Wei Yang

Background: People living with chronic disease, particularly seniors (≥60 years old), made up of most severe symptom and death cases among SARS-CoV-2 infected patients. However, they are lagging behind in the national COVID-19 vaccination campaign in China due to the uncertainty of vaccine safety and effectiveness. Safety and immunogenicity data of COVID-19 vaccines in people with underlying medical conditions are needed to address the vaccine hesitation in this population. Methods: We included participants (≥40 years old) who received two doses of CoronaVac inactivated vaccines (at a 3–5 week interval) and were healthy or had at least one of 6 common chronic diseases. The incidence of adverse events after vaccination was monitored. Vaccine immunogenicity was studied by determining neutralizing antibodies and SARS-CoV-2-specific T cell responses post vaccination. Results: Here we show that chronic diseases are associated with a higher rate of mild fatigue following the first dose of CoronaVac. By day 14–28 post vaccination, the neutralizing antibody level shows no significant difference between disease groups and healthy controls, except for people with coronary artery disease (p = 0.0287) and chronic respiratory disease (p = 0.0416), who show moderate reductions. Such differences diminish by day 90 and 180. Most people show detectable SARS-CoV-2-specific T cell responses at day 90 and day 180 without significant differences between disease groups and healthy controls. Conclusions: Our results highlight the comparable safety, immunogenicity and cellular immunity memory of CoronaVac in seniors and people living with chronic diseases. This data should reduce vaccine hesitancy in this population.

Herein, a novel electron-deficient conjugated water/alcohol-soluble polyelectrolyte (WSPE) named PFSOPyCl-E, consisting of dibenzothiophene-S,S-dioxide, bispyridinium salts and fluorene with ethylene oxide side chains, was presented. Previously we have synthesized another WSPE (PFSOPyCl) composed of the same backbone as that of PFSOPyCl-E but with octyl side chains. PFSOPyCl and PFSOPyCl-E were applied as cathode buffer materials (CBMs) to inverted polymer solar cells (PSCs) of poly[4,8-bis(2-ethylhexyloxyl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-ethylhexyl-3-fluorothithieno[3,4-b]thiophene-2-carboxylate-4,6-diyl] (PTB7):[6,6]-phenyl-C₇₁ butyric acid methyl ester (PC₇₁BM) systems, and simultaneous enhancements in open-circuit voltage (V_oc), short-circuit current density (J_sc) and fill factor (FF) could be achieved when inserting these cathode buffer layers (CBLs). It was found that these CBLs could build directed dipoles at the indium tin oxide (ITO)/active layer interfaces, leading to the reductions in the ITO work function (WF) and improvements in V_oc for the modified devices. The J_sc and FFs of PSCs were increased by several mechanisms. Firstly, the energy level alignments between the reduced ITO WFs (4.30–4.32 eV), deep LUMO energy levels (E_LUMO) of these CBLs (4.04–4.10 eV) and E_LUMO of PC₇₁BM (∼3.90 eV) could generate good ohmic contacts, facilitating electron extractions and transportations. Secondly, these CBLs were able to n-dope PC₇₁BM at the interfaces, inducing efficient electron-transporting pathways in the devices. Moreover, these polar polymeric CBLs could improve the compatibilities between ITO and the active layers, thus decreasing the interfacial resistances. It is worth noting that PFSOPyCl-E showed better cathode-modifying performance than PFSOPyCl, probably since PFSOPyCl-E with ethylene oxide side chains of high polarity and flexibility possessed better wettability with ITO and smoother films than PFSOPyCl. Hence, the devices modified by PFSOPyCl-E displayed lower contact resistances and higher FFs and J_sc than the PFSOPyCl-modified ones. Therefore, this class of electron-deficient conjugated WSPEs are promising CBMs for high-performance PSCs.

A series of solution-processible blue small molecules based on bis(benzothiophene-S,S-dioxide) fused polycyclic aromatics (FBTO) are synthesized, which show the high EL performance with the maximum current efficiency of 6.37 cd A⁻¹.

Near-infrared polymer light-emitting diodes (NIR-PLEDs) possess great potential in applications ranging from night-vision devices to optical communications. Here, we obtained NIR emission from normal red fluorescent polymers using an inverted device structure with the aid of micro-cavity effects. By tuning the thickness of the emissive layer, the inverted NIR-PLED based on PPF-FSO15-DHTBT10 and MEH-PPV elicited NIR emission with the main peaks located at 700 nm and 706 nm, and maximum external quantum efficiency (EQE_max) of 0.54% and 1.03%, respectively. An increase in emissive-layer thickness caused relative variation of the recombination area, which led to wide control of electroluminescence (EL) spectra in the inverted device. These results revealed that tuning the EL spectrum using an inverted device structure could be a promising method to realize NIR emission.

