Perovskite solar cells (PSCs) have emerged as promising candidates for photovoltaic applications because of their superior optoelectronic properties. The power conversion efficiency of 25.5% has been achieved at an astonishing speed from the debut of 3.8%. However, the notoriously poor stability stemming from the solution fabrication process and uncontrollable rapid crystallization limits the commercialization of PSCs. Thus defects are inevitable among the bulk films and interfaces. Herein, recent progress about defects passivation by additive strategy among the bulk film, are discussed. More importantly, the defects passivation strategy for perovskite/electron transport layer and perovskite/hole transport layer interfaces are summarized. Furthermore, how defects passivation and ion migration would affect the stability performance of the perovskite devices are elaborated. Finally, the current challenges for commercialization prospects of perovskite photovoltaic applications are discussed.
The high interest in organic light-emitting device (OLED) technology is largely due to their flexibility. Up to now, indium tin oxide (ITO) films have been widely used as transparent conductive electrodes (TCE) in organic opto-electronic devices. However, ITO films, typically deposited on glass are brittle and they make it difficult to produce flexible devices, restricting their use for flexible devices. In this study, we report on a nano-composite TCE, which is made of a silver nanowire (AgNW) network, combined with aluminum-doped zinc oxide (ZnO:Al, AZO) by atomic layer deposition. The AgNWs/AZO composite electrode on photopolymer substrate shows a low sheet resistance of only 8.6 Ω/sq and a high optical transmittance of about 83% at 550 nm. These values are even comparable to conventional ITO on glass. In addition, the electrodes also have a very smooth surface (0.31 nm root-mean-square roughness), which is flat enough to contact the OLED stack. Flexible OLED were built with AgNWs/AZO electrodes, which suggests that this approach can replace conventional ITO TCEs in organic electronic devices in the future.
The generation of droplets is one of the most critical steps in the ddPCR procedure. In this study, the mechanism of droplet formation in microchannel structure and factors affecting droplet formation were studied. The physical field of laminar two-phase flow level was used to simulate the process of droplet generation through microfluidic technology. The effect of the parameters including flow rate, surface tension, and viscosity on the generated droplet size were evaluated by the simulation. After that, the microfluidic chip that has the same dimension as the simulation was then, fabricated and evaluated. The chip was made by conventional SU-8 photolithography and injection molding. The accuracy of the simulation was validated by comparing the generated droplets in the real scenario with the simulation result. The relative error (RE) between droplet diameter and flow rate ratio of the two fluids was found less than 3.5%. Besides, the coefficient of variation (CV) of the droplet diameter was less than 1%, which indicates the experimental droplet generation was of high stability and reliability. This study provides not only fundamental information for the design and experiment of droplet generation by microfluidic technology but also a reliable and efficient investigation method in the ddPCR field.
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