Theoretical limits of the multistacked 1-D and 2-D microstructured inorganic solar cells

Recent studies in monocrystalline semiconductor solar cells are focused on mechanically stacking multiple cells from different materials to increase the power conversion efficiency. Although, the results show promising increase in the device performance, the cost remains as the main drawback. In this study, we calculated the theoretical limits of multistacked 1D and 2D microstructered inorganic monocrstalline solar cells. This system is studied for Si and Ge material pair. The results show promising improvements in the surface reflection due to enhanced light trapping caused by photon-microstructures interactions. The theoretical results are also supported with surface reflection and angular dependent power conversion efficiency measurements of 2D axial microwall solar cells. We address the challenge of cost reduction by proposing to use our recently reported mass-manufacturable fracture-transfer- printing method which enables the use of a monocrystalline substrate wafer for repeated fabrication of devices by consuming only few microns of materials in each layer of devices. We calculated thickness dependent power conversion efficiencies of multistacked Si/Ge microstructured solar cells and found the power conversion efficiency to saturate at %26 with a combined device thickness of 30 μm. Besides having benefits of fabricating low-cost, light weight, flexible, semi-transparent, and highly efficient devices, the proposed fabrication method is applicable for other III-V materials and compounds to further increase the power conversion efficiency above 35% range. © 2015 SPIE

Colossal Tunneling Electroresistance in Co-Planar Polymer Ferroelectric Tunnel Junctions

Ferroelectric tunnel junctions (FTJs) are ideal resistance-switching devices due to their deterministic behavior and operation at low voltages. However, FTJs have remained mostly as a scientific curiosity due to three critical issues: lack of rectification in their current-voltage characteristic, small tunneling electroresistance (TER) effect, and absence of a straightforward lithography-based device fabrication method that would allow for their mass production. Co-planar FTJs that are fabricated using wafer-scale adhesion lithography technique are demonstrated, and a bi-stable rectifying behavior with colossal TER approaching 106% at room temperature is exhibited. The FTJs are based on poly(vinylidenefluoride-co-trifluoroethylene) [P(VDF-TrFE)], and employ asymmetric co-planar metallic electrodes separated by &lt;20 nm. The tunneling nature of the charge transport is corroborated using Simmons direct tunneling model. The present work is the first demonstration of functional FTJs manufactured via a scalable lithography-based nano-patterning technique and could pave the way to new and exciting memory device concepts.</p

Metalized DNA Electrodes for Improved Hole Collection Efficiency in Polymer Heterojunction Solar Cells

Deoxyribonucleic acids (DNA) provide exciting opportunities as templates in self assembled architectures and functionality in terms of optical and electronic properties. In this study, we investigate the effects of DNA and metalized DNA sequences in polymer fullerene bulk-heterojunction (BHJ) solar cells. These effects are characterized via optical, quantum efficiency and current-voltage measurements. We demonstrate that by placing on the hole collection side of the active layer, DNA and Pt-DNA sequences lead to an increase in the power conversion efficiency (POE) by %16 and %30, respectively. Then, we examine the metallization process with SEM and AFM images and optimized the metallic cluster formation on DNA by changing the duration of steps in the process. Furthermore, we studied the electrical charge characteristics of our DNA layer by using capacitance voltage (C-V) measurements to explain the increase in hole collection. The shift in the C-V measurements showed that spray coated DNA formed a negatively charged layer which can increase the hole collection on the cathode side

Harnessing Knowledge on Very Important Pharmacogenes CYP2C9 and CYP2C19 Variation for Precision Medicine in Resource-Limited Global Conflict Zones

Ankarali, Handan Camdeviren/0000-0002-3613-0523;WOS: 000386220900007PubMed: 27726640Pharmacogenomics harnesses the utility of a patient's genome (n=1) in decisions on which therapeutic drugs and in what amounts should be administered. Often, patients with shared ancestry present with comparable genetic profiles that predict drug response. However, populations are not static, thus, often, population mobility through migration, especially enmasse as is seen for refugees, changes the pharmacogenetic profiles of resultant populations and therefore observed responses to commonly used therapeutic drugs. For example, in the aftermath of the Syrian civil war since 2011, millions have fled their homes to neighboring countries in the Middle East. The growing permanence of refugees and mass migrations is a call to shift our focus in the life sciences community from old models of pharmaceutical innovation. These seismic social changes demand faster decisions for population-to-population bridging, whereby novel drugs developed in or for particular regions/countries can meet with rational regulatory decisions/approval in world regions impacted by migrant/refugee populations whose profiles are dynamic, such as in the Eastern Mediterranean region at present. Thus, it is important to characterize and report on the prevalence of pharmacogenes that affect commonly used medications and predict if population changes may call for attention to particular differences that may impact health of patients. Thus, we report here on four single-nucleotide polymorphism (SNP) variations in CYP2C9 and CYP2C19 genes among Mersin-Turkish healthy volunteers in the Mersin Province in the Eastern Mediterranean region that is currently hosting a vast number of migrant populations from Syria. Both CYP2C9 and CYP2C19 are very important pharmacogene molecular targets. We compare and report here on the observed SNP genetic variation in our sample with data on 12 world populations from dbSNP and discuss the feasibility of forecasting the pharmacokinetics of drugs utilized by migrant communities in Mersin and the Eastern Mediterranean region. This study can serve as a catalyst to invest in research in Syrian populations currently living in the Eastern Mediterranean. The findings have salience for rapid and rational regulatory decision-making for worldwide precision medicine and, specifically, pharmacogenovigilance-guided bridging of pharmacokinetics across world populations in the current era of planetary scale migration

Label Free DNA Detection Using Large Area Graphene Based Field Effect Transistor Biosensors

