attention based on their unique properties such as flexibility, electrical and thermal conductivities, and enhanced p-type [6,9] and modified n-type [10] semiconductor characters. [2,11,12] In low-temperature solution-processable device technologies, such convenient and low energy-consuming processes have prompted exhaustive wide-field research. [13][14][15] Environmentally friendly aqueous dispersion solutions of single-walled CNTs (SWNTs) are industrially applicable; however, we suffer from dispersant molecules seriously insulating electrical communication on solution-processed SWNT film networks. Rinzler et al. overcame the drawback by a breakthrough filter-transfer method using a mixed cellulose ester (MCE) membrane. The filtrated ultra-thin SWNT films were transferred onto substrates by the dissolution removal of MCE (Figure 1, Method A). [16] Jin et al. reported that a floating method of a similarly filtrated SWNT thin film apart from MCE, and the as-floated SWNT film was picked up on a substrate (Method B). [17] See-through perovskite (PVK) solar cells have been successfully prepared using top-contact SWNT thin films [18,19] by a dry filter-transfer method using MCE membranes reported by Kauppinen et al. [20] Simply structured crystalline Si-SWNT heterojunction solar cells have been prepared by the solution-processed [21][22][23][24][25][26][27][28] and dry filter-transfer [29][30][31][32] methods with increasing photo-conversion efficiencies up to ≥17%. [25,31,33,34] See-through solar cells are indispensable for state-of-the-art tandem devices combined with crystalline Si solar cells driven by visible and near IR lights. [35,36] The stability of CNTs against chemical corrosion is a fascinating feature as a top-contact electrode on the PVK layers. The high-conductivity p-type semiconductor character of CNTs with the ≈5 eV work function realizes hole-transport layer-free PVK solar cells. [2,[37][38][39] Therefore, the discovery of a convenient solution-processable technology for preparing top-contact thin films of SWNTs using their aqueous dispersion solutions is key to achieving all solution-processed photovoltaic cells that exclude evaporated metal electrodes and expensive p-type organic semiconductors; however, PVK layers are sensitively decomposed by water, some hydrophilic solvents, and some dissolved chemicals. Furthermore, solution-processable p-type doping technologies of SWNT thin films are crucial Filter-transfer methods of single-walled carbon-nanotube (SWNT) thin films have been widely employed to fabricate state-of-the-art electronics and photonics devices with highly transparent and conductive electrodes; however, a challenge remains for all solution-processable technologies to overcome substrates' destruction due to their solvent incompatibility. Here, an advanced method of transferring SWNT thin films onto arbitrary material substrates by adopting chemically stable and flexible polytetrafluoroethylene (PTFE) membranes is reported. Filtrated SWNT thin films on PTFE membranes (PTFE@SWNTs) pres...

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Low-density films of single-walled carbon nanotubes (SWNTs) can be used as a semi-transparent top electrode for all-solution-processed film devices; however, their semiconductor characteristics vary depending on the experimental factors in their dispersion into solvents, and the sublayers are damaged as a result of solvent incompatibility. In this study, we report a solvent-compatible filter-transfer method for SWNT films stacked with silver nanowires (AgNWs), and evaluate the semiconductor characteristics through the p/n heterojunction with a Si wafer (SWNT/Si). AgNWs and SWNTs were successively filtered through their aqueous dispersion solutions using a membrane filter. The stacked semi-transparent films (AgNW/SWNT films with controlled densities) were successfully transferred onto glass plates and Si wafers. The transmittance at 550 nm revealed a window between 60% and 80% with a narrow sheet resistance range between 11 and 23 Ω □ −1 . The power conversion efficiency (PCE) of SWNT/Si was improved to 11.2% in a junction area of 0.031 cm 2 through the use of spin-coated Nafion resins; however, the accumulated resistance of SWNTs drastically reduced the PCE to 2% as the area increased to ≥0.5 cm 2 . AgNWs maintained the PCE within a range of 10.7% to 8.6% for an area ranging from 0.031 cm 2 to 1.13 cm 2 . All of the photovoltaic parameters were dependent on the junction areas, suggesting that AgNWs function as an effective current-collector layer on the semiconductor layer of SWNTs without direct contact of AgNWs with the Si surface. In addition, we report a solvent-compatible experiment for transferring AgNW/SWNT films onto a solvent-sensitive perovskite material (CH 3 NH 3 PbI 3 ).

The formation of low-temperature solution-processed electrodes from cost-effective and abundant materials is expected to realize all-solution-processed film devices. Silver microplates (AgMLs) can replace metal electrodes formed via high-energy and high-material-consuming processes such as vacuum-evaporation deposition; however, the intrinsic potentials of AgMLs have remained veiled, limiting both industrial applications and scientific research. Here, AgMLs with lateral growth to 3 μm are prepared and filtered through their aqueous dispersion solution on a polytetrafluoroethylene membrane. Assisted by the solvent wettability and flexibility of the membrane, a face-to-face stacked AgML film forms on the membrane and adheres to a glass plate without any external pressure. The film spontaneously transfers onto the plate after the wet solvent evaporates. A low-temperature edge-fusing phenomenon of AgMLs is discovered. Thermogravimetric analysis–synchronized mass spectroscopy reveals that edge fusion is induced from the {100} surfaces of AgMLs by catalytic N–C bond cleavage, which triggers low-temperature decomposition of the surface-protecting polyvinylpyrrolidone at ≤200 °C. The edge fusion markedly improves the volume resistivity of the AgML film to single digits (∼7 μΩ cm), but the resistivity is still higher than 1.6 μΩ cm in bulk silver. We also mention a solvent-compatible method for transferring a AgML film onto solvent-sensitive perovskite materials such as CH3NH3PbI3 and CsPbBr3.