The fabrication of homogeneous perovskite films on non-wetting interfaces enabled by physical modification

Conjugated polymers are commonly used as effective hole transport materials(HTMs) for preparation of high-performance perovskite solar cells. However, the hydrophobic nature of these materials renders it difficult to deposit photovoltaic perovskite layers on top via solution processing. In this article, we report a generic surface modification strategy that enables the deposition of uniform and dense perovskite films on top of non-wetting interfaces. In contrast to the previous proposed chemical modifications which might alter the optoelectronic properties of the interfacial layers, we realized a nondestructive surface modification enabled by introducing a layer of insulating mesoporous aluminum oxide(Al2O3). The surface energies of the typical non-wetting hole-transport layers(PTAA, P3 HT, and Poly-TPD) were significantly reduced by the Al2O3 modification. Benefiting from the intact optoelectronic properties of the HTMs, perovskite solar cells deposited on these interface materials show full open-circuit voltages( V OC) with high fill factors(FF) up to 80%. Our method provides an effective avenue for exploiting the full potential of the existing as well as newly developed non-wetting interface materials for the fabrication of high-performance inverted perovskite solar cells.

Non-wetting Additive as a Solution to Minimize the Corrosion of Refractory Castables Against Molten Aluminum

The ternary compound barium aluminosilicate BaAl2Si2O8, known as celsian, a non-wetting additive that increases the corrosion resistance of refractor） materials against molten aluminum, was incorporated into the matrix of a high-alumina low cement castable after its synthesis using barite and a low cost source of alumina and silica. This paper presents the influence of this phase on the wetting angle formed between liquid aluminum alloy and solid refractory castable surface.

A non-wetting and conductive polyethylene dioxothiophene hole transport layer for scalable and flexible perovskite solar cells

The regulated crystallization of perovskite and highly repeatable preparation are decisive challenges for large-scale flexible perovskite solar cells(PSCs).Herein,we synthesize an oil-soluble poly(3,4-ethylenedioxythiophene)(Oil-PEDOT)as a hole transport layer(HTL).The non-wetting Oil-PEDOT HTL can promote the quality of large-area flexible perovskite films because of its optimized crystallinity and printability.The Oil-PEDOT layer also delivers desirable conductivity and charge transport without a complex doping.Consequently,the flexible PSCs with Oil-PEDOT HTL achieve an efficiency of 19.51%and 16.70%based on 1.05 and 22.50 cm^(2),respectively.Moreover,these large-scale flexible PSCs demonstrate remarkable mechanical robustness,and the efficiency exhibits 93%retention after 7,000 bending cycles.These results show that the Oil-PEDOT is a potentially efficient HTL for fabricating efficient large-scale flexible PSCs.

Failure mechanisms and assembly-process-based solution of FCBGA high lead C4 bump non-wetting

This paper studies the typical failure modes and failure mechanisms of non-wetting in an FCBGA（flip chip ball grid array） assembly.We have identified that the residual lead and tin oxide layer on the surface of the die bumps as the primary contributor to non-wetting between die bumps and substrate bumps during the chipattach reflow process.Experiments with bump reflow parameters revealed that an optimized reflow dwell time and H_2 flow rate in the reflow oven can significantly reduce the amount of lead and tin oxides on the surface of the die bumps,thereby reducing the non-wetting failure rate by about 90%.Both failure analysis results and mass production data validate the non-wetting failure mechanisms identified by this study.As a result of the reflow process optimization,the failure rate associated with non-wetting is significantly reduced,which further saves manufacturing cost and increases capacity utilization.

Tailored PEDOT:PSS hole transport layer for higher performance in perovskite solar cells: Enhancement of electrical and optical properties with improved morphology

Precise control over the charge carrier dynamics throughout the device can result in outstanding performance of perovskite solar cells(PSCs).Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)is the most actively studied hole transport material in p-i-n structured PSCs.However,charge transport in the PEDOT:PSS is limited and inefficient because of its low conductivity with the presence of the weak ionic conductor PSS.In addition,morphology of the underlying PEDOT:PSS layer in PSCs plays a crucial role in determining the optoelectronic quality of the active perovskite absorber layer.This work is focused on realization of a non-wetting conductive surface of hole transport layer suitable for the growth of larger perovskite crystalline domains.This is accomplished by employing a facile solventengineered(ethylene glycol and methanol)approach resulting in removal of the predominant PSS in PEDOT:PSS.The consequence of acquiring larger perovskite crystalline domains was observed in the charge carrier dynamics studies,with the achievement of higher charge carrier lifetime,lower charge transport time and lower transfer impedance in the solvent-engineered PEDOT:PSS-based PSCs.Use of this solventengineered treatment for the fabrication of MAPbI3 PSCs greatly increased the device stability witnessing a power conversion efficiency of 18.18%,which corresponds to^37%improvement compared to the untreated PEDOT:PSS based devices.

A sponge-based iron-tannic-acid hydrogel interface evaporator designed for clean water production

Due to the rapid advancement of technologies,there has been a significant increase in the discharge of industrial wastewater,and freshwater is becoming a scarce resource.Currently,research on solar evaporators is mainly focused on the efficient production of clean water,with less emphasis on the removal of residual pollutants remaining in the original solutions.Through this study,problems,including the difficult recovery of catalyst powder and the difficult removal of floating organic matter are solved by co-depositing low-surface-tension zirconia particles and bismuth tungstate onto the floating layer.Hydrogels and melamine sponges were combined to solve the problem that traditional hydrogels lack mechanical strength.An excellent water-repellent effect can be seen from the contact angle between the liquid globule and canvas/felt,which is greater than 155°.The steam generation rate of the assembled evaporation system is 1.78 kg m^(-2)h^(-1),and its purification efficiency for methyl orange and rhodamine B exceeds 99%.This study presents a novel strategy for treating wastewater contaminated with organic dyes,aiming to solve problems including environmental damage,water pollution,and water scarcity.

Fabrication of Self-cleaning Antireflective Polymer Surfaces by Mimicking Underside Leaf Hierarchical Surface Structures

In this work, we utilized underside of four different plant leaves with different scale of hierarchical surface roughness to fabricate large area self-cleaning antireflective polymer surfaces. A simple and precise two-step soft-lithography replica molding technique was deployed by using polydimethylsiloxane (PDMS) polymer as a replicating material. In the first step, a negative PDMS replica was fabricated by using the underside of an original leaf as a template material. In the second step, a positive PDMS replica was fabricated through a negative PDMS replica used as a template. In order to study the non-wetting and light trapping properties, as-replicated polymer surfaces were characterized using Scanning Electron Microscopy (SEM), contact angle goniometer, and UV-Vis spectroscopy. SEM images confirmed the successful replication of complex hierarchical structures while contact angle measurement studies established retaining high non-wetting properties in polymer replicas. Optical studies suggest near zero reflection in normal mode and less than 5% diffuse reflection when measured using integrated sphere mode. These results have been correlated and explained with the air-liquid fraction and roughness factor as measured using three-dimensional optical profilometer.