The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

American Society for Testing and Materials

Since the report in 2012 of a solid-state perovskite solar cell (PSC) with a power-conversion efficiency (PCE) of 9.7% and a stability of 500 h, intensive efforts have been made to increase the certified PCE, reaching 25.2% in 2019. The PCE of PSCs now exceeds that of conventional thin-film solar-cell technologies, and the rate at which this increase has been achieved is unprecedented in the history of photovoltaics. Moreover, the development of moisture-stable and heat-stable materials has increased the stability of PSCs. Small-area devices ( 100 cm2) substrates required for commercialization. Thus, materials and methods need to be developed for coating large-area PSCs. In this Review, we discuss solution-based and vapour-phase coating methods for the fabrication of large-area perovskite films, examine the progress in performance and the parameters affecting the properties of large-area coatings, and provide an overview of the methodologies for achieving high-efficiency perovskite solar modules. The scalable fabrication of perovskite solar cells and solar modules requires the development of new materials and coating methods. In this Review, we discuss solution-based and vapour-phase coating methods for large-area perovskite films and examine the progress in performance and the parameters affecting large-area coatings.

Scalable fabrication and coating methods for perovskite solar cells and solar modules

Solution-processed organic light-emitting diodes (s-OLEDs) have received a great deal of interest owing to the huge market application potentials as large-size, flexible, high-quality self-luminous display panels and lighting sources. It is anticipated that those electronic products can be easily manufactured by modern wet-processing techniques, e.g. ink-jet printing and ‘roll-to-roll’ coating methods. However, issues related to power efficiency (PE) are highly hampering the progress of s-OLEDs towards real applications. Herein, we will demonstrate current development of s-OLEDs targeting for high PE with emphasis on introducing (i) theoretical and practical significance in simultaneously achieving close-to-unity (∼100 %) exciton emission and low driving voltage realized by advanced interface modification, bipolar-transporting-type host, all-exciton-harvesting emissive material and customized device architectures to integrate their functions, (ii) novel low-driving-voltage techniques for phosphorescent and thermally activated delayed fluorescence (TADF) s-OLEDs, i.e. barrier-free exciplex host or bipolar co-host scaffold, and charge-trapping- or charge-scattering-free emissive layer (EML) structures by matching the frontier molecular orbitals (FMOs) between host and dopant emitters, (iii) a variety of tactics to effectively alleviate the efficiency roll-off issue at the practically high luminance value, e.g. removing or largely restraining exciton-quenching in the EML and/or interfaces, the utilization of novel emitters with fast radiative decay rate and/or the EML architectures with prompt and efficient Forster energy transfer process.

Towards high-power-efficiency solution-processed OLEDs: Material and device perspectives

Flexible and sensitive sensors that can detect external stimuli such as pressure, temperature, and strain are essential components for applications in health diagnosis and artificial intelligence. Multifunctional sensors with the capabilities of sensing pressure and temperature simultaneously are highly desirable for health monitoring. Here, we have successfully fabricated a flexible and simply structured bimodal sensor based on metal–organic frameworks (MOFs) derived porous carbon (PC) and polydimethylsiloxane (PDMS) composite. Attributed to the porous structure of PC/PDMS composite, the fabricated sensor exhibits high sensitivity (15.63 kPa–1), fast response time ( 0.11 °C–1) and fast response time (∼100 ms), indicating its p...

Multifunctional Sensor Based on Porous Carbon Derived from Metal-Organic Frameworks for Real Time Health Monitoring.

An effective combination reaction involved with sputtered and selenized Sb precursors for efficient Sb2Se3 thin film solar cells

Effects of Sr addition on microstructure, mechanical and corrosion properties of biodegradable Mg–Zn–Ca alloy

The rational design of high-performance flexible pressure sensors with both high sensitivity and wide linear range attracts great attention because of their potential applications in wearable electronics and human-machine interfaces. Here, polyaniline nanofiber wrapped nonwoven fabric was used as the active material to construct high performance, flexible, all fabric pressure sensors with a bottom interdigitated textile electrode. Due to the unique hierarchical structures, large surface roughness of the polyaniline coated fabric and high conductivity of the interdigitated textile electrodes, the obtained pressure sensor shows superior performance, including ultrahigh sensitivity of 46.48 kPa−1 in a wide linear range (<4.5 kPa), rapid response/relaxation time (7/16 ms) and low detection limit (0.46 Pa). Based on these merits, the practical applications in monitoring human physiological signals and detecting spatial distribution of subtle pressure are demonstrated, showing its potential for health monitoring as wearable electronics.

https://www.mdpi.com/2073-4360/11/7/1120/pdf

Polyaniline Nanofiber Wrapped Fabric for High Performance Flexible Pressure Sensors

Air-Stable Solar Cells with 0.7 V Open-Circuit Voltage Using Selenized Antimony Sulfide Absorbers Prepared by Hydrazine-Free Solution Method

Thermally activated delayed fluorescence (TADF) emitters have received much attention for the fabrication of white organic light-emitting diodes (WOLEDs); however, challenges remain owing to severe efficiency roll-off, poor color stability, and high cost. In this contribution, solution-processed hybrid WOLEDs were obtained by employing a blue TADF dendrimer, bis{4-[3,6-bis(3,6-di-tert-butylcarbazol-N-yl)carbazol-N-yl]phenyl}sulfone (BPS), combined with an orange iridium complex, bis(2-phenylbenzothiazolato)(acetylacetonate)iridium(III), Ir(bt)2 (acac), as a co-dopant. The devices achieved a maximum external quantum efficiency of 6.59 % and a maximum current efficiency of 17.34 cd A-1 . The results suggest that the TADF dendrimer serving as an assistant dopant were helpful in reducing the triplet populations by up-converting the triplet excitons to the singlet state and immediately transferring the singlet excitons to Ir(bt)2 (acac) (bt=2-phenylbenzothiazolato, acac=acetylacetonato) by virtue of the long-range Forster resonance energy transfer, thus significantly decreasing the triplet-triplet annihilation (TTA). Moreover, the emitters can act as shallow trapping centers to decrease charge and exciton aggregation. The resulting OLEDs exhibit stable electroluminescent spectra and low efficiency roll-off at relatively high current density. The CIE coordinates Δ(x, y) vary only (0.02, 0.02) in the luminance range of 100 to 10 000 cd m-2 .

Xiang Meng

Papers

Effects of Sr addition on microstructure, mechanical and corrosion properties of biodegradable Mg–Zn–Ca alloy

Polyaniline Nanofiber Wrapped Fabric for High Performance Flexible Pressure Sensors

Air-Stable Solar Cells with 0.7 V Open-Circuit Voltage Using Selenized Antimony Sulfide Absorbers Prepared by Hydrazine-Free Solution Method

Solution-Processed Warm White Organic Light-Emitting Diodes Based on a Blue Thermally Activated Delayed Fluorescence Dendrimer.

Novel n-type thermoelectric material of ZnIn2Se4