Tandem polymer light emitting diodes (tandem PLEDs) consisting of two EL units, connected by a charge generation layer (CGL), exhibited the advantages of improved luminous efficiency and lifetime. Here, the ether-soluble PTPA-P and alcohol-soluble ZnO were used as the CGL for a tandem PLED with a configuration of ITO/ZnO/PEIE/P-PPV/PEDOT:PSS/PTPA-P/ZnO/PFN-OX/P-PPV/MoO₃/Al. The water wetting ability of the P-PPV layer was obviously improved by oxygen plasma treatment, which enabled PEDOT:PSS to be spin-coated on the surface directly. Appropriately choosing an orthogonal solvent and a cross-linked material ensured the successful fabrication of an eight-layered device by solution processing. The whole connecting layer of PEDOT:PSS/PTPA-P/ZnO/PFN-OX has a high optical transmittance, which ensures the extraction of the light generated in the tandem PLED. The PTPA-P/ZnO CGL has more effective charge generation ability than the PEDOT:PSS/ZnO CGL, due to the shallower HOMO level of PTPA-P and the larger contact area between PTPA-P and ZnO, compared with those based on PEDOT:PSS. Due to the higher charge generation ability of the PTPA-P/ZnO CGL the tandem device exhibited a high luminous efficiency of 26.9 cd A⁻¹ and an external quantum efficiency (EQE) of 10.4%, which were over 2 times those in the relevant single-emitting-layer device.

Hole-transporting polymers, PTPA-F, PTPA-Cz, PTPA-P, PTPA-T and PPT-T, were synthesized using triphenylamine or phenothiazine as the backbone unit, and oligo(ethylene glycol) (OEG) as the side chain, respectively. Thereinto, PTPA-F, PTPA-Cz and PTPA-P emit blue light and own wide bandgaps larger than 2.8 eV, while PTPA-T and PPT-T have narrower bandgaps of 2.56 eV and 2.35 eV, respectively. All of the polymers are soluble in ether solvents, such as dioxane and dioxolane, but insoluble in alcoholic solvents. Moreover, the resulting polymers have shallow highest occupied molecular orbital (HOMO) energy levels in the range of −5.12 to −4.87 eV, which can be adopted as electron donors to construct charge carrier generation layers (CGLs) (with zinc oxide (ZnO) as the electron acceptor) by the orthogonal solvent process. The PTPA-P/ZnO based CGL device exhibits the best charge carrier generation and transferability with the highest current density of over 600 mA cm⁻² at 8 V, which is on a par with the PEDOT:PSS/ZnO based device. The results reveal that these hole-transporting polymers have great potential to fabricate highly efficient CGLs for tandem organic light-emitting diodes (OLEDs).

Asymmetrical five ring fused compounds based on S,S-dioxide benzothiophene, 9,9-dioctylfluorene[2,3-b]benzo[d]thiophene-S,S-dioxide(BTOF) and N-(2-decyltetradecyl)carbazole[2,3-b]benzo[d]thiophene-S,S-dioxide (BTOCz) were synthesized and characterized. BTOF and BTOCz were readily soluble in common organic solvents and exhibited high thermal stability with the melting points (T_ms) of 119 °C and 150 °C, and thermal decomposition temperatures (T_ds) of 280 °C and 338 °C, respectively. The highest occupied molecular orbital energy levels (HOMOs), the lowest unoccupied molecular orbital energy levels (LUMOs) and the band gaps (E_gs) of BTOF and BTOCz were −6.11, −2.66 and 3.45 eV, −5.86, −2.52 and 3.34 eV, respectively. The photoluminescence (PL) spectra of BTOF and BTOCz were peaked at 404 and 420 nm in film, and the photoluminescence quantum yields (Q_PLs) were 30% and 10% in toluene solution, respectively. BTOF and BTOCz showed strong intramolecular charge transfer (ICT) character, relatively high Q_PLs and deeper HOMO and LUMO levels compared with compounds BTF and BTCz. Compared with the symmetrical seven ring fused compounds FBTO and CzBTO, the asymmetrical five ring fused compounds BTOF and BTOCz showed relatively shallow HOMO levels, which can facilitate hole injection, and therefore, could be potential construction units in organic semiconductors.

Two large band-gap polymers (PTPACF and PTPA2CF) based on polytriphenylamine derivatives with the introduction of electron-withdrawing trifluoromethyl groups were designed and prepared by Suzuki polycondensation reaction. The chemical structures, thermal, optical and electrochemical properties were characterized in detail. From the UV-visible absorption spectra, the PTPACF and PTPA2CF showed the optical band gaps of 2.01 and 2.07 eV, respectively. The cyclic voltammetry (CV) measurement displayed the deep highest occupied molecular orbital (HOMO) energy levels of −5.33 and −5.38 eV for PTPACF and PTPA2CF, respectively. The hole mobilities, determined by field-effect transistor characterization, were 2.5 × 10⁻³ and 1.1 × 10⁻³ cm² V⁻¹ S⁻¹ for PTPACF and PTPA2CF, respectively. The polymer solar cells (PSCs) were tested under the conventional device structure of ITO/PEDOT:PSS/polymer:PC₇₁BM/PFN/Al. All of the PSCs showed the high open circuit voltages (V_ocs) with the values approaching 1 V. The PTPACF and PTPA2CF based PSCs gave the power conversion efficiencies (PCEs) of 3.24% and 2.40%, respectively. Hence, it is a reliable methodology to develop high-performance large band-gap polymer donors with high V_ocs through the feasible side-chain modification.