We describe the fabrication of highly sensitive graphene based field effect transistor (FET) biosensors with a cost-effective approach and their application in label-free Deoxyribonucleic acid (DNA) detection. Chemical vapor deposition (CVD) grown graphene layers were used to achieve mass production of FET devices via conventional photolithographic patterning. Non-covalent functionalization of the graphene layer with 1-Pyrenebutanoic acid succinimidyl ester ensures high conductivity and sensitivity of the FET device. The present device could reach a detection limit as low as 3 X 10(-9) M

Temperature-induced lattice relaxation of perovskite crystal enhances optoelectronic properties and solar cell performance

Hybrid organic-inorganic perovskite crystals have recently become one of the most important classes of photoactive materials in the solar cell and optoelectronic communities. Albeit improvements focused on state-of-the-art technology including various fabrication methods, device architectures, and surface passivation, progress is yet to be made in understanding the actual operational temperature on the electronic properties and the device performances. The substantial effect of temperature on the optoelectronic properties, charge separation, charge recombination dynamics and photoconversion efficiency (PCE) are explored. The results clearly demonstrated a significant enhancement in the carrier mobility, photocurrent, charge carrier lifetime and solar cell performance in the 60±5 °C temperature range. In this temperature range, perovskite crystal exhibits a highly symmetrical relaxed cubic structure with well-aligned domains that are perpendicular to a principal axis, thereby remarkably improving the device operation. This finding provides a new key variable component and paves the way towards using perovskite crystals in highly efficient photovoltaic cells

Large-area plastic nanogap electronics enabled by adhesion lithography

Large-area manufacturing of flexible nanoscale electronics has long been sought by the printed electronics industry. However, the lack of a robust, reliable, high throughput and low-cost technique that is capable of delivering high-performance functional devices has hitherto hindered commercial exploitation. Herein we report on the extensive range of capabilities presented by adhesion lithography (a-Lith), an innovative patterning technique for the fabrication of coplanar nanogap electrodes with arbitrarily large aspect ratio. We use this technique to fabricate a plethora of nanoscale electronic devices based on symmetric and asymmetric coplanar electrodes separated by a nanogap < 15 nm. We show that functional devices including self-aligned-gate transistors, radio frequency diodes and rectifying circuits, multi-colour organic light-emitting nanodiodes and multilevel non-volatile memory devices, can be fabricated in a facile manner with minimum process complexity on a range of substrates. The compatibility of the formed nanogap electrodes with a wide range of solution processable semiconductors and substrate materials renders a-Lith highly attractive for the manufacturing of large-area nanoscale opto/electronics on arbitrary size and shape substrates

Printed memtransistor utilizing a hybrid perovskite/organic heterojunction channel

Neuromorphic computing has the potential to address the inherent limitations of conventional integrated circuit technology, ranging from perception, pattern recognition, to memory and decision-making (&nbsp;Acc. Chem. Res.&nbsp;2019,&nbsp;52&nbsp;(4), 964&minus;974) (&nbsp;Nature&nbsp;2004,&nbsp;431&nbsp;(7010), 796&minus;803) (&nbsp;Nat. Nanotechnol.&nbsp;2013,&nbsp;8&nbsp;(1), 13&minus;24). Despite their low power consumption (&nbsp;Nano Lett.&nbsp;2016,&nbsp;16&nbsp;(11), 6724&minus;6732), traditional two-terminal memristors can perform only a single function while lacking heterosynaptic plasticity (&nbsp;Nanotechnology&nbsp;2013,&nbsp;24&nbsp;(38), 382001). Inspired by the unconditioned reflex, multiterminal memristive transistors (memtransistor) were developed to realize complex functions, such as multiterminal modulation and heterosynaptic plasticity (&nbsp;Nature&nbsp;2018,&nbsp;554, (7693), 500&minus;504). Here we combine a hybrid metal halide perovskite with an organic conjugated polymer to form heterojunction transistors that are responsive to both electrical and optical stimuli. We show that the synergistic effects of photoinduced ion migration in the perovskite and electronic transport in the polymer layers can be exploited to realize memristive functions. The device combines reversible, nonvolatile conductance modulation with large switching current ratios, high endurance, and long retention times. Using in situ scanning Kelvin probe microscopy and variable-temperature charge transport measurement, we correlate the collective effects of bias-induced and photoinduced ion migration with the heterosynaptic behavior observed in this hybrid memtransistor. The hybrid heterojunction channel concept is expected to be applicable to other material combinations making it a promising platform for deployment in innovative neuromorphic devices of the future.</p

14 GHz schottky diodes using a p-doped organic polymer.

The low carrier mobility of organic semiconductors and the high parasitic resistance and capacitance often encountered in conventional organic Schottky diodes, hinder their deployment in emerging radio frequency (RF) electronics. Here we overcome these limitations by combining self-aligned asymmetric nanogap electrodes (∼25 nm) produced by adhesion-lithography, with a high mobility organic semiconductor and demonstrate RF Schottky diodes able to operate in the 5G frequency spectrum. We used C16 IDT-BT, as the high hole mobility polymer, and studied the impact of p-doping on the diode performance. Pristine C16 IDT-BT-based diodes exhibit maximum intrinsic and extrinsic cutoff frequencies (fC ) of >100 and 6 GHz, respectively. This extraordinary performance is attributed primarily to the planar nature of the nanogap channel and the diode's small junction capacitance (100 and ∼14 GHz respectively, while the DC output voltage of a RF rectifier circuit increases by a tenfold. Our work highlights the importance of the planar nanogap architecture and paves the way for the use of organic Schottky diodes in large-area radio frequency electronics of the future. This article is protected by copyright. All rights reserved