Tethered Helical Ladder-Type Aromatic Lactams.

Tethered nonplanar aromatics (TNAs) make up an important class of nonplanar aromatic compounds showing unique features. However, the knowledge on the synthesis, structures, and properties of TNAs remains insufficient. In this work, a new type of TNAs, the tethered aromatic lactams, is synthesized via Pd-catalyzed consecutive intramolecular direct arylations. These molecules possess a helical ladder-type conjugated system of up to 13 fused rings. The overall yields ranged from 3.4 to 4.3%. The largest of the tethered aromatic lactams, 6L-Bu-C14, demonstrates a guest-adaptive hosting capability of TNAs for the first time. When binding fullerene guests, the cavity of 6L-Bu-C14 became more circular to better accommodate spherical fullerene molecules. The host-guest interaction is thoroughly studied by X-ray crystallography, theoretical calculations, fluorescence titration, and nuclear magnetic resonance (NMR) titration experiments. 6L-Bu-C14 shows stronger binding with C70 than with C60 due to the better convex-concave π-π interaction. P and M enantiomers of all tethered aromatic lactams show distinct and persistent chiroptical properties and demonstrate the potential of chiral TNAs as circularly polarized luminescence (CPL) emitters.

Creating a Dual-Functional 2D Perovskite Layer at the Interface to Enhance the Performance of Flexible Perovskite Solar Cells.

Flexible perovskite solar cells (f-PSCs) have been attracting tremendous attention due to their potentially commercial prospects in flexible energy system and mobile energy system. Reducing the energy barriers and charge extraction losses at the interfaces between perovskite and charge transport layers is essential to improve both efficiency and stability of f-PSCs. Herein, 4-trifluoromethylphenylethylamine iodide (CF3 PEAI) is introduced to form a 2D perovskite at the interface between perovskite and hole transport layer (HTL). It is found that the 2D perovskite plays a dual-functional role in aligning energy band between perovskite and HTL and passivating the traps in the 3D perovskite, thus reducing energy loss and charge carrier recombination at the interface, facilitating the hole transfer from perovskite to the Spiro-OMeTAD. Consequently, the photovoltaic performance of f-PSCs is significantly improved, leading to a power conversion efficiency (PCE) of 21.1% and a certified PCE of 20.5%. Furthermore, the long-term stability of f-PSCs is greatly improved through the protection of 2D perovskite layer to the underlying 3D perovskite. This work provides an excellent strategy to produce efficient and stable f-PSCs, which will accelerate their potential applications.

Drop-Casting to Make Efficient Perovskite Solar Cells under High Humidity.

Drop-casting was used to make MAPbI3 films for solar cells. The crystal growth in drop-cast MAPbI3 films was regulated by adjusting temperature. A mechanism for the formation of different morphology was proposed by combining in situ crystal-growth study with XRD measurements. The crystals in the films made at low temperature (60 °C) and high temperature (≥120 °C) are (110) and (200) oriented, respectively. The different crystal growth mode leads to quite different film morphology. Compared with spin-coating, drop-casting shows much better tolerance to humidity. MAPbI3 solar cells made under 88 % humidity delivered a PCE of 18.17 %, which is the highest PCE for perovskite solar cells made under >70 % humidity without antisolvent assistance.

Controlling Homogenous Spherulitic Crystallization for High-Efficiency Planar Perovskite Solar Cells Fabricated under Ambient High-Humidity Conditions.

The influence of precursor solution properties, fabrication environment, and antisolvent properties on the microstructural evolution of perovskite films is reported. First, the impact of fabrication environment on the morphology of methyl ammonium lead iodide (MAPbI3 ) perovskite films with various Lewis-base additives is reported. Second, the influence of antisolvent properties on perovskite film microstructure is investigated using antisolvents ranging from nonpolar heptane to highly polar water. This study shows an ambient environment that accelerates crystal growth at the expense of nucleation and introduces anisotropies in crystal morphology. The use of antisolvents enhances nucleation but also influences ambient moisture interaction with the precursor solution, resulting in different crystal morphology (shape, size, dispersity) in different antisolvents. Crystal morphology, in turn, dictates film quality. A homogenous spherulitic crystallization results in pinhole-free films with similar microstructure irrespective of processing environment. This study further demonstrates propyl acetate, an environmentally benign antisolvent, which can induce spherulitic crystallization under ambient environment (52% relative humidity, 25 °C). With this, planar perovskite solar cells with ≈17.78% stabilized power conversion efficiency are achieved. Finally, a simple precipitation test and in situ crystallization imaging under an optical microscope that can enable a facile a priori screening of antisolvents is shown.

Association Between BMI and Recurrence of Primary Spontaneous Pneumothorax.

BACKGROUND: Whether body mass index (BMI) is a significant risk factor for recurrence of primary spontaneous pneumothorax (PSP) remains controversial. The purpose of this study was to examine whether BMI and other factors are linked to risk of PSP recurrence. METHODS: A consecutive cohort of 273 patients was retrospectively evaluated. Patients were divided into those who experienced recurrence (n = 81) and those who did not (n = 192), as well as into those who had low BMI (n = 75) and those who had normal or elevated BMI (n = 198). The two pairs of groups were compared in terms of baseline data, and Cox proportional hazards modeling was used to identify predictors of PSP recurrence. RESULTS: Rates of recurrence among all 273 patients were 20.9% at 1 year, 23.8% at 2 years, and 28.7% at 5 years. Univariate analysis identified the following significant predictors of PSP recurrence: height, weight, BMI, size of pneumothorax, and treatment modality. Multivariate analyses identified several risk factors for PSP recurrence: low BMI, pneumothorax size ≥50%, and non-surgical treatment. Kaplan-Meier survival analysis indicated that patients with low BMI showed significantly lower recurrence-free survival than patients with normal or elevated BMI (P < 0.001). CONCLUSIONS: Low BMI, pneumothorax size ≥50%, and non-surgical treatment were risk factors for PSP recurrence in our cohort. Low BMI may be a clinically useful predictor of PSP recurrence.

Effect of neoadjuvant chemoradiotherapy on perioperative immune function of patients with locally advanced esophageal cancer.

This study aims to evaluate the effect of neoadjuvant chemoradiotherapy (NCRT) on perioperative immune function during surgery to treat resectable locally advanced esophageal cancer. Records were retrospectively analyzed for 220 patients with locally advanced esophageal cancer, of whom 112 received surgery alone and 98 received neoadjuvant NCRT plus surgery. The two groups were compared in terms of proportions of CD3+, CD4+, CD8+, and natural kill (NK) cells, as well as the ratio of CD4+ to CD8+ cells. These measurements were made using flow cytometry on preoperative day 1 and on postoperative days 1 and 7. Subgroup analysis were performed in terms of degrees of pathological response of NCRT. When the entire NCRT and no-NCRT (surgery alone) cohorts were compared, no significant differences in propocrtions of CD3+, CD4+, CD8+, or NK cells or in the CD4+/CD8+ ratio occurred at any of the three time points. Similar results were obtained using the subgroup of NCRT patients who were NCRT-sensitive, but the subgroup of NCRT-insensitive patients showed significantly lower CD4+ and NK proportions and lower CD4+/CD8+ ratio than the no-NCRT group. Our findings suggest that NCRT does not affect perioperative immune function in patients who are NCRT-sensitive, but it does significantly reduce such function in patients who are NCRT-insensitive.

Lead-free Perovskite Materials (NH4 )3 Sb2 Ix Br9-x.

A family of perovskite light absorbers (NH4 )3 Sb2 Ix Br9-x (0≤x≤9) was prepared. These materials show good solubility in ethanol, a low-cost, hypotoxic, and environmentally friendly solvent. The light absorption of (NH4 )3 Sb2 Ix Br9-x films can be tuned by adjusting I and Br content. The absorption onset for (NH4 )3 Sb2 Ix Br9-x films changes from 558 nm to 453 nm as x changes from 9 to 0. (NH4 )3 Sb2 I9 single crystals were prepared, exhibiting a hole mobility of 4.8 cm2 V-1 s-1 and an electron mobility of 12.3 cm2 V-1 s-1 . (NH4 )3 Sb2 I9 solar cells gave an open-circuit voltage of 1.03 V and a power conversion efficiency of 0.51 %.

Solution-Processed Cu2O and CuO as Hole Transport Materials for Efficient Perovskite Solar Cells.

Solution-processed Cu2 O and CuO are used as hole transport materials in perovskite solar cells. The cells show significantly enhanced open circuit voltage Voc, short-circuit current Jsc, and power conversion efficiency (PCE) compared with PEDOT cells. A PCE of 13.35% and good stability are achieved for Cu2O cells, making Cu2O a promising material for further application in perovskite solar cells.

A fused-ring acceptor unit in d-a copolymers benefits photovoltaic performance.

Pentacyclic lactam acceptor unit TPTI invented by our group is proved to be a good building block for efficient D-A copolymers used in organic solar cells. Here, two D-A copolymers PBTTPTI and PTTTPTI are developed by copolymerizing TPTI with 2,2'-bithiophene (BT) or thieno[3,2-b]thiophene (TT). PBTTPTI and PTTTPTI exhibit good solubility and strong interchain π-π interaction even in dilute solution. They possess deep HOMO levels (ca. -5.3 eV), partial crystallinity, and good hole mobilities. Blending with PC71 BM, PBTTPTI and PTTTPTI give decent power conversion efficiencies (PCE) up to 6.83% and 5.86%, with outstanding fill factors (FF) of 74.3% and 71.3%, respectively.

A highly efficient fullerene acceptor for polymer solar cells.

C70-based acceptors show great potential in polymer solar cells (PSCs). Two high-LUMO C70 acceptors, the 66π OQMF70 and the 64π bis-OQMF70, based on methano[70]fullerene (C70CH2) were developed. An outstanding power conversion efficiency (PCE) of 6.88% was obtained from OQMF70:P3HT solar cells.