Donor-acceptor polymer-fullerene-based bulk heterojunction (BHJ) photovoltaic cells have many advantages; specifi cally, they can be fabricated in large-areas with simple solution methods involving a low-cost roll-to-roll manufacturing process. [1][2][3][4][5][6][7] The active layer in BHJ solar cells provides charge generation, separation, transport, and collection. During these steps, sweep-out of photo-generated carriers competes with charge recombination within the BHJ due to low carrier mobility. [8][9][10] Blocking the recombination is a key method of increasing device efficiency. [ 11 ] Therefore, we need to decrease the thickness of the active layer of BHJ fi lm and maximize its absorption capability to reduce the likelihood of recombination and thereby improve the effi ciency of the device.Metallic silver (Ag) nanoparticles (NPs) can be effective in thin fi lm solar cells because of their localized surface plasmon resonance, which can increase the light absorption capability of an active layer within a range of wavelengths. Thus, the addition of metal NPs into a BHJ active layer can potentially enhance the absorption and increase the photo-generation of mobile carriers. Several groups have recently reported that, when combined, polymer and metal NPs improve light absorption and cell effi ciency. [12][13][14][15] To ensure that metal NPs have positive effects in organic photovoltaic devices (OPVs), we must diminish the possibility of transferring nonradiative energy, which quenches excitons in the BHJ active layer. [ 12 , 15 ] Because of this concern, most researchers add metal NPs to the interface of the indium tin oxide (ITO) anode and the BHJ active layer; alternatively, they embed the metal NPs in a poly(3,4-ethylene dioxythiophene:poly(styrene sulfonate) (PEDOT:PSS) hole transporting interlayer to induce plasmon excitation within the thin BHJ fi lm. [ 12 , 16 , 17 ] However, Kim and Carroll directly added Ag or Au NPs to a BHJ polymer and confi rmed that the cell effi ciency was enhanced by the improved electrical conductivity. [ 13 ] The simple method of directly mixing metal NPs in an active layer is attractive because it enhances the overall performance of the cell. Specifi cally, this method can reduce the device resistance; [ 13 ] furthermore, the incident light can be refl ected and scattered by the embedded metal NPs while passing through the active layer, thereby increasing the optical path length of the incident light.Our study demonstrates several positive effects that arise from the addition of Ag NPs with controlled diameter size in BHJ photovoltaic cells fabricated with poly[N-9"-hepta-decanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole) (PCDTBT)/ [6,6]-phenyl C 70 butyric acid methyl-ester (PC 70 BM). Using effective, easily processable solution chemistry of a polyol process, we can synthesize Ag particles with wellcontrolled sizes and well-defi ned shapes. Specifi cally, we produced particles with diameters of 30 nm, 40 nm, and 60 nm. These Ag NPs have differe...

Crack-based strain sensor systems have been known for its high sensitivity, but suffer from the small fracture strain of the thin metal films employed in the sensor which results in its negligible stretchability. Herein, we fabricated a transparent (>90% at 550 nm wavelength), stretchable (up to 100%), and sensitive (gauge factor (GF) of 30 at 100% strain) strain gauge by depositing an encapsulated crack-induced Ag nanowire (AgNW) network on a hydroxylated poly(dimethylsiloxane) (PDMS) film. Stretching the encapsulated AgNWs/PDMS resulted in the formation of a percolation network of nanowire ligaments with abundant percolation paths. The encapsulating polymer was designed to adhere strongly to both the AgNW and PDMS. The improved adhesion ensured the resistance of the crack-induced network of AgNWs varied reversibly, stably, and sensitively when stretched and released, at strains of up to 100%. The developed sensor successfully detected human motions when applied to the skin.

The size of silver nanocrystals in polyol synthesis can be simply controlled by tuning the viscosity of the reaction medium such as ethylene glycol, 1,2-propanediol, 1,4-butanediol and 1,5-pentanediol. We found that a higher viscose medium (1,5-pentanediol) led to monodispersed smaller particles thanks to the slow addition of silver atoms into the nuclei. Size-controlled silver nanocrystals of 30 nm were obtained in a viscosity controlled medium of 1,5-pentanediol to synthesize a low refractive index filler by coating with silica and subsequent etching of the silver core. The coated low-reflection layer from the hollow silica nanoparticles on polyethylene terephthalate (PET) film can greatly reduce the reflection of the PET film from 10% to 2% over the entire visible region.

Electrically bistable Ag nanocrystal-embedded metal–organic frameworks (MOF) were synthesized using a one-pot synthetic method by introducing melamine into a polyol process for the synthesis of Ag nanocrystals.

The efficiency of polymer light-emitting diodes was improved by synergistic effect of enhanced hole transport from mercaptoacids molecules and resonant coupling of Ag NPs introduced by ligand-exchange process.