Solution-processed Silver Nanowire Research Articles

Solution-processed silver nanowires as a transparent conducting electrode for air-stable inverted organic solar cells

Highly efficient and air-stable inverted organic solar cells (IOSCs) were fabricated using solution-processed silver nanowire electrodes. The electrodes showed a low sheet resistance of ~16Ωsq−1 and a high transmittance of ~95% at a wavelength of 550nm. A solution-processed ZnO buffer layer is typically used for electron transport and effective passivation of the surface of Ag NW electrodes. The device performance of the IOSCs that used these Ag NW electrodes, which were fabricated on a glass or plastic substrate, was >94% of that of devices containing indium tin oxide (ITO) electrodes. This indicates that solution-processed Ag NW electrode can replace commercialized ITO and can be utilized in roll-to-roll and large-area fabrication processes.

Silver nanowire composite thin films as transparent electrodes for Cu(In,Ga)Se₂/ZnS thin film solar cells.

Solution processed silver nanowire indium-tin oxide nanoparticle (AgNW-ITONP) composite thin films were successfully applied as the transparent electrodes for Cu(In,Ga)Se₂ (CIGS) thin film solar cells with ZnS buffer layers. Properties of the AgNW-ITONP thin film and its effects on performance of CIGS/ZnS thin film solar cells were studied. Compared with the traditional sputtered ITO electrodes, the AgNW-ITONP thin films show comparable optical transmittance and electrical conductivity. Furthermore, the AgNW-ITONP thin film causes no physical damage to the adjacent surface layer and does not need high temperature annealing, which makes it very suitable to use as transparent conductive layers for heat or sputtering damage-sensitive optoelectronic devices. By using AgNW-ITONP electrodes, the required thickness of the ZnS buffer layers for CIGS thin film solar cells was greatly decreased.

Polymer Embedded Silver-Nanowire Network Structures – A Platform for the Facile Fabrication of Flexible Transparent Conductors

Solution-processed silver nanowire (Ag-NW) network structures are candidate materials for application as flexible transparent conductors in a wide range of flexible electronics. However, challenges remain in fabricating these materials in an efficient and scalable manner in addition to making them mechanically robust. Here, a method based on the direct processing of Ag-NW network structures from aqueous polymer solutions is presented that significantly increases the uniformity of the NW networks and lowers the percolation threshold, thus resulting in an increased figure of merit (percolative FoM Π > 40) of Ag-NW based transparent conductors. Direct polymer solution processing also reduces the batch-to-batch variability of optical and electrical properties of the NW networks to <5% of the mean (as compared to 10–20% variability for pristine Ag-NW networks), and significantly improves their resistance to mechanical deformation. Our results further indicate that semicrystalline polymers such as poly (vinyl alcohol) (PVA) could serve as viable and benign alternatives to conducting polymer matrices (such as PEDOT:PSS) that pose a challenge to device fabrication due to their corrosive properties.

Cu(In,Ga)Se2 Thin Film Solar Cells with Solution Processed Metal Nanowire Based Transparent Conductor

Since the traditional sputtered metal oxide thin films are not suited for using as transparent electrodes of flexible thin film solar cells and their increasing prices limit development of solar cells industry, high performance, low cost and flexible transparent conductor technology has aroused researchers’ great interests. In this paper, we successfully apply a solution processed silver nanowire composite film as the transparent electrode for Cu(In,Ga)Se2 thin film solar cells with ZnS buffer layers. Compared with traditional sputtered window layer, the solution processed transparent electrode causes no physical damage to the adjacent device layers and junction region, which can greatly decrease the required thickness of the ZnS buffer layer. Properties of the silver nanowire composite transparent conductor and its effects on performance of Cu(In,Ga)Se2/ZnS thin film solar cells are studied.

Current–voltage characteristics of fully solution processed high performance CuIn(S,Se)2 solar cells: Crossover and red kink

We recently reported the successful replacement of both sputtered intrinsic zinc oxide (i-ZnO) and sputtered indium tin oxide (ITO) window layers by a solution processed silver nanowire composite window (SNCW) layer for fully solution processed high performance CuIn(S,Se)2 (CISS) thin film solar cells without any sacrifices in photovoltaic device performance. Here, we report the current density–voltage (J–V) characteristics of the fully solution processed CISS thin film solar cells with the SNCW layer under dark conditions, and under white and filtered red-light illumination. While control devices with sputtered conductive metal oxide window layers do not show J–V distortion, devices with the SNCW exhibit both crossover and red kink behaviors, which disappear during white-light illumination but gradually re-appear after turning off light. We propose the following model to explain the above observations. Acceptor-like defects at the CdS/SNCW interface become negatively charged by capturing electrons under dark conditions, but are neutralized by capturing photo-generated holes from the CdS valence band under white-light illumination. The illumination dependent state of the acceptor-like defects leads to the appearance and disappearance of the crossover and red kink from the J–V curves.

High fill factor polymer solar cells comprising a transparent, low temperature solution processed doped metal oxide/metal nanowire composite electrode

In this paper we report on the replacement for the commonly used ITO electrode material by a low temperature solution processed silver nanowire/(doped) metal oxide composite. Devices employing silver nanowires (AgNWs)/buffer layer electrodes with a photoactive layer of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) are showing a comparable performance to the ITO reference cell with fill factors (FF) of over 62% and a power conversion efficiency of ∼2.7%. Zinc oxide (ZnO) and highly conductive Al doped ZnO (AZO) are used as buffer layer. AgNW devices without a buffer layer have a high open circuit voltage (VOC) but the FF and the short circuit current density (jSC) are substantially lower. Overall it is demonstrated that AgNWs and the low temperature solution process of the buffer layer are an attractive device concept towards an indium free organic solar cell.

Laminating solution-processed silver nanowire mesh electrodes onto solid-state dye-sensitized solar cells

Solution processed silver nanowire meshes (Ag NWs) were laminated on top of solid-state dye-sensitized solar cells (ss-DSCs) as a reflective counter electrode. Ag NWs were deposited in <1 min and were less reflective compared to evaporated Ag controls; however, AgNW ss-DSC devices consistently had higher fill factors (0.6 versus 0.69), resulting in comparable power conversion efficiencies (2.7%) compared to thermally evaporated Ag control (2.8%). Laminated Ag NW electrodes enable higher throughput manufacturing and near unity material usage, resulting in a cheaper alternative to thermally evaporated electrodes.