Cuaderno abierto para la simulación de células solares de tres terminales de tipo transistor bipolar de heterounion

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: Los cuadernos abiertos (Open Notebooks), como los que pueden realizarse en el entorno Jupyter, son una herramienta excelente, no solo para documentar los programas que se implementan para realizar tal o cual cálculo, sino también para: a) facilitar la docencia sobre el asunto de que se trate, b) facilitar que terceros verifiquen con facilidad los cálculos realizados, c) posibilitar el cálculo interactivo. En el contexto del proyecto Europeo GRECO, dedicado al desarrollo de la ciencia e innovación responsable (RRI) aplicado al campo de la energía solar fotovoltaica, estamos desarrollando un “Open Notebook” para modelar analíticamente la denominada “célula solar de tres terminales de tipo transistor bipolar de heterounión”. En este trabajo describimos cómo acceder a dicho cuaderno, describimos el modelo utilizado para modelar dicha célula y comentamos algunas de las lecciones aprendidas en relación con su uso y el desarrollo de la ciencia abierta.ABSTRACT: Open Notebooks, such as those that can be made in the Jupyter environment, are an excellent tool, not only to document the codes that are implemented to perform this or that calculation, but also to: a) facilitate teaching on the subject in question, b) facilitate third parties to easily verify the calculations performed, c) enable interactive calculation. In the context of the European GRECO project, dedicated to the development of responsible research and innovation (RRI) in the field of photovoltaics, we are developing an “Open Notebook” to analytically model the so-called “three terminal heterojunction bipolar transistor solar cell”. In this paper, we describe how to access this Open Notebook, describe the model used to model said cell, and comment on some of the lessons learned in relation to its use and the development of open science.info:eu-repo/semantics/publishedVersio

Lithography-free electrical transport measurements on 2D materials by direct microprobing

We present a method to carry out electrical and optoelectronic measurements on 2D materials using carbon fiber microprobes to directly make electrical contacts with the 2D materials without damaging them. The working principle of this microprobing method is illustrated by measuring transport in MoS2 flakes in vertical (transport in the out-of-plane direction) and lateral (transport within the crystal plane) configurations, finding performances comparable to those reported for MoS2 devices fabricated by the conventional lithographic process. We also show that this method can be used with other 2D materials

Photodiodes based in La0.7Sr0.3MnO3/single layer MoS2 hybrid vertical heterostructures

The fabrication of artificial materials by stacking of individual two-dimensional (2D) materials is amongst one of the most promising research avenues in the field of 2D materials. Moreover, this strategy to fabricate new man-made materials can be further extended by fabricating hybrid stacks between 2D materials and other functional materials with different dimensionality making the potential number of combinations almost infinite. Among all these possible combinations, mixing 2D materials with transition metal oxides can result especially useful because of the large amount of interesting physical phenomena displayed separately by these two material families. We present a hybrid device based on the stacking of a single layer MoS2 onto a lanthanum strontium manganite (La0.7Sr0.3MnO3) thin film, creating an atomically thin device. It shows a rectifying electrical transport with a ratio of 103, and a photovoltaic effect with Voc up to 0.4 V. The photodiode behaviour arises as a consequence of the different doping character of these two materials. This result paves the way towards combining the efforts of these two large materials science communities

Gate tunable photovoltaic effect in MoS2 vertical p-n homostructures

p-n junctions based on vertically stacked single or few-layer transition metal dichalcogenides (TMDCs) have attracted substantial scientific interest. Due to the propensity of TMDCs to show exclusively one type of conductivity, n- or p-type, heterojunctions of different materials are typically fabricated to produce diode-like current rectification and photovoltaic response. Recently, artificial, stable and substitutional doping of MoS2 into n- and p-type materials has been demonstrated. MoS2 is an interesting material for use in optoelectronic applications due to its potential of low-cost production in large quantities, strong light-matter interactions and chemical stability. Here we report the characterization of the optoelectronic properties of vertical homojunctions made by stacking few-layer flakes of MoS2:Fe (n-type) and MoS2:Nb (p-type). The junctions exhibit a peak external quantum efficiency of 4.7% and a maximum open circuit voltage of 0.51 V; they are stable in air; and their rectification characteristics and photovoltaic response are in excellent agreement with the Shockley diode model. The gate-tunability of the maximum output power, the ideality factor and the shunt resistance indicate that the dark current is dominated by trap-assisted recombination and that the photocurrent collection depends strongly on the spatial extent of the space charge region. We demonstrate a response time faster than 80 ms and highlight the potential to integrate such devices into quasi-transparent and flexible optoelectronics

Highly responsive UV-photodetectors based on single electrospun TiO2 nanofibres

In this work we study the optoelectronic properties of individual TiO2 fibres produced through coupled sol-gel and electrospinning, by depositing them onto pre-patterned Ti/Au electrodes on SiO2/Si substrates. Transport measurements in the dark give a conductivity above 2 × 10-5 S, which increases up to 8 × 10-5 S in vacuum. Photocurrent measurements under UV-irradiation show high sensitivity (responsivity of 90 A W-1 for 375 nm wavelength) and a response time to illumination of ∼5 s, which is superior to state-of-the-art TiO2-based UV photodetectors. Both responsivity and response speed are higher in air than in vacuum, due to oxygen adsorbed on the TiO2 surface which traps photoexcited free electrons in the conduction band, thus reducing the recombination processes. The photodetectors are sensitive to light polarization, with an anisotropy ratio of 12%. These results highlight the interesting combination of large surface area and low 1D transport resistance in electrospun TiO2 fibres. The simplicity of the sol-gel/electrospinning synthesis method, combined with a fast response and high responsivity makes them attractive candidates for UV-photodetection in ambient conditions. We anticipate their high (photo) conductance is also relevant for photocatalysis and dye-sensitized solar cells

Evidence-based Assessment of Current and Emerging Bladder-sparing Therapies for Non-muscle-invasive Bladder Cancer After Bacillus Calmette-Guerin Therapy: A Systematic Review and Meta-analysis

CONTEXT: Currently, there is no standard of care for patients with non-muscle-invasive bladder cancer (NMIBC) who recur despite bacillus Calmette-Guerin (BCG) therapy. Although radical cystectomy is recommended, many patients decline to undergo or are ineligible to receive it. Multiple agents are being investigated for use in this patient population. OBJECTIVE: To systematically synthesize and describe the efficacy and safety of current and emerging treatments for NMIBC patients after treatment with BCG. EVIDENCE ACQUISITION: A systematic literature search of MEDLINE, Embase, and the Cochrane Controlled Register of Trials (period limited to January 2007-June 2019) was performed. Abstracts and presentations from major conference proceedings were also reviewed. Randomized controlled trials were assessed using the Cochrane risk of bias tool. Data for single-arm trials were pooled using a random-effect meta-analysis with the proportions approach. Trials were grouped based on the minimum number of prior BCG courses required before enrollment and further stratified based on the proportion of patients with carcinoma in situ (CIS). EVIDENCE SYNTHESIS: Thirty publications were identified with data from 23 trials for meta-analysis, of which 17 were single arm. Efficacy and safety outcomes varied widely across studies. Heterogeneity across trials was reduced in subgroup analyses. The pooled 12-mo response rates were 24% (95% confidence interval [CI]: 16-32%) for trials with two or more prior BCG courses and 36% (95% CI: 25-47%) for those with one or more prior BCG courses. In a subgroup analysis, inclusion of >/=50% of patients with CIS was associated with a lower response. CONCLUSIONS: The variability in efficacy and safety outcomes highlights the need for consistent endpoint reporting and patient population definitions. With promising emerging treatments currently in development, efficacious and safe therapeutic options are urgently needed for this difficult-to-treat patient population. PATIENT SUMMARY: We examined the efficacy and safety outcomes of treatments for non-muscle-invasive bladder cancer after bacillus Calmette-Guerin therapy. Outcomes varied across studies and patient populations, but emerging treatments currently in development show promising efficacy