its Selective Complexation toward Acetylcholine.

The first water-soluble biphen[4]arene containing eight carboxylato moieties (carboxylatobiphen[4]arene, CBP4) has been synthesized. Selective molecular recognition of acetylcholine (ACh) against choline (Ch) and betaine (Bt) and pH-responsive host-guest complexation in aqueous media are described.

Molecular Recognition Properties of Biphen[4]arene.

Biphen[n]arenes (n=3, 4) are a new family of macrocyclic hosts. Here, we describe the molecular recognition behavior of hydroxylated biphen[4]arene (OHBP4) for the first time. A series of cationic guests with different sizes and shapes, including quaternary ammonium salts (1⋅PF6 and 2⋅PF6 ), pyridinium-based guests (3⋅2 PF6 -6⋅2 PF6 ), and cobaltocenium hexafluorophosphate (7⋅PF6 ), were chosen as model guest molecules. OHBP4 exhibits good selectivity towards the 2,7-dibutyldiazapyrenium bis(hexafluorophosphate) (4⋅2 PF6 ) axle to form a [2]pseudorotaxane-type complex. In contrast, hydroxylated biphen[3]arene (OHBP3) cannot bind with this big guest. In addition, OHBP4 strongly interacts with adamantane derivative 2⋅PF6 and cobaltocenium 7⋅PF6 , which have tridimensional shape and relatively large size. The association constant of the 7+ ⊂OHBP4 complex in 1:1 (v/v) [D6 ]acetone/CD2 Cl2 solution is up to 3100±300 m-1 .

Multifocal electroretinogram in non-pathological myopic subjects: correlation with optical coherence tomography.

AIM: To investigate the changes of retinal function in non-pathological myopic subjects using multifocal electroretinography (mfERG) and to correlate the data with the central macular thickness obtained using optical coherence tomography (OCT). METHODS: One hundred and thirteen subjects (113 eyes) with age range from 18 to 35y were enrolled in the study. The subjects were divided into four groups according to spherical equivalent (SE) and axial length (AL): emmetropia group (EG, n=31; SE: +0.75 to -0.50 D; AL: 22 to 24 mm), low and medium myopia group (LMMG, n=26; SE: >-0.50 to -6.00 D; AL: >24 to 26 mm), high myopia group (HMG, n=34; SE: >-6.00 to -10.00 D; AL: >26 to 28 mm) and super high myopia group (SHMG, n=22; SE: >-10.00 D; AL:>28 mm). The P1 amplitude density, P1 amplitude, and P1 implicit time of the first-order kernel mfERG responses were obtained and grouped into five rings. The central subfield macular thickness (CST) was obtained using macular cube 512×218 scan of Cirrus HD-OCT. RESULTS: With the increasing of eccentricity, the first positive peak (P1) amplitude density (P=0.0000, 0.0001, 0.0021 in ring 1-3 respectively) and P1 amplitude (all P=0.0000 in ring 1-5) of each group decreased. With the increasing of myopia, P1 implicit time gradually extended (all P=0.0000 in ring 1-3). The average CST in four diagnostic groups was 241.56±12.72 µm, 244.56±12.19 µm, 254.33±11.61 µm, 261.75±11.83 µm respectively. With the increasing of myopia, CST increased (P<0.001). There was negative relationship between CST and P1 amplitude, P1 amplitude density (r=-0.402, P<0.001; r=-0.261, P=0.003). There was positive relationship between CST and P1 implicit time (r=0.34, P<0.001). CONCLUSION: With the increasing of myopia, P1 amplitude density and P1 amplitude of the first-order reaction gradually reduced. This showed potential decline in retinal function in myopia. To some extent it may reflect the functional disorder or depression of the visual cells. The exact mechanism needs further study.

Molecular binding behavior of bipyridium derivatives by water-soluble carboxylato-biphen[3]arene.

Complexation of two types of dicationic bipyridium guests, paraquat derivatives and bis(N-mono-substituted bipyridine) cations, by a negatively charged carboxylato-biphen[3]arene (CBP3) in water is reported. CBP3 could strongly interact with these guests, where charge-transfer and electrostatic interactions play important roles.

Hypertension and health-related quality of life: an epidemiological study in patients attending hospital clinics in China.

OBJECTIVE: To examine the relationship between hypertension and health-related quality of life in patients attending hospital clinics in China. DESIGN AND METHODS: A cross-sectional survey. Patients over the age of 35 years attending outpatient clinics in 18 hospitals of eight major cities of northern and southern China were interviewed between June and July, 1999. Trained fieldworkers completed questionnaires regarding demographics, hypertension knowledge and awareness, treatment history and quality of life issues. Qualified physicians performed blood pressure assessments. RESULTS: A total of 9703 volunteers were enrolled; 4510 (46.5%) had hypertension. The results showed that hypertensive subjects scored lower in the multiple linear regression analyses in most questions on the quality of life questionnaire than those without hypertension after controlling for age, sex, sociodemographic factors, and co-morbidity. There was a strikingly high prevalence of physical complaints or symptoms. Among the variables considered, age, sex, hypertension, body mass index, educational level, smoking, history of cholesterol, family history of cardiovascular diseases and history of diabetes were statistically significantly correlated with health-related quality of life. Subjects aware of having high blood pressure had a lower health-related quality of life score than subjects with high blood pressure but unaware of the diagnosis. Among treated subjects, those with controlled hypertension had higher health-related quality of life scores than those with poorly controlled hypertension. CONCLUSIONS: Hypertensive individuals represent a vulnerable population that merits special attention from healthcare providers and systems. This is especially important given that low health-related quality of life can be a risk factor for subsequent cardiovascular events or complications.

Awareness, treatment and control of hypertension in patients attending hospital clinics in China.

OBJECTIVES: To determine awareness, treatment and control of hypertension in patients attending hospital clinics in China. DESIGN: A cross-sectional survey. PATIENTS AND SETTING: Patients over the age of 35 years, who were attending outpatient clinics in 18 hospitals of eight major cities of Northern and Southern China, were interviewed face-to-face between June and July 1999. METHODS: Trained fieldworkers completed questionnaires regarding demographics, hypertension knowledge and awareness, treatment history and quality of life issues. Qualified physicians performed blood pressure assessment. RESULTS: A total of 9703 volunteers enrolled, of which 4510 (46.5%) were hypertensives. Among hypertensives, 23% were unaware of their high blood pressure. Although 89% of those aware reported receiving therapy, only 56% of them were taking medication regularly, and 33% were thus controlled. Although 69% of all hypertensives measuring at examination reported taking antihypertensive therapy, only 44% of them were actually taking medication regularly. Furthermore, 73% of hypertensives believed hypertension was not a serious problem, and required no regular medication. CONCLUSIONS: The results showed that a substantial number of outpatients have a hypertensive range of blood pressure. Although most of these patients are already being treated with drug regimen, the patient's misconceptions and lack of knowledge about the disease appear to be the major cause of treatment failure. The low rate of high blood pressure control for both sexes calls for further improvements.