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Silver bismuth iodide has been studied comprehensively for its potential as light harvesters, owing to their low toxicity and environment conviviality. However, they often suffer with low efficiencies as compared to conventional light harvesters and hence there is a broad room for improvement. Here we propose doping the standard AgBiI4 composition with tin (Sn), to improve the relative absorbance and thereby potentially improving the efficiencies. It is observed that the addition of Sn did not alter the structural properties significantly, while it works on the orientation of the crystal growth during thin film synthesis, leading to ordered and uniform films. An improvement in absorption coefficient was observed, which can be considered to improve the performances of devices fabricated with AgBiI4 as light harvesters.

MATERIALS FOR HUMANITY (MH 21)

Tin Doped Silver Bismuth Iodide as Superior Energy Harvesters

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All solution-processed semi-transparent perovskite solar cells (PSCs) with high efficiency were fabricated with Ag nanowire (AgNW) top electrode directly coated on the organic electron transport layer (ETL). A unique AgNW/ETL interface morphology was attained by the fabrication of a AgNW-C60 composite electrode through a sequential spin-coating method, resulting in a translucent PSC with PCE of 11.02% and remarkable stability improvement. The low-temperature solution-processed and semitransparent AgNW-C60 top electrode is also applicable to other PSC structures with various interfacial layers, thus showing a promising path towards fully-printable, flexible and translucent photovoltaic devices.

Ag-nanowires/C60 composite electrode for translucent perovskite solar cells

Mixed organic-inorganic halide perovskite solar cell’s (PSC) are an emerging photovoltaic technology that has the promise of significantly lower production costs coupled with the high absorption coefficient, tunable bandgap and long carrier lifetime. It also shows promising capability as semitransparent solar cell amid its strong absorption in very thin thickness. However, to maintain the morphology quality and maximize the solar cell performance, increasing the light absorbance is a necessity. Herein we study the effect of Au nanoparticles as plasmonic layers between the PSC and its transport layers in order to improve the light-harvesting capability through localized surface plasmon resonance (LSPR). varying thickness of the Au film were conducted through physical vapor deposition (PVD) and annealing under different temperatures to achieve thermal dewaetting of the Au film for the formation of separated Au nano islands. The photovoltaic performance of the fabricated cells was then evaluated and studied through morphology, crystallographic and optical correlations. Several architectures were studied, such as in between PSC and ETL as well as PSC and HTL. Although results demonstrated an overall decrease in the PCE as compared to the control, we elucidate the necessity of a capping layer surrounding the Au NPs in order to minimize surface recombination of the photo-generated excitons due to the formation of metal-semiconductor Schottky barriers. We found that the PSCs showed an improvement from an average PCE of 4.57% to 5.66% when an additional SnO2 layer was spin-coated between the Au and Cs0:05(MA0:17FA0:83)0:95Pb(I0:83Br0:17)3 layer. PCE of the best performing plasmonic-based device in this study was 11.54% by depositing Au between the TiO2 layers of the PSC. Further optimization in the capping structure, shape and the amount of Au as well as spacing between the Au can be performed to achieve the enhancement from the plasmon effect.

Thermal dewetting of Au film in between perovskite and its transport layers

A hybrid organic–inorganic perovskite in a diode structure can lead to multifunctional device phenomena exhibiting both a high-power conversion efficiency (PCE) of a solar cell and strong electroluminescence (EL) efficiency. Non radiative losses in such multifunctional devices lead to open circuit voltage (Voc) deficit which is a limiting factor to push the efficiency towards Shockley–Queisser (SQ) limit. In this work we analyse and quantify the radiative limit of Voc in perovskite solar cell as a function of its absorber thickness. We correlate PCE and EL efficiency at varying thicknesses to understand the limiting factors for high Voc. With certain increase in perovskite thickness, PCE improves but EL efficiency is compromised and, vice versa. Thus, correlating these two figures of merits of a solar cell guides towards light management strategy together with minimizing non-radiative losses. The results demonstrate that maximizing absorption and emission processes remains paramount for optimizing devices.

Effect of Perovskite Thickness on Electroluminescence and Solar Cell Conversion Efficiency

Our current work examines various solution-processed ternary zinc-tin oxide (ZTO) compositions as plausible compact ETL candidates in the fully planar perovskite configuration. Systematically optimized ETLs verified the superiority of ZTO ETL based devices compared to the devices made with pristine ZnO ETL. Furthermore, the use of SnO2 interlayer between the ZTO and perovskite to form a bilayer ETL structure enhanced the device performance significantly. Apart from prohibiting the unfavorable contact between the ZnO film with the perovskite layer, the bilayer ETL structure showed further improvement in reproducibility, charge transport, recombination resistance, device stability, and efficiency. Paramount PCE of 19.01 %, with an average PCE of 18.18 %, was demonstrated in the Zn1 Sn1O/SnO2 ETL based devices. In addition, exceptional stability was obtained in which 90% of its initial PCE was maintained after 90 days without encapsulation. The superior performance and device stability are attributed to the improved charge extraction, favourable energy alignment, and suppressed charge recombination derived from the compatible Zn1 Sn1O/SnO2 bilayer ETL. Our work highlighted the viability of ternary metal oxides as highly effective and reproducible ETL candidates for planar perovskite solar cell application. We also demonstrated the importance of a compatible SnO2 interlayer between the ternary metal/perovskite interface whereby nonpareil PCE and profound improvement in device stability were manifested.

