Near-Infrared-Absorbing Indolizine-Porphyrin Push-Pull Dye for Dye-Sensitized Solar Cells

Porphyrins are attractive chromophores for application in dye-sensitized solar cells (DSCs), as judicious tuning of donor-acceptor properties can enable excellent near-infrared (NIR) absorption and exceptional device performance. Here, we report a porphyrin-based dye (SM85) conjugated to the planar strong electron donor, indolizine, designed to extend absorption further into the NIR region by inducing π-π interactions such as head-to-tail dye aggregation. The optoelectronic consequences of indolizine incorporation in SM85 include raising the ground-state oxidation potential and broadening and red-shifting ultraviolet-visible-NIR absorptions, along with increased molar absorptivity when compared to the dye SM315. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations confirm the push-pull character of SM85, which features an overlap of frontier occupied and unoccupied orbitals. Steady-state spectrophotometric analyses reveal the presence of solution aggregates via absorption and emission spectroscopies. Aggregate modes were probed by DFT and TD-DFT analyses, and plausible models are presented. SM85-based DSC devices demonstrate a 5.7% power conversion efficiency (PCE) at full sun (7.4% PCE at 10% sun) with an exceptional improvement to the incident photon-to-current conversion onset at ∼850 nm. Current dynamics measurements, time-correlated single photon counting, and computational analyses are used to better understand device performances. This study puts forward a novel intramolecular charge-transfer porphyrin system with a dramatic shift into the NIR region, as is needed for nonprecious metal-based sensitizers, and provides an example of controlled, donor-acceptor-mediated aggregation as a complementary strategy to traditional donor-acceptor modifications to single-molecule π-systems in accessing enhancements in long wavelength light harvesting in molecular-based optoelectronic devices.

Value Frameworks in Oncology: Comparative Analysis and Implications to the Pharmaceutical Industry

BACKGROUND

As the cost of oncology care continues to rise, composite value models that variably capture the diverse concerns of patients, physicians, payers, policymakers, and the pharmaceutical industry have begun to take shape.

OBJECTIVES

To review the capabilities and limitations of 5 of the most notable value frameworks in oncology that have emerged in recent years and to compare their relative value and application among the intended stakeholders.

METHODS

We compared the methodology of the American Society of Clinical Oncology (ASCO) Value Framework (version 2.0), the National Comprehensive Cancer Network Evidence Blocks, Memorial Sloan Kettering Cancer Center DrugAbacus, the Institute for Clinical and Economic Review Value Assessment Framework, and the European Society for Medical Oncology Magnitude of Clinical Benefit Scale, using a side-by-side comparative approach in terms of the input, scoring methodology, and output of each framework. In addition, we gleaned stakeholder insights about these frameworks and their potential real-world applications through dialogues with physicians and payers, as well as through secondary research and an aggregate analysis of previously published survey results.

RESULTS

The analysis identified several framework-specific themes in their respective focus on clinical trial elements, breadth of evidence, evidence weighting, scoring methodology, and value to stakeholders. Our dialogues with physicians and our aggregate analysis of previous surveys revealed a varying level of awareness of, and use of, each of the value frameworks in clinical practice. For example, although the ASCO Value Framework appears nascent in clinical practice, physicians believe that the frameworks will be more useful in practice in the future as they become more established and as their outputs are more widely accepted.

CONCLUSIONS

Along with patients and payers, who bear the burden of treatment costs, physicians and policymakers have waded into the discussion of defining value in oncology care, as well as pharmaceutical companies that seek to understand the impact of these value frameworks on each stakeholder, as they model the value and financial threshold of innovative, high-cost drugs.