Positional irradiance measurement: characterization of spectrum-splitting and concentrating optics for photovoltaics

Multijunction photovoltaics enable significantly improved efficiency over their single junction analogues by mitigating unabsorbed sub-bandgap photons and voltage loss to carrier thermalization. Lateral spectrum-splitting configurations promise further increased efficiency through relaxation of the lattice- and current-matching requirements of monolithic stacks, albeit at the cost of increased optical and electrical complexity. Consequently, in order to achieve an effective spectrum-splitting photovoltaic configuration it is essential that all optical losses and photon misallocation be characterized and subsequently minimized. We have developed a characterization system that enables us to map the spatial, spectral, and angular distribution of illumination incident on the subcell reception plane or emerging from any subset of the concentrating and splitting optics. This positional irradiance measurement system (PIMS) comprises four motorized stages assembled in an X-Z-RY configuration with three linear degrees of freedom and one rotational degree of freedom, on which we mount an optical fiber connected to a set of spectrometers covering the solar spectrum from 280-1700 nm. In combination with a xenon arc lamp solar simulator with a divergence half angle of 1.3 degrees, we are able to characterize our optics across the full spectrum of our photovoltaic subcells with close agreement to outdoor conditions. We have used this tool to spectrally characterize holographic diffraction efficiency versus diffraction angle; multilayer dielectric filter transmission and reflection efficiency versus filter incidence angle; and aspheric lens chromatic aberration versus optic-to-receiver separation distance. These examples illustrate the versatility of the PIMS in characterizing optical performance relevant to both spectrum-splitting and traditional multijunction photovoltaics. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Medication adherence and costs of medical care among patients with Parkinson’s disease: an observational study using electronic medical records

Background: Adherence to antiparkinsonian drugs (APDs) is critical for patients with Parkinson’s disease (PD), for which medication is the main therapeutic strategy. Previous studies have focused on specific disorders in a single system when assessing clinical factors affecting adherence to PD treatment, and no international comparative data are available on the medical costs for Chinese patients with PD. The present study aimed to evaluate medication adherence and its associated factors among Chinese patients with PD using a systematic approach and to explore the impact of adequate medication adherence on direct medical costs. Methods: A retrospective analysis was conducted using the electronic medical records of patients with PD from a medical center in China. Patients with a minimum of two APD prescriptions from January 1, 2016 to August 15, 2018 were included. Medication possession ratio (MPR) and proportion of days covered were used to measure APD adherence. Multiple linear regression analysis was used to identify factors affecting APD adherence. Gamma regression analysis was used to explore the impact of APD adherence on direct medical costs. Results: In total, 1,712 patients were included in the study, and the mean MPR was 0.68 (± 0.25). Increased number of APDs and all medications, and higher daily levodopa-equivalent doses resulted in higher MPR (mean difference [MD] = 0.04 [0.03–0.05]; MD = 0.02 [0.01–0.03]; MD = 0.03 [0.01–0.04], respectively); combined digestive system diseases, epilepsy, or older age resulted in lower MPR (MD = -0.06 [-0.09 to -0.03]; MD = -0.07 [-0.14 to -0.01]; MD = -0.02 [-0.03 to -0.01], respectively). Higher APD adherence resulted in higher direct medical costs, including APD and other outpatient costs. For a 0.3 increase in MPR, the two costs increased by $34.42 ($25.43–$43.41) and$14.63 ($4.86–$24.39) per year, respectively. Conclusions: APD adherence rate among Chinese patients with PD was moderate and related primarily to age, comorbidities, and healthcare costs. The factors should be considered when prescribing APDs

Towards Deeply Unified Depth-aware Panoptic Segmentation with Bi-directional Guidance Learning

Depth-aware panoptic segmentation is an emerging topic in computer vision which combines semantic and geometric understanding for more robust scene interpretation. Recent works pursue unified frameworks to tackle this challenge but mostly still treat it as two individual learning tasks, which limits their potential for exploring cross-domain information. We propose a deeply unified framework for depth-aware panoptic segmentation, which performs joint segmentation and depth estimation both in a per-segment manner with identical object queries. To narrow the gap between the two tasks, we further design a geometric query enhancement method, which is able to integrate scene geometry into object queries using latent representations. In addition, we propose a bi-directional guidance learning approach to facilitate cross-task feature learning by taking advantage of their mutual relations. Our method sets the new state of the art for depth-aware panoptic segmentation on both Cityscapes-DVPS and SemKITTI-DVPS datasets. Moreover, our guidance learning approach is shown to deliver performance improvement even under incomplete supervision labels.Comment: to be published in ICCV 202

Autonomous Light Management in Flexible Photoelectrochromic Films Integrating High Performance Silicon Solar Microcells

Commercial smart window technologies for dynamic light and heat management in building and automotive environments traditionally rely on electrochromic (EC) materials powered by an external source. This design complicates building-scale installation requirements and substantially increases costs for applications in retrofit construction. Self-powered photoelectrochromic (PEC) windows are an intuitive alternative wherein a photovoltaic (PV) material is used to power the electrochromic device, which modulates the transmission of the incident solar flux. The PV component in this application must be sufficiently transparent and produce enough power to efficiently modulate the EC device transmission. Here, we propose Si solar microcells (μ-cells) that are i) small enough to be visually transparent to the eye, and ii) thin enough to enable flexible PEC devices. Visual transparency is achieved when Si μ-cells are arranged in high pitch (i.e. low-integration density) form factors while maintaining the advantages of a single-crystalline PV material (i.e., long lifetime and high performance). Additionally, the thin dimensions of these Si μ-cells enable fabrication on flexible substrates to realize these flexible PEC devices. The current work demonstrates this concept using WO₃ as the EC material and V₂O₅ as the ion storage layer, where each component is fabricated via sol-gel methods that afford improved prospects for scalability and tunability in comparison to thermal evaporation methods. The EC devices display fast switching times, as low as 8 seconds, with a modulation in transmission as high as 33%. Integration with two Si μ-cells in series (affording a 1.12 V output) demonstrates an integrated PEC module design with switching times of less than 3 minutes, and a modulation in transmission of 32% with an unprecedented EC:PV areal ratio

Micro-optical Tandem Luminescent Solar Concentrators

Traditional concentrating photovoltaic (CPV) systems utilize multijunction cells to minimize thermalization losses, but cannot efficiently capture diffuse sunlight, which contributes to a high levelized cost of energy (LCOE) and limits their use to geographical regions with high direct sunlight insolation. Luminescent solar concentrators (LSCs) harness light generated by luminophores embedded in a light-trapping waveguide to concentrate light onto smaller cells. LSCs can absorb both direct and diffuse sunlight, and thus can operate as flat plate receivers at a fixed tilt and with a conventional module form factor. However, current LSCs experience significant power loss through parasitic luminophore absorption and incomplete light trapping by the optical waveguide. Here we introduce a tandem LSC device architecture that overcomes both of these limitations, consisting of a PLMA polymer layer with embedded CdSe/CdS quantum dot (QD) luminophores and InGaP micro-cells, which serve as a high bandgap absorber on top of a conventional Si photovoltaic. We experimentally synthesize CdSe/CdS QDs with exceptionally high quantum-yield (99%) and ultra-narrowband emission optimally matched to fabricated III-V InGaP micro-cells. Using a Monte Carlo ray-tracing model, we show the radiative limit power conversion efficiency for a module with these components to be 30.8% diffuse sunlight conditions. These results indicate that a tandem LSC-on-Si architecture could significantly improve upon the efficiency of a conventional Si photovoltaic module with simple and straightforward alterations of the module lamination steps of a Si photovoltaic manufacturing process, with promise for widespread module deployment across diverse geographical regions and energy markets

Autonomous Light Management in Flexible Photoelectrochromic Films Integrating High Performance Silicon Solar Microcells

Commercial smart window technologies for dynamic light and heat management in building and automotive environments traditionally rely on electrochromic (EC) materials powered by an external source. This design complicates building-scale installation requirements and substantially increases costs for applications in retrofit construction. Self-powered photoelectrochromic (PEC) windows are an intuitive alternative wherein a photovoltaic (PV) material is used to power the electrochromic device, which modulates the transmission of the incident solar flux. The PV component in this application must be sufficiently transparent and produce enough power to efficiently modulate the EC device transmission. Here, we propose Si solar microcells (μ-cells) that are i) small enough to be visually transparent to the eye, and ii) thin enough to enable flexible PEC devices. Visual transparency is achieved when Si μ-cells are arranged in high pitch (i.e. low-integration density) form factors while maintaining the advantages of a single-crystalline PV material (i.e., long lifetime and high performance). Additionally, the thin dimensions of these Si μ-cells enable fabrication on flexible substrates to realize these flexible PEC devices. The current work demonstrates this concept using WO₃ as the EC material and V₂O₅ as the ion storage layer, where each component is fabricated via sol-gel methods that afford improved prospects for scalability and tunability in comparison to thermal evaporation methods. The EC devices display fast switching times, as low as 8 seconds, with a modulation in transmission as high as 33%. Integration with two Si μ-cells in series (affording a 1.12 V output) demonstrates an integrated PEC module design with switching times of less than 3 minutes, and a modulation in transmission of 32% with an unprecedented EC:PV areal ratio