Solution processed ternary metal oxide electron transport layers for highly efficient perovskite solar cells

CuSCN as hole transport layer can enhance the hole extraction ability and improve the performance of carbon-electrode devices. However, the interfacial degradation of the perovskite/CuSCN contact restricts its application. Our further studies indicated that the diffusion of SCN- into the perovskite film would produce more interfacial defects and aggravate nonradiative recombination at a certain temperature, thus hindering the carrier transport. The reasons for performance attenuation during the thermal treatment of carbon electrodes were further disclosed by the ultraviolet photoelectron spectroscopy and a vacuum-assisted drying process for carbon electrodes was proposed to suppress the destructive effect. Finally, an enhanced efficiency of 15.72% was achieved for perovskite solar cells with a CuSCN inorganic HTL and screen-printable carbon electrode.

The effect of thermal treatment temperature for carbon electrodes on the performance of perovskite solar cells with CuSCN hole transport layer

Surface imperfections are detrimental roots to various defect sites in halide perovskites (HPs) films affecting device performance and stability. To mitigate such fabrication defects, we introduced a new class of all-organic surface modifiers consisting of alkylammonium and alkanoate ions on the surface of HP layer passivating interfacial defects and improve moisture tolerance. Compared to iodidebased salts, these robust carboxylate anions display higher resistant towards oxidation and superior stability across different organic solvents. Resultant perovskites with traceless low dimensional structure demonstrate remarkable device performance with power conversion efficiency (PCE) more than 18.5% and enhanced operational stability retaining 85% initial PCE in ambient over 1500 hours.

Effects of All‐Organic Interlayer Surface Modifiers on the Efficiency and Stability of Perovskite Solar Cells

Introduction - Phase Change Materials (PCMs) 1) Promising thermal energy storage (TES) materials. - High heat capacity. - Narrow operating temperature range. 2) Wide range of applications - Eg: energy efficient buildings, food packaging, and solar panels. 3) Organic PCMs (oPCMs) are most commonly used.2 - Eg: paraffins, fatty acids, alcohols, or esters. - Stable, no phase separation, little super-cooling. 4) Key problem: High Flammability of oPCMs.

Phase Change Materials with lowered flammability

ABSTRACT Since 2003 the European Union has accelerated the immediate replacement of hazardous materials from consumer products, especially lead and lead-based systems from electrical and electronic equipment, by lead-free systems. However, inspite of significant research across the globe a suitable alternative to potential lead based system PZT has not been identified. Barium Calcium Zirconium Titanate (Ba0.89 Ca0.11 Zr0.10 Ti0.90) O3,is a promising lead free system which exhibit functional response at par or better than the prominent lead based systems like PZT or PMN-PT. In this report we will present our study primarily focussed on realization of BCZT ceramic by using sintering aid, which could bring down sintering temperature below 1400 oC, so that firing of the ceramic could be carried out at ordinary lab furnace. Structural and microstructural features of the synthesized ceramic BCZT – xPr (x = 0.00, 0.02,0.04, and 0.06) along with functional attributes will be analyzed in the presentation. Various steps taken to realize quality ceramic will be illustrated. The average piezoelectric constant d33 was obtained in the range of 144 – 150 pC/N and was lower than expected value. The dielectric maxima were observed near the Curie point as expected. Well defined slim ferroelectric hysteresis loop of BCZT – (x)Pr prepared with varying Pr6O11concentration indicates, the capability and stability of the ceramics at high voltage (3900 V) and frequency (50 Hz).The doped ceramic were found to be stable even at high voltage and high frequency and hence will be useful for diverse applications.

REALIZATION OF LOW TEMPERATURE SINTERED BCZT CERAMIC, THROUGH Pr DOPING AND RUDIMENTARY ANALYSIS

Continuous fiber reinforced thermoplastic polymer composites (CFRTP) are becoming more significant in industrial applications because of their unique advantages such as excellent mechanical and chemical performance, light weight, short molding cycle, secondary molding and waste recycling. However, the difficulty in developing CFRTP is how to combine fiber with thermoplastics due to the significant difference in surface property between fiber and thermoplastic matrix. In this work, we presented the method to create the strong interaction between polymer matrix and fiber to improve the interface adhesion. The result from this study indicates that the strength of the CFRTP increase both along and cross fiber direction by introducing the interface interaction. The breaking behavior of the CFRTP suggests the different breaking mechanism of the CFRTP. This method is also applicable for production scale as the interaction was created within second time scale.

Composite resin to enhance interface between matrix and fiber in continuous fiber reinforced thermoplastic composites

Absorbing the moisture from sweat evaporation would prevent the accumulation of sweat, and thus inhibit the growth of bacteria or fungi, providing a healthy and comfortable microclimate for people. However, there have been almost no such attempts. On the other hand, sweat has always been considered a waste resource and attempts to tap this free resource in the form of energy are relatively sparse. To realize these ideas, here we developed a cobalt-complex based super-hygroscopic material (Co-SHM). Integrating the Co-SHM into breathable and waterproof PTFE membranes, we designed new kinds of armpit pad, shoe lining, and insole, which can rapidly absorb the moisture from sweat evaporation to prevent sweat accumulation. The absorbed sweat can be transduced to energy through a Co-SHM based wearable energy harvesting device that consists of an eight-series-connection of electrochemical cells.

Next from MATERIALS FOR HUMANITY (MH 21)

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