Recent progress of hybrid cathode interface layer for organic solar cells

Organic solar cells(OSCs)have gained conspicuous progress during the past few decades due to the development of materials and upgrading of the device structure.The power conversion efficiency(PCE)of the single-junction device had surpassed 19%.The cathode interface layer(CIL),by optimizing the connection between the active layer and the cathode electrode,has become a momentous part to strengthen the performances of the OSCs.Simultaneously,CIL is also indispensable to illustrating the working mechanism of OSCs and enhancing the stability of the OSCs.In this essay,hybrid CILs in OSCs have been summarized.Firstly,the advancement and operating mechanism of OSCs,and the effects and relevant design rules of CIL are briefly concluded;secondly,the significant influence of CIL on enhancing the stability and PCE of OSCs is presented;thirdly,the characteristics of organic hybrid CIL and organic-inorganic hybrid CIL are introduced.Finally,the conclusion and outlook of CIL are summarized.

Photoelectrochemical Studies at CdS/PTTh Nanoparticles Interfaces

Photo-activities at Inorganic/Organic/Interfaces (IOI) consisting of CdS/ Polyterthiophine (PTTh) assemblies were investigated in nanoparticle suspension and in thin solid film forms. The effects PTTh modifier cause on the photoelec-trochemical behavior of the IOI were investigated using [Fe(CN)6]4- as photoactive hydrated electron donor agent. Results show that the adsorption process of [Fe(CN)6]3- (photolysis product) control the photoactivity outcome of IOI assemblies. CdS/PTTh shows lower heterogeneous photochemical response than native CdS. Native CdS amorphous nanoparticles adsorb more [Fe(CN)6]3- with very steady adsorption /desorption process than the modified ones. The interface activities were explained by analyzing the IOI junctions’ characteristics, such as electron affinity, work function and hole/electrons barrier heights. The aqueous nano-systems retained moderate stability as indicated by the reproducibility of their photocatalytic activities. Both [Fe(CN)6]4- and PTTh contributed to the stability of native CdS surfaces.

MINERAL BRIDGES OF NACRE AND ITS EFFECTS

Nacre, or mother-of-pearl, is a kind of composites of aragonite platelets sandwiched between organic materials. Its excellent mechanical properties are thought to stem from the micro architecture that is traditionally described as a 'brick and mortar' arrangement. In this paper, a new microstructure, referred to as mineral bridge in the biomineralization, is directly observed in the organic matrix layers (mortar) of nacre. This is an indication that the organic matrix layer of nacre should be treated as a three-dimensional interface and the micro architecture of nacre ought to be considered as a 'brick-bridge-mortar' structure rather than the traditional one. Experiments and analyses show that the mineral bridges not only improve the mechanical properties of the organic matrix layers but also play an important role in the pattern of the crack extension in nacre.

Organic interfacial engineering of gold nanowires for selective glycerol electrooxidation

The selective electrochemical conversion of glycerol into value-added products is a green and sustainable strategy for the biomass utilization.In this work,Au nanowires(Au-NW)modified with polyethyleneimine(PEI)molecule(Au-NW@PEI)is obtained by an up-bottom post-modification approach.Physical characterization,molecular dynamics simulation and density functional theory demonstrate that the loose-packed PEI monolayer firmly and uniformly distribute on the Au-NW surface due to the strong Au-N interaction.Electrochemical experiments and product analysis display that PEI modification significantly enhance the electro-activity of Au-NW for the glycerol electro-oxidation reaction(GEOR)due to the electronic effect.Meanwhile,the steric hindrance and electrostatic effect of PEI layer make the optimizing adsorption of intermediates possible.Therefore,the selectivity of C3 product glyceric acid over Au-NW@PEI is increased by nearly 20%.The work thus indicates that the rational design of metal-organic interface can effectively elevate the electro-activity and selectivity of Au nanostructures,which may have wide application in biomass development.

Analysis of the strengthening and toughening of a biomaterial interface

Based on the transmission electron micrographs of nacre, the existence of mineral bridges in the organic matrix interface is confirmed. It is proposed that the microarchitecture of nacre should be considered as a “brick-bridge-mortar” (BBM) arrangement rather than traditional “brick and mortar” (BM) one. Experiments and analyses indicate that the mineral bridges effectively affect the strength and toughness of the interfaces in nacre. Comparison with a laminated composite with BM structure, SiC/BN, shows that the pattern of the crack extension and the toughening mechanism of the two materials are different. This reveals that the mineral bridges play a key role in the toughening mechanisms of nacre, which gives a conceptual guidance in material synthesis.

Plasma-enhanced interfacial engineering of FeSiAl@PUA@SiO_(2)hybrid for efficient microwave absorption and anti-corrosion

Microwave absorption materials are prone to degradation in extremely humid and salty environments,and it is still challenging to develop a dense and firm interface to protect microwave absorbers.Herein,a robust FeSiAl@PUA@SiO2(PUA:acrylic polyurethane)gradient hybrid was prepared through plasma-enhanced chemical vapor deposition(PECVD)to achieve efficient microwave absorption and anti-corrosion properties.The organic/inorganic dual coat of PUA/SiO2 not only facilitated the interface polarization but also effectively reduced the dielectric constant and optimized impedance matching.Owing to the unique hybrid structure,the(PECVD-FeSiAl@PUA)@SiO_(2) exhibited highly efficient microwave absorbing performance in frequency bands covering almost the entire Ku-bands(12-18 GHz)with a minimum reflection loss(RLmin)of−47 dB with a matching thickness of 2.3 mm.The organic/inorganic dual protection effectively shields against the corrosive medium,as the corrosion potential and the polarization resistance increased from−0.167 to−0.047 V and 8,064 to 16,273Ω·cm^(2),respectively.While the corrosion current decreased from 3.04×10^(−6) to 2.16×10^(−6) A/cm^(2).Hence,the plasma-enhanced densification of PUA created a strong bridge to integrate FeSiAl and organic/inorganic components acquiring dual-function of efficient microwave absorption and anticorrosion,which opened a promising platform for potential practical absorbers.

Interfacial engineering of printable bottom back metal electrodes for full-solution processed flexible organic solar cells

Printing of metal bottom back electrodes of flexible organic solar cells（FOSCs） at low temperature is of great significance to realize the full-solution fabrication technology. However, this has been difficult to achieve because often the interfacial properties of those printed electrodes, including conductivity, roughness, work function,optical and mechanical flexibility, cannot meet the device requirement at the same time. In this work, we fabricate printed Ag and Cu bottom back cathodes by a low-temperature solution technique named polymer-assisted metal deposition（PAMD） on flexible PET substrates. Branched polyethylenimine（PEI） and ZnO thin films are used as the interface modification layers（IMLs） of these cathodes. Detailed experimental studies on the electrical, mechanical, and morphological properties, and simulation study on the optical properties of these IMLs are carried out to understand and optimize the interface of printed cathodes. We demonstrate that the highest power conversion efficiency over 3.0% can be achieved from a full-solution processed OFSC with the device structure being PAMDAg/PEI/P3 HT：PC61BM/PH1000. This device also acquires remarkable stability upon repeating bending tests.

X-ray microscopic investigation of molecular orientation in a hole carrier thin film for organic solar cells

As dipyranylidenes are excellent hole carriers, applications in organic solar cells or organic light emitting diode are envisaged. In the present study, we investigate the morphology of 2,2＇,6,6＇-tetraphenyl-4,4＇-dipyranylidene （DIPO-Ph4） deposited under vacuum on a silicon nitride （Si3N4） substrate, a paradigmatic system for the study of molecular crystal/inorganic substrate interfaces. Samples with various coating ratios and different thermal treatments were prepared. The films were characterized by atomic force microscopy and scanning transmission X-ray microscopy to gain insight into material growth. The results show a change in orientation at a molecular level depending upon the evaporation conditions. We are now able to tailor an organic layer with a specific molecular orientation and a specific electronic behavior.