Enhanced performance of solution-processed carbon nanotube transparent electrodes in foldable perovskite solar cells through vertical separation of binders by using eco-friendly parylene substrate

The successful utilization of an eco-friendly and biocompatible parylene-C substrate for high-performance solution-processed double-walled carbon nanotube(CNT)electrode-based perovskite solar cells(PSCs)was demonstrated.Through the use of a novel inversion transfer technique,vertical separation of the binders from the CNTs was induced,rendering a stronger p-doping effect and thereby a higher conductivity of the CNTs.The resulting foldable devices exhibited a power conversion efficiency of 18.11%,which is the highest reported among CNT transparent electrode-based PSCs to date,and withstood more than 10,000 folding cycles at a radius of 0.5 mm,demonstrating unprecedented mechanical stability.Furthermore,solar modules were fabricated using entirely laser scribing processes to assess the potential of the solution-processable nanocarbon electrode.Notably,this is the only one to be processed entirely by the laser scribing process and to be biocompatible as well as eco-friendly among the previously reported nonindium tin oxide-based perovskite solar modules.

Moth-eye Structured Polydimethylsiloxane Films for High-Efficiency Perovskite Solar Cells

Large-area polydimethylsiloxane(PDMS)films with variably sized moth-eye structures were fabricated to improve the efficiency of perovskite solar cells.An approach that incorporated photolithography,bilayer PDMS deposition and replication was used in the fabrication process.By simply attaching the moth-eye PDMS films to the transparent substrates of perovskite solar cells,the optical properties of the devices could be tuned by changing the size of the moth-eye structures.The device with 300-nm moth-eye PDMS films greatly enhanced power conversion efficiency of ~21 % due to the antireflective effect of the moth-eye structure.Furthermore,beautiful coloration was observed on the 1000-nm moth-eye PDMS films through optical interference caused by the diffraction grating effect.Our results imply that moth-eye PDMS films can greatly enhance the efficiency of perovskite solar cells and building-integrated photovoltaics.

Dual function of a high-contrast hydrophobic-hydrophilic coating for enhanced stability of perovskite solar cells in extremely humid environments

In spite of a continuous increase in their power conversion efficiency （PCE） and an economically viable fabrication process,organic-inorganic perovskite solar cells （PSCs） pose a significant problem when used in practical applications：They show fast degradation of the PCE when exposed to very humid environments.In this study,the stability of PSCs under very humid conditions is greatly enhanced by coating the surface of the PSC devices with a multi-layer film consisting of ultrahydrophobic and relatively hydrophilic layers.A hydrophobic composite of poly（methyl methacrylate） （PMMA）,polyurethane （PU）,and SiO2 nanoparticles successfully retards the water molecules from very humid surroundings.Also,the hydrophilic layer with moderately PMMA captures the residual moisture within the perovskite layer;subsequently,the perovskite layer recovers.This dual function of the coating film keeps the PCE of PSCs at 17.3% for 180 min when exposed to over 95% humidity.

Assembly of charged aerosols on non-conducting substrates via ion-assisted aerosol lithography （IAAL）

The development of ion-assisted aerosol lithography （IAAL） has enabled fabrication of complex three- dimensional nanoparticle （NP） structures on conducting substrates. In this work, the applicability of the IAAL technique was investigated on non-conducting substrates. The NP structure growth process on a non-conducting substrate was found to self-terminate and the structures subsequently repel incoming charged NPs and scatter them away. Electric field calculations supported the experimental findings and confirmed that the electric field distortions owing to charge build-up within the structures prevented additional NP deposition thereon. To regulate the charge build-up without compromising the number of NPs available for assembly, a corona discharger and an ion trap were implemented. By varying the number of ions available in the assembly process, an optimum level of ion injection was found that allowed for a prolonged （〉120 rain） assembly of NP structures on non-conducting substrates without the unwanted scattering of NPs.

3D Nanoprinting with Charged Aerosol Particles-An Overview

CONSPECTUS:Three-dimensional(3D)printing is a revolutionary technology allowing rapid,cost-effectively,and flexible design of desired 3D products.In this regard,various techniques for downscaling 3D printing have been developed based on several methodologies in the past decades to exploit the advantages of 3D printing at the micro/nanoscale.The development of 3D nanoprinting techniques has provided a method to design unique and sophisticated nanoscale 3D objects enabling functional applications that are thus far constrained with conventional planar nanomanufacturing processes such as photolithography and electron beam lithography.However,the versatile and practical realization of 3D nanoprinting in a broad science and engineering field remains challenging due to limitations such as feature size resolution,suitable materials,and design flexibility.Therefore,innovative 3D nanoprinting techniques are required to overcome current limitations.In this Account,we describe our achievements in developing 3D nanoprinting with charged aerosols relying on the physics behind counteracting electric fields.We introduce the generation of charged aerosols,the most feasible in the broad range of fundamental building blocks(mainly all types of metals and alloys,their oxides,polymers,and organics)for 3D nanoprinting.Moreover,charged aerosols can be processed at ambient conditions easily.The aerosols could be precisely controlled and delivered for the assembly,using electric fields of complicated configurations despite the Brownian diffusion and other chaotic processes.The converging electric fields are formed around openings by the interactions of two electric fields.One of the electric fields comes from a negatively biased substrate.In contrast,the counteracting electric field comes from the positive ions distributed on a prepatterned dielectric layer over the substrate.As a result,the positively charged aerosols are focused through these fields to grow with nanoscale resolution only in the openings of the layer.Furthermore,a growing structure itself could reconfigure the electric field,producing self-focusing nonlinear effects shaping the printed structure.By lifting the layer over the substrate and translating the latter according to a 3D motion program,we created charged aerosol jets that self-focus on the tips of the growing structure and could print diverse 3D forms.The aerosol jets are also capable of writing on the substrate.The 3D nanoprinting produced using the described approach enables the development of the intricate 3D nanostructures described in the Account in detail,including their material characterization and diverse applications.Finally,we concluded and outlined current challenges and future developments of the 3D nanoprinting with charged aerosol particles.