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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.

MATERIALS FOR HUMANITY (MH 21)

Effect of Perovskite Thickness on Electroluminescence and Solar Cell Conversion Efficiency

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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.

Super-Hygroscopic Film Based Wearables for Expediting Sweat Evaporation and Energy Harvesting

Polylactic acid (PLA) mixed with long-persistent phosphor (Ca2BO3Cl: Eu2+, Dy3+) was prepared in this study. The sustainable yellow luminescence of the composites could be clearly observed. The mechanical properties of the composite filaments were tested, including maximal force and elasticity modulus. In particular, the influence of humidity on mechanical properties was studied and optimal mixing conditions were found. Finally, the prepared composite filaments were printed into a hollow dodecahedron and presented in this study.

PLA/Ca2BO3Cl: Eu2+, Dy3+, A Novel Sustainable Luminescence Composite Material for 3D Printing

Microporous structure plays a significant role in bone tissue engineering, to influence inductive bone formation and elevate bone ingrowth inside microporous scaffolds. We hereby fabricated microporous scaffolds by 3D printing with mixture of porogens and photopolymerizing resin. We tuned the microporosity of scaffolds from 0% to 36% by varying the porogen concentration in the inks from zero to 60 vol%. The microporosity and microspore size of scaffolds can affect in vitro expansion of preosteoblast cells. Our studies revealed that preosteoblast cells’ in vitro adhesion and proliferation were significantly mediated by the printed scaffolds. Cells proliferation on scaffolds with 20-30% microporosity showed much higher rate than on other scaffolds. In this microporosity range, scaffolds also showed much better cell spreading and morphologies. At a low level of microporosity (<7%), the cell proliferation rate was even lower than the solid scaffolds, which indicates that the microporous structure is “toxic” for cells at low microporosity range. A higher microporosity (> 35%) led to very poor cell attachment and is unfavorable for the proliferation of MC3T3-E1 cells. Furthermore, the printed dual macro-/micro-porous scaffolds showed higher proliferation rate of MC3T3-E1 cells as compared to mono-pore sized scaffolds, either the macro-porous or microporous structure.

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Effect of Perovskite Thickness on Electroluminescence and Solar Cell Conversion Efficiency

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