Self-Assembled Monolayers (SAMs) in Organic Field-Effect Transistors

This Account describes a body of research on the design, synthesis, and application of a new class of electronic materials made from conjugated macrocycles. Our macrocyclic design takes into consideration the useful attributes of fullerenes and what properties make fullerenes efficient n-type materials. We identified four electronic and structural elements: (1) a three-dimensional shape; (2) a conjugated and delocalized π-space; (3) the presence of an interior and exterior to the π-surface; and (4) low-energy unoccupied molecular orbitals allowing them to accept electrons. The macrocyclic design incorporates some of these properties, including a three-dimensional shape, an interior/exterior to the π-surface, and low-lying LUMOs maintaining the n-type semiconducting behavior, yet we also install synthetic flexibility in our approach in order to tune the properties further. Each of the macrocycles comprises perylenediimide cores wound together with linkers. The perylenediimide building block endows each macrocycle with the ability to accept electrons, while the synthetic flexibility to install different linkers allows us to create macrocycles with different electronic properties and sizes. We have created three macrocycles that all absorb well into the visible range of the solar spectrum and possess different shapes and sizes. We then use these materials in an array of applications that take advantage of their ability to function as n-type semiconductors, absorb in the visible range of the solar spectrum, and possess intramolecular cavities. This Account will discuss our progress in incorporating these new macrocycles in organic solar cells, organic photodetectors, organic field effect transistors, and sensors. The macrocycles outperform acyclic controls in organic solar cells. We find the more rigid macrocyclic structure results in less intrinsic charges and lower dark current in organic photodetectors. Our macrocyclic-based photodetector has the highest detectivity of non-fullerene acceptors. The macrocycles also function as sensors and are able to recognize nuanced differences in analytes. Perylenediimide-based fused oligomers are efficient materials in both organic solar cells and field effect transistors. We will use the oligomers to construct macrocycles for use in solar energy conversion. In addition, we will incorporate different electron-rich linkers in our cycles in an attempt to engineer the HOMO/LUMO gap further. Looking further into the future, we envision opportunities in applying these conjugated macrocycles as electronic host/guest materials, as concatenated electronic materials by threading the macrocycles with electroactive oligomers, and as a locus for catalysis that is driven by light and electric fields.

Semiconductor nanowires are an emerging class of materials with great potential for applications in future electronic devices. The small footprint and the large charge-carrier mobilities of nanowires make them potentially useful for applications with high-integration density, but also to replace thin-film transistors in large-area electronics. This thesis investigates the use of wet-chemically grown ZnO nanowires for the fabrication of high-performance, low-voltage field-effect transistors (FETs). The first part of this thesis addresses the electrical characteristics of the wet-chemically grown ZnO nanowires. The as-grown ZnO nanowires are highly conductive due to a large charge-carrier concentration caused by dopants unintentionally incorporated into the ZnO nanowires during the synthesis. This large charge-carrier concentration makes it difficult to modulate the conductivity of the nanowires by an external electric field, so that the as-grown wires are not suitable for FETs. A post-growth annealing step is employed to dramatically reduce the charge-carrier concentration of the nanowires which makes it possible to fabricate FETs with useful characteristics. ZnO-nanowire FETs in a global back-gate geometry based on annealed ZnO nanowires have a transconductance of 300 nS, an on/off current ratio of 107 and a subthrehold slope of 500 mV/decade. The maximum field-effect mobility of the annealed ZnO nanowires is around 50 cm2/Vs. An important requirement to obtain good FET characterisitcs is to minimize the influence of the source and drain contact resistance on the total device resistance. The material used for the source and drain contacts in this thesis is aluminum. It is demonstrated that the use of a plasma treatment in the contact regions prior to the evaporation of the aluminum contacts can greatly influence the contact properties between ZnO and aluminum. An argon-plasma treatment locally increases the charge-carrier concentration in the ZnO. It is shown that the doping effect of the argon-plasma treatment can be exploited to reduce the contact resistance between alumiunm and ZnO and improve the electrical performance of the FETs. In the second part of this thesis, the influence of the ambient air on the electrical characteristics of the ZnO-nanowire FETs is investigated. The electrical conductivity of the FETs is strongly affected by the distinct atmospheric conditions, which makes it difficult to obtain reliable FET characteristics. The potential of a self-assembled monolayer (SAM) based on fluoroalkylphosphonic acid molecules to passivate the ZnO nanowires against the undesirable effects of the ambient and to stabilize the electrical performance of ZnO-nanowire FETs is demonstrated. The stabilizing effect is attributed to the formation of a densely packed, hydrophobic SAM on the surface of ZnO and aluminum oxide. The quality of the hydrophobic SAMs is confirmed by means of water-contact-angle measurements on SAM-covered ZnO single crystals that show a contact angle of more than 110°. The third part of this thesis is dedicated to the fabrication of high-performance ZnO-nanowire FETs with patterned metal top-gate electrodes. A top-gate fabrication process is developed that uses a very thin gate dielectric consisting only of an alkylphosphonic acid SAM that can be deposited from solution. The insulating quality of the SAM is investigated for top-gate FETs that utilize either gold or aluminum for the top-gate electrode. Gold top-gate FETs show a transconductance of 1 µS, an on/off current ratio of 107, and a steep subthreshold slope of 90 mV/decade. The thin gate dielectric makes it possible to operate the gold top-gate FETs at low voltages of 1 V and simultaneously reduces the undesired gate current by more than three orders of magnitude compared to gold top-gate FETs that have been fabricated without a gate dielectric (MESFETs). The gate current of the gold top-gate FETs with SAM gate dielectric is as low as 1 pA for gate-source voltages between -1 V and 0.5 V. When aluminum is used for the top-gate electrode, a hybrid dielectric is formed at the interface between the SAM and the aluminum, consisting of the SAM and a spontaneously formed aluminum oxide layer. Owing to the hybrid gate dielectric, the aluminum top-gate FETs are operated with gate currents below 1 pA for voltages up to 3 V. The top-gate fabrication process does not require temperatures above 160 °C, which makes it possible to fabricate FETs on unconventional substrates that cannot tolerate high temperatures, such as glass or flexible plastics. Integrated circuits on single ZnO nanowires that are fabricated on glass and plastic substrates are demonstrated. The maximum switching frequency of the inverters is 1 MHz.

Modeling of bias-induced changes of organic field-effect transistor characteristics

This review provides a comprehensive overview of the development and applications of conjugated polymer semiconductors. The review summarizes the current state of research in this field, including the synthesis and characterization of these materials, their properties, and potential applications. The scope covers a wide range of topics, including organic photovoltaics, organic field-effect transistors, and conjugated polymer nanoparticles. The main findings highlight the significant progress that has been made in this field, with conjugated polymers exhibiting favorable electronic and optical properties, as well as high charge mobility. These materials have shown great potential for use in various applications, including solar cells, light-emitting diodes, and field-effect transistors. The applications are far-reaching, with the potential to revolutionize the electronics industry by providing low-cost, flexible, and environmentally friendly alternatives to traditional inorganic materials. One of the key challenges facing this field is the need to improve the efficiency and stability of conjugated polymer-based devices. While significant progress has been made in this area, there is still much work to be done to develop materials and device architectures that can achieve high performance over extended periods of time. Another challenge is the need to develop scalable manufacturing processes that can produce large quantities of high-quality conjugated polymers at a reasonable cost. The continued advancement of this field holds great promise for the development of new technologies that can improve our lives and help to address some of the world’s most pressing challenges.

Achieving high mobility and bias stability is a challenging obstacle in the advancement of organic thin-film transistors (OTFTs). To this end, the fabrication of high-quality organic semiconductor (OSC) thin films is critical for OTFTs. Self-assembled monolayers (SAMs) have been used as growth templates for high-crystalline OSC thin films. Despite significant research progress in the growth of OSC on SAMs, a detailed understanding of the growth mechanism of the OSC thin films on a SAM template is lacking, which has limited its use. In this study, the effects of the structure (thickness and molecular packing) of SAM on the nucleation and growth behavior of the OSC thin films were investigated. We found that disordered SAM molecules assisted in the surface diffusion of the OSC molecules and resulted in a small nucleation density and large grain size of the OSC thin films. Moreover, a thick SAM with disordered SAM molecules on the top was found to be beneficial for the high mobility and bias stability of the OTFTs.

The perovskite solar cells (PSCs) and organic solar cells (OSCs) with high performance were fabricated with transfer-printed top metal electrodes. We have demonstrated that PSCs and OSCs with the top Au electrodes fabricated by using the transfer printing method have comparable or better performance than the devices with the top Au electrodes fabricated by using the conventional thermal evaporation method. The highest PCE of the PSCs and OSCs with the top electrodes fabricated using the transfer printing method achieved 13.72% and 2.35%, respectively. It has been investigated that fewer defects between the organic thin films and Au electrodes exist by using the transfer printing method which improved the device stability. After storing the PSCs and OSCs with the transfer-printed electrodes in a nitrogen environment for 97 and 103 days without encapsulation, the PSCs and OSCs still retained 71% and 91% of their original PCEs, respectively.

The majority of organic semiconductors developed are more easily oxidized (p-type) than reduced (n-type). However, n-type organic semiconductors are important for a range of optoelectronic applications including organic photovoltaic devices, light-emitting diodes and field effect transistors (FETs). In spite of this there has been significantly less development of n-type compounds. This project focused on developing novel n-type semiconductors for use in organic photovoltaic devices. To identify the organic acceptor candidates, a series of novel materials were synthesized and characterized. Amongst these materials, 2-[(7-{9,9-di-n-propyl-9H-fluoren-2-yl}benzo[c][1,2,5]thiadiazol-4-yl)methylene]malononitrile (K12) was identified as a lead candidate. K12 has the remarkable property in that it can be deposited from solution or by evaporation. K12 exhibits a tendency to order in the solid state at room temperature, and with mild heating the process can be accelerated. The extent of ordering in the films was followed by Polarized Optical Microscopy, Atomic Force Microscopy, and Wide Angle X-ray Diffraction. K12 was found to be a good electron acceptor candidate for bulk heterojunction organic solar cells and as an active channel in organic field effect transistors (OFETs). A 0.7% power conversion efficiency under AM1.5 light was achieved in a bulk heterojunction solar cell configuration with poly(3-n-hexylthiophene) as the donor. The thermal properties of K12 enable the film morphology to be controlled at easily accessible temperatures allowing the charge mobility to be tuned over two orders of magnitude. The electron mobility in the films was found to be independent of the initial processing conditions (solution or evaporation). The electron mobility measured in a FET configuration was of order 10-3 cm2/Vs for films prepared via either processing method whilst Photoinduced Charge Extraction in Linearly Increasing Voltage (PhotoCELIV) for annealed films gave a mobility of order 10-4 cm2/Vs. To further tune the properties of K12 several chemical modifications were made. To harvest more of the solar spectrum derivatives with electron donating groups such as thiophene (K12-Th) and diphenylamine (K12-Diph) were prepared to extend the conjugation length and form a Donor-Acceptor structure. Amongst the derivatives K12-Diph gave a greatly broadened absorption ranging between 200 nm and 800 nm. The dipole moment of K12 was found to play an important role in its morphology and hence K12b, which has a smaller dipole moment was prepared to investigate this effect further. It was found that the different dipole moments of K12 and K12b had dramatic effects on both the physical properties, reflected in their thermal properties and molecular packing. The morphological differences in films comprised of the each of the materials were observed to have a direct impact on the device performance in both OFET and OPV devices. The propensity of K12 to crystallize was found to give rise to better charge transport than K12b. Macromolecular structures K12-3 and K12-6 (with three and six K12 chromophores around a central benzene ring, respectively) were prepared. Although they had similar fundamental optoelectronic properties to K12 their physical properties were altered and although they could be solution processed did not form films that gave enhanced charge transport due to aggregation effects.

Functionalization of Organic Semiconductors and Other Carbon-based Materials by Self-Assembled Monolayers (SAMs) and Charge Transport in Organic Field-effect Transistors (OFETs)

In organic thin-film transistors (OTFTs), the conducting channel is located near the interface between the organic semiconductor and the dielectric; this interface is crucial for transistor performance. The goal of this thesis is to study the effect of this interface, especially when it is modified either by surface treatments or self-assembled monolayers. For this purpose, OTFTs based on pentacene and doped silicon wafer gate electrode and gold top contacts are fabricated. The dielectric is either silicon oxide (SiO2) or polyimide (PI). The dielectric surface affects both the growth of the pentacene film on the top of it and the electric performance of the transistor. The pentacene film morphology is studied on treated and untreated SiO2 and PI surfaces by AFM and water contact angle measurements. Depending on the nature of the dielectric surface, traps or charge transfer centers are introduced which then affect the performance of the transistor. The transistor performance is determined by measuring the drain current as it is dependent upon the drain and gate voltage. The contributions of the channel and the contacts are separated by 4-probe measurements (at floating and non-floating gate). The transistors with untreated dielectrics are first characterized. The dependence on the channel length, the thickness and the morphology of the pentacene film is studied. The short channels (2 – 20 µm) are patterned by stencil masks; the long channels (100 – 600 µm) by steel masks. The results show that the transistors with a channel length of 20 µm and smaller are limited by the contacts, while the transistors with a channel length between 100 and 600 µm are dominated by the channel, and thus the traps and residual carriers in the channel. The pentacene film morphology has more influence on the contact resistance than on the channel behavior. To study the effect of the interface modifications, the transistor behavior should be dominated by the channel and the contact effects minimized; hence, long-channel transistors are used. The dielectric surfaces are treated by plasma or pH solutions prior to the pentacene deposition resulting in a variety of defects. The defects are distinguished by those which lead to a change in the film growth and those which affect the electric performance by introducing traps or charge transfer centers. To overcome the influence of the dielectric surface, the oxide dielectric is passivated by a self-assembled monolayer (SAM). The neutral SAM acts as a spacer between the dielectric and the pentacene film and thus enhances the transistor performance. The polar SAMs also introduce a dipole moment. A series of molecules with a similar length, but different end groups, are used to investigate the effect of the dipole moment. The main result of this study is that the nature and the quality of the gate and the contact interfaces are often more important for the performance of the transistors than the thin film morphology.

approches numériques du transport de charges dans les semiconducteurs organiques

We successfully demonstrated a detailed and systematic enhancement of organic field effect transistors (OFETs) performance using dithienothiophene (DTT) and furan-flanked diketopyrrolopyrrole based donor–acceptor conjugated polymer semiconductor namely PDPPF-DTT as an active semiconductor. The self-assembled monolayers (SAMs) treatments at interface junctions of the semiconductor–dielectric and at the semiconductor–metal electrodes has been implemented using bottom gate bottom contact device geometry. Due to SAM treatment at the interface using tailored approach, the significant reduction of threshold voltage (Vth) from − 15.42 to + 5.74 V has been observed. In addition to tuning effect of Vth, simultaneously charge carrier mobility (µFET) has been also enhanced the from 9.94 × 10−4 cm2/Vs to 0.18 cm2/Vs. In order to calculate the trap density in each OFET device, the hysteresis in transfer characteristics has been studied in detail for bare and SAM treated devices. Higher trap density in Penta-fluoro-benzene-thiol (PFBT) treated OFET devices enhances the gate field, which in turn controls the charge carrier density in the channel, and hence gives lower Vth = + 5.74 V. Also, PFBT treatment enhances the trapped interface electrons, which helps to enhance the mobility in this OFET architecture. The overall effect has led to possibility of reduction in the Vth with simultaneous enhancements of µFET in OFETs, following systematic device engineering methodology.

The choice of appropriate building blocks and the development of new donor and acceptor units are essential for the creation of high-performance donor-acceptor (D-A)-type semiconducting polymers. In addition, the introduction of π-extended aromatic frameworks into polymer main chains is a useful strategy to facilitate dense π-π stacking structures with long-range order in the solid-state, thereby enabling efficient carrier transport in organic electronics. However, such highly π-extended aromatic frameworks have rarely been reported due to the need for multiple steps. This focus review describes the synthesis and characterization of D-A polymers based on three π-extended heteropolycyclic aromatic frameworks, using phenanthro[1,2-b:8,7-b’]dithiophene (PDT) as a weak donor and alkoxy-substituted anthra[1,2‑c:5,6‑c’]bis([1,2,5]thiadiazole) (ATz) and vinylene-bridged 5,6-difluorobenzo[c][1,2,5]thiadiazole (FBTzE) as new thiadiazole-based acceptor units. In addition, their applications to organic electronic devices, such as organic field-effect transistors (OFETs) and organic photovoltaic cells (OPVs), and the detailed relationship between the thin-film structure and device performance in OFETs and OPVs were investigated. These results indicate that these novel π-extended heteropolycyclic aromatic frameworks may serve as building units for the development of wide-bandgap p-type semiconducting polymers for nonfullerene solar cells and low-bandgap n-type semiconducting polymers for OFETs and OPVs. Our recent studies on the development of semiconducting polymers based on three novel π-extended heteropolycyclic aromatic frameworks, using phenanthro[1,2-b:8,7-b’]dithiophene (PDT) as a weak donor and alkoxy-substituted anthra[1,2‑c:5,6‑c’]bis([1,2,5]thiadiazole) (ATz) and vinylene-bridged 5,6-difluorobenzo[c][1,2,5]thiadiazole (FBTzE) as new thiadiazole-based acceptor units are described. Furthermore, their detailed relationships between the thin-film structure and device performance in organic field-effect transistors (OFETs) and organic photovoltaic cells (OPVs) were investigated. These results demonstrated that these novel π-extended heteropolycyclic aromatic frameworks have great potential as building units for high-performance OFETs and OPVs.

Organic semiconductors devices, such as, organic solar cells (OSCs), organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs) have drawn increasing interest in recent decades. As organic materials are flexible, light weight, and potentially low-cost, organic semiconductor devices are considered to be an alternative to their inorganic counterparts. This dissertation will focus mainly on OSCs and OLEDs. As a clean and renewable energy source, the development of OSCs is very promising. Cells with 9.2% power conversion efficiency (PCE) were reported this year, compared to < 8% two years ago. OSCs belong to the so-called third generation solar cells and are still under development. While OLEDs are a more mature and better studied field, with commercial products already launched in the market, there are still several key issues: (1) the cost of OSCs/OLEDs is still high, largely due to the costly manufacturing processes; (2) the efficiency of OSCs/OLEDs needs to be improved; (3) the lifetime of OSCs/OLEDs is not sufficient compared to their inorganic counterparts; (4) the physics models of the behavior of the devices are not satisfactory. All these limitations invoke the demand for new organic materials, improved device architectures, low-cost fabrication methods, and better understanding of device physics. For OSCs, we attempted to improve the PCE by modifying the interlayer between active layer/metal. We found that ethylene glycol (EG) treated poly(3,4-ethylenedioxythiophene): polystyrenesulfonate (PEDOT: PSS) improves hole collection at the metal/polymer interface, furthermore it also affects the growth of the poly(3- hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) blends, making the phase segregation more favorable for charge collection. We then studied organic/inorganic tandem cells. We also investigated the effect of a thin LiF layer on the hole-collection of copper phthalocyanine (CuPc)/C70-based small molecular OSCs. A thin LiF layer serves typically as the electron injection layer in OLEDs and electron collