Side Chain Influence on the Morphology and Photovoltaic Performance of 5-Fluoro-6-alkyloxybenzothiadiazole and Benzodithiophene Based Conjugated Polymers

Three conjugated polymers (P1-P3) with benzodithiophene derivatives as the donor unit, 5-fluoro-6-(2-hexyldecyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5] thiadiazole as the acceptor unit and thiophene as the spacer were designed, synthesized, and used as donor materials for polymer solar cells (PSCs). The influence of side chains at the benzodithiophene unit on the performance of PSCs was investigated. PSCs with the blend of P2:PC71BM (1:2, by weight) as the active layer show the highest power conversion efficiency (PCE) of 6.88%, with an open circuit voltage (Voc) of 0.76 V, a short circuit current (Jsc) of 14.67 mA/cm(2), and a fill factor (FF) of 0.62. Our research revealed that the variation of side chains had a great influence on the morphology of blend films, which is crucial to the performance of PSCs. As indicated by transmission electron microscopy, the blends of P1:PC71BM (1:2) and P2:PC71BM (1:2) formed nanofibers, whereas the blends of P3:PC71BM (1:2) formed spherical domains. Therefore, we concluded that formation of a more interpenetrating phase-separated donor-acceptor network with a larger interfacial area and proper percolation in the blends from P1 to P2 is mainly responsible for better performance in the corresponding devices.

Synthesis and photovoltaic properties of A–D–A type non-fullerene acceptors containing isoindigo terminal units

Four solution-processable acceptor–donor–acceptor structured organic molecules with isoindigo as terminal acceptor units and different aromatic rigid planar cores as donor units were designed and synthesized as the acceptor materials in organic solar cells (OSCs).

Pyrene terminal functionalized perylene diimide as non-fullerene acceptors for bulk heterojunction solar cells

Two perylene diimide based small molecules with different terminal groups of pyrene andtert-butyl pyrene were developed as acceptor materials in organic solar cells.

Novel Hybrid Ligands for Passivating PbS Colloidal Quantum Dots to Enhance the Performance of Solar Cells

We developed novel hybrid ligands to passivate PbS colloidal quantum dots (CQDs), and two kinds of solar cells based on as-synthesized CQDs were fabricated to verify the passivation effects of the ligands. It was found that the ligands strongly affected the optical and electrical properties of CQDs, and the performances of solar cells were enhanced strongly. The optimized hybrid ligands, oleic amine/octyl-phosphine acid/CdCl₂ improved power conversion efficiency (PCE) to much higher of 3.72 % for Schottky diode cell and 5.04 % for p-n junction cell. These results may be beneficial to design passivation strategy for low-cost and high-performance CQDs solar cells.

Star-shaped isoindigo-based small molecules as potential non-fullerene acceptors in bulk heterojunction solar cells

Two novel star-shaped isoindigo-based small molecules with different cores of triphenylamine and benzene were designed and synthesized as non-fullerene acceptor materials in organic solar cells.

An alkylthieno-2-yl flanked dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene-based low band gap conjugated polymer for high performance photovoltaic solar cells

A conjugated polymer from 5,10-dialkylthieno-2-yl-dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene and naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole derivative, was synthesized, and inverted polymer solar cells with a power conversion efficiency of 7.52% was achieved.

Correlation of structure and photovoltaic performance of benzo[1,2-b:4,5-b′]dithiophene copolymers alternating with different acceptors

The PBDTT–TTz/PC₆₁BM (1 : 2) devices with PFN as the cathode interfacial layer delivered a power conversion efficiency of 2.60% for polymer solar cells.

Enhancement of open-circuit voltage and the fill factor in CdTe nanocrystal solar cells by using interface materials

Interface states influence the operation of nanocrystal (NC) solar cell carrier transport, recombination and energetic mechanisms. In a typical CdTe NC solar cell with a normal structure of a ITO/p-CdTe NCs/n-acceptor (or without)/Al configuration, the contact between the ITO and CdTe is a non-ohm contact due to a different work function (for an ITO, the value is ~4.7 eV, while for CdTe NCs, the value is ~5.3 eV), which results in an energetic barrier at the ITO/CdTe interface and decreases the performance of the NC solar cells. This work investigates how interface materials (including Au, MoO(x) and C₆₀) affect the performance of NC solar cells. It is found that devices with interface materials have shown higher V(oc) than those without interface materials. For the case in which we used Au as an interface, we obtained a high open-circuit voltage of 0.65 V, coupled with a high fill factor (62%); this resulted in a higher energy conversion efficiency (ECE) of 5.3%, which showed a 30% increase in the ECE compared with those without the interlayer. The capacitance measurements indicate that the increased V(oc) in the case in which Au was used as the interface is likely due to good ohm contact between the Au's and the CdTe NCs' thin film, which decreases the energetic barrier at the ITO/CdTe interface.

Prognostic nomograms for predicting survival and distant metastases in locally advanced rectal cancers

Aim

To develop prognostic nomograms for predicting outcomes in patients with locally advanced rectal cancers who do not receive preoperative treatment.

Materials and Methods

A total of 883 patients with stage II–III rectal cancers were retrospectively collected from a single institution. Survival analyses were performed to assess each variable for overall survival (OS), local recurrence (LR) and distant metastases (DM). Cox models were performed to develop a predictive model for each endpoint. The performance of model prediction was validated by cross validation and on an independent group of patients.

Results

The 5-year LR, DM and OS rates were 22.3%, 32.7% and 63.8%, respectively. Two prognostic nomograms were successfully developed to predict 5-year OS and DM-free survival rates, with c-index of 0.70 (95% CI = [0.66, 0.73]) and 0.68 (95% CI = [0.64, 0.72]) on the original dataset, and 0.76 (95% CI = [0.67, 0.86]) and 0.73 (95% CI = [0.63, 0.83]) on the validation dataset, respectively. Factors in our models included age, gender, carcinoembryonic antigen value, tumor location, T stage, N stage, metastatic lymph nodes ratio, adjuvant chemotherapy and chemoradiotherapy. Predicted by our nomogram, substantial variability in terms of 5-year OS and DM-free survival was observed within each TNM stage category.

Conclusions

The prognostic nomograms integrated demographic and clinicopathological factors to account for tumor and patient heterogeneity, and thereby provided a more individualized outcome prognostication. Our individualized prediction nomograms could help patients with preoperatively under-staged rectal cancer about their postoperative treatment strategies and follow-up protocols.

White polymer light-emitting devices for solid-state lighting: materials, devices, and recent progress

White polymer light-emitting devices (WPLEDs) have become a field of immense interest in both scientific and industrial communities. They have unique advantages such as low cost, light weight, ease of device fabrication, and large area manufacturing. Applications of WPLEDs for solid-state lighting are of special interest because about 20% of the generated electricity on the earth is consumed by lighting. To date, incandescent light bulbs (with a typical power efficiency of 12-17 lm W(-1) ) and fluorescent lamps (about 40-70 lm W(-1) ) are the most widely used lighting sources. However, incandescent light bulbs convert 90% of their consumed power into heat while fluorescent lamps contain a small but significant amount of toxic mercury in the tube, which complicates an environmentally friendly disposal. Remarkably, the device performances of WPLEDs have recently been demonstrated to be as efficient as those of fluorescent lamps. Here, we summarize the recent advances in WPLEDs with special attention paid to the design of novel luminescent dopants and device structures. Such advancements minimize the gap (for both efficiency and stability) from other lighting sources such as fluorescent lamps, light-emitting diodes based on inorganic semiconductors, and vacuum-deposited small-molecular devices, thus rendering WPLEDs equally competitive as these counterparts currently in use for illumination purposes.

Recent advances in polymer solar cells: realization of high device performance by incorporating water/alcohol-soluble conjugated polymers as electrode buffer layer

This Progress Report highlights recent advances in polymer solar cells with special attention focused on the recent rapid-growing progress in methods that use a thin layer of alcohol/water-soluble conjugated polymers as key component to obtain optimized device performance, but also discusses novel materials and device architectures made by major prestigious institutions in this field. We anticipate that due to drastic improvements in efficiency and easy utilization, this method opens up new opportunities for PSCs from various material systems to improve towards 10% efficiency, and many novel device structures will emerge as suitable architectures for developing the ideal roll-to-roll type processing of polymer-based solar cells.

A prognostic nomogram for predicting recurrence and survival in rectal cancers without neoadjuvant treatment

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Background: To develop a prognostic nomogram for predicting recurrence and survival in patients with locally advanced rectal cancers that were not able to receive preoperative treatment. Methods: A total of 887 patients with AJCC (7th edition) stage II-III rectal cancers were retrospectively collected from a single institution. All patients did not receive any preoperative treatment before curative resection of the primary tumor. Cox proportional hazards model was performed to develop the predictive model for OS. Results: The 5-year local recurrence rate, distant metastases rate, and overall survival rate were 22.2%, 32.9%, and 63.9%, respectively. A prognostic nomogram was successfully developed to predicting patients’ 5-year overall survival, with a concordance index of 0.7. Factors in this model included patients’ age, gender, CEA value, tumor location, T stage, N stage, metastatic lymph nodes ratio, lymphvascular invasion, perineural invasion, adjuvant chemotherapy, adjuvant chemoradiotherapy. Our nomogram improved the predicting accuracy of current AJCC stage system (7th edition). Conclusions: The prognostic nomogram integrated patients demographic and clinicopathologic factors, which is better able to account for tumor and patient heterogeneity. Our individualized prediction nomogram could help physicians counsel and advise patients about their personalized treatment strategies and follow-up protocols. [Table: see text]

Is adjuvant radiotherapy warranted in resected pT1-2 node-positive rectal cancer?

Background

Stage T1-2 rectal cancers are unlikely to have lymph node metastases and neoadjuvant therapy is not routinely administered. Postoperative management is controversial if lymph node metastases are detected in the resected specimen. We studied the outcomes of patients with pT1-2 node-positive rectal cancer in order to determine whether adjuvant radiotherapy was beneficial.

Methods

We conducted a retrospective analysis of 284 patients with pathological T1-2 node-positive rectal cancer from a single institution. Outcomes, including local recurrence (LR), distant metastasis (DM), disease free survival (DFS) and overall survival (OS), were studied in patients with detailed TN staging and different adjuvant treatment modalities.

Results

The overall 5-year LR, DM, DFS and OS rates for all patients were 12.5%, 32.9%, 36.4% and 76.8%, respectively. Local control was inferior among patients who received no adjuvant therapy. Patients could be divided into three risk subsets: Low-risk, T1N1; Intermediate-risk, T2N1 and T1N2; and High-risk, T2N2. The 5-year LR rates were 5.3%, 9.8% and 26.4%, respectively (p = 0.005). In High-risk patients, addition of radiotherapy achieved a 5-year LR rate of 9.1%, compared 34.8% without radiotherapy.

Conclusions

In our study, we provide the detailed outcomes and preliminary survival analysis in a relatively infrequent subset of rectal cancer. Three risk subsets could be identified based on local control for pT1-2 node positive rectal cancer. Postoperative treatment needs to be individualized for patients with pT1-2 node-positive rectal cancer.

Monodisperse Low-Bandgap Macromolecule-Based 5,5'-Bibenzo[c][1,2,5]thiadiazole Swivel Cruciform for Organic Solar Cells

A novel low bandgap star-like macromolecule was synthesized and applied as electron donor material in the bulk heterojunction solar cells, in which the 5,5'-bibenzo[c][1,2,5]thiadiazole was used as the central node, in conjunction with four conjugated donor-acceptor arms. Compared with the corresponding small molecule with first generation arms, the macromolecule with second generation branches exhibited significantly enhanced photovoltaic device performances (blended with PC71BM as the active layer) due to dramatically improved short-circuit current density (J_sc) and fill factor (FF). The improvement in J_sc and FF can be attributed to the more broad absorption and the more favorable phase separation when comparing a monodisperse macromolecule with the second generation arms (SFTBT) with a small molecule with first generation branches (DFTBT).

Different responses to mechanical injury in neonatal and adult ovine articular cartilage

Background

Articular cartilage injury remains a major challenge in orthopedic surgery. This study aimed to identify differences in gene expression and molecular responses between neonatal and adult articular cartilage during the healing of an injury.

Methods

An established in vitro model was used to compare the transcriptional response to cartilage injury in neonatal and adult sheep by microarray analysis of gene expression. Total RNA was isolated from tissue samples, linearly amplified, and 15,208 ovine probes were applied to cDNA microarray. Validation for selected genes was obtained by real-time quantitative polymerase chain reaction (RT-qPCR).

Results

We found 1,075 (11.6%) differentially expressed probe sets in adult injured cartilage relative to normal cartilage. A total of 1,016 (11.0%) probe sets were differentially expressed in neonatal injured cartilage relative to normal cartilage. A total of 1,492 (16.1%) probe sets were differentially expressed in adult normal cartilage relative to neonatal normal cartilage. A total of 1,411 (15.3%) probe sets were differentially expressed in adult injured cartilage relative to neonatal injured cartilage. Significant functional clusters included genes associated with wound healing, articular protection, inflammation, and energy metabolism. Selected genes (PPARG, LDH, TOM, HIF1A, SMAD7, and NF-κB) were also found and validated by RT-qPCR.

Conclusions

There are significant differences in gene expression between neonatal and adult ovine articular cartilage following acute injury. They are partly due to intrinsic differences in the process of development, and partly to different biological responses to mechanical trauma between neonatal and adult articular cartilage.

Tolerability and outcomes of radiotherapy or chemoradiotherapy for rectal cancer in elderly patients aged 70 years and older

PURPOSE

To assess the safety and outcomes of radiotherapy (RT) or chemoradiotherapy (CRT) in elderly patients (≥70) with rectal cancer.

METHODS

Elderly patients aged 70 and older with rectal cancer, who were treated with RT or CRT at a single institution, were retrospectively analyzed. Performance status (KPS and ECOG score) and comorbidity (Charlson comorbidity index) were calculated, and their correlation with treatment toxicity and overall survival were studied. Risk factors for overall survival were investigated using univariate and multivariate survival analysis.

RESULTS

A total of 126 patients with locally advanced disease, local recurrence or synchronous metastasis were included, with a 3-year OS rate of 48.1%. Scheduled dosage of radiation was delivered to 69% of patients. Grade 3 toxicities occurred more often in patients treated with CRT versus RT. The occurrence of grade 3 toxicities was not related to KPS score, ECOG score, number of comorbidities, and Charlson score. Multivariate analysis found that only age and Charlson score were independent prognostic factors for predicting patients' 3-year OS. The 3-year OS rate was significantly higher in patients with Charlson score <4 vs Charlson score ≥4 (71.1% vs. 26.4%, P=0.0003).

CONCLUSIONS

Although toxicities may be significant, elderly patients with rectal cancer of varied stages can be safely treated with RT or CRT with careful monitoring and frequent modification of treatment. Except for patients' age, Charlson comorbidity index may be helpful in assessing patients' outcomes in elderly patients with rectal cancer.