We report a comprehensive study of transparent and conductive silver nanowire (Ag NW) electrodes, including a scalable fabrication process, morphologies, and optical, mechanical adhesion, and flexibility properties, and various routes to improve the performance. We utilized a synthesis specifically designed for long and thin wires for improved performance in terms of sheet resistance and optical transmittance. Twenty Omega/sq and approximately 80% specular transmittance, and 8 ohms/sq and 80% diffusive transmittance in the visible range are achieved, which fall in the same range as the best indium tin oxide (ITO) samples on plastic substrates for flexible electronics and solar cells. The Ag NW electrodes show optical transparencies superior to ITO for near-infrared wavelengths (2-fold higher transmission). Owing to light scattering effects, the Ag NW network has the largest difference between diffusive transmittance and specular transmittance when compared with ITO and carbon nanotube electrodes, a property which could greatly enhance solar cell performance. A mechanical study shows that Ag NW electrodes on flexible substrates show excellent robustness when subjected to bending. We also study the electrical conductance of Ag nanowires and their junctions and report a facile electrochemical method for a Au coating to reduce the wire-to-wire junction resistance for better overall film conductance. Simple mechanical pressing was also found to increase the NW film conductance due to the reduction of junction resistance. The overall properties of transparent Ag NW electrodes meet the requirements of transparent electrodes for many applications and could be an immediate ITO replacement for flexible electronics and solar cells.

Transparent conductive electrodes are important components of thin-film solar cells, light-emitting diodes, and many display technologies. Doped metal oxides are commonly used, but their optical transparency is limited for films with a low sheet resistance. Furthermore, they are prone to cracking when deposited on flexible substrates, are costly, and require a high-temperature step for the best performance. We demonstrate solution-processed transparent electrodes consisting of random meshes of metal nanowires that exhibit an optical transparency equivalent to or better than that of metal-oxide thin films for the same sheet resistance. Organic solar cells deposited on these electrodes show a performance equivalent to that of devices based on a conventional metal-oxide transparent electrode.

Wearable electronics represent a significant paradigm shift in consumer electronics since they eliminate the necessity for separate carriage of devices. In particular, integration of flexible electronic devices with clothes, glasses, watches, and skin will bring new opportunities beyond what can be imagined by current inflexible counterparts. Although considerable progresses have been seen for wearable electronics, lithium rechargeable batteries, the power sources of the devices, do not keep pace with such progresses due to tenuous mechanical stabilities, causing them to remain as the limiting elements in the entire technology. Herein, we revisit the key components of the battery (current collector, binder, and separator) and replace them with the materials that support robust mechanical endurance of the battery. The final full-cells in the forms of clothes and watchstraps exhibited comparable electrochemical performance to those of conventional metal foil-based cells even under severe folding-unfolding motions simulating actual wearing conditions. Furthermore, the wearable textile battery was integrated with flexible and lightweight solar cells on the battery pouch to enable convenient solar-charging capabilities.

We demonstrate organic photovoltaic cells in which every layer is deposited by solution processing on opaque metal substrates, with efficiencies similar to those obtained in conventional device structures on transparent substrates. The device architecture is enabled by solution-processed, laminated silver nanowire films serving as the top transparent anode. The cells are based on the regioregular poly(3-hexylthiophene) and C(61) butyric acid methyl ester bulk heterojunction and reach an efficiency of 2.5% under 100 mW/cm(2) of AM 1.5G illumination. The metal substrates are adequate barriers to moisture and oxygen, in contrast to transparent plastics that have previously been used, giving rise to the possibility of roll-to-roll solution-processed solar cells that are packaged by lamination to glass substrates, combining the cost advantage of roll-to-roll processing with the barrier properties of glass and metal foil.

Perovskite light-emitting diodes have recently broken the 20% barrier for external quantum efficiency. These values cannot be explained with classical models for optical outcoupling. Here, we analyse the role of photon recycling (PR) in assisting light extraction from perovskite light-emitting diodes. Spatially-resolved photoluminescence and electroluminescence measurements combined with optical modelling show that repetitive re-absorption and reemission of photons trapped in substrate and waveguide modes significantly enhance light extraction when the radiation efficiency is sufficiently high. In this manner, PR can contribute more than 70% to the overall emission, in agreement with recently-reported high efficiencies. While an outcoupling efficiency of 100% is theoretically possible with PR, parasitic absorption losses due to absorption from the electrodes are shown to limit practical efficiencies in current device architectures. To overcome the present limits, we propose a future configuration with a reduced injection electrode area to drive the efficiency toward 100%.

In this report, we propose a metal-metal core-shell nanocube (NC) as an advanced plasmonic material for highly efficient organic solar cells (OSCs). We covered an Au core with a thin Ag shell as a scattering enhancer to build Au@Ag NCs, which showed stronger scattering efficiency than Au nanoparticles (AuNPs) throughout the visible range. Highly efficient plasmonic organic solar cells were fabricated by embedding Au@Ag NCs into an anodic buffer layer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and the power conversion efficiency was enhanced to 6.3% from 5.3% in poly[N-9-hepta-decanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)] (PCDTBT):[6,6]-phenyl C71-butyric acid methyl ester (PC70BM) based OSCs and 9.2% from 7.9% in polythieno[3,4-b]thiophene/benzodithiophene (PTB7):PC70BM based OSCs. The Au@Ag NC plasmonic PCDTBT:PC70BM-based organic solar cells showed 2.2-fold higher external quantum efficiency enhancement compared to AuNPs devices at a wavelength of 450-700 nm due to the amplified plasmonic scattering effect. Finally, we proved the strongly enhanced plasmonic scattering efficiency of Au@Ag NCs embedded in organic solar cells via theoretical calculations and detailed optical measurements.

Silver nanowire (AgNW) random meshes have attracted considerable attention as flexible and high-performance transparent electrodes. Notably, post-treatment of the AgNW random meshes, such as thermal annealing, is usually required to guarantee comparable optical transparency and electrical conductivity to commercial indium tin oxide (ITO). Here, the integral elements of preparing a high-performance, large-area AgNW random mesh network are discussed. High-performance nanostructured transparent electrodes can be obtained without any post-treatment, thereby relieving the restrictions related to the substrate. Solvent washing and a large-area spray-coating method effectively reduce the wire-wire contact resistances, thus reducing or eliminating the requirement for post-treatment.

We demonstrate semitransparent small molecular weight organic photovoltaic cells using a laminated silver nanowire mesh as a transparent, conductive cathode layer. The lamination process does not damage the underlying solar cell and results in a transparent electrode with low sheet resistance and high optical transmittance without impacting photocurrent collection. The resulting semitransparent phthalocyanine/fullerene organic solar cell has a power conversion efficiency that is 57% of that of a device with a conventional metal cathode due to differences in optical absorption. KEYWORDS Organic photovoltaics, transparent electrodes, nanowiresO rganic photovoltaic cells are considered a promising solar cell technology because of the tunability of the electronic and optical properties of organic semiconductors and the potential for low-cost roll-to-roll manufacturing. However, the relatively low efficiency of organic solar cells is a major roadblock that stands in the way of commercialization. A plausible path toward higher conversion efficiencies is the use of multijunction cell architectures where several individual cells with different optical gaps are combined into a series-connected stack, 1-3 as shown in Figure 1a. However, the requirement that each cell in the series-connected stack produce the same photocurrent, limits this approach. This is especially the case when an optimized material system 4 is combined with one that is not yet optimized, or when the energy gaps of the materials are not ideal. In multijunction architectures in which the cells are individually accessible and photocurrent matching is not required, as shown in Figure 1b, higher efficiencies can be achieved 4 for a given number of subcells. Such an arrangement requires a transparent conductor 5-13 between adjacent subcells that makes an ohmic contact to both subcells while being transparent and conductive in the plane to ensure that current can be extracted without ohmic losses. Furthermore, this electrode must be deposited on top of an organic solar cell without incurring damage to the underlying cell. Here, we describe such an electrode that satisfies all the above requirements.A transparent polymer cathode that can be laminated on top of an organic photovoltaic cell was previously reported, 14 but device performance suffered due to the relatively low conductivity (10 2 ∼10 3 S/cm) of the polymer layer. Indiumtin-oxide (ITO) transparent cathode layers sputter-deposited at low plasma powers and hence low deposition rates have also been used. 15,16 However, the slow and therefore expensive sputtering process used is undesirable and damages the underlying organic active layer leading to lower device performance. 17 Thin, semitransparent metal films have been used as transparent electrodes and exhibit good performance, albeit not identical to sputter-coated ITO, if optical interference effects can be exploited. 7,18,19 In multijunction configurations, the additional reflections of the metal films are likely to substantially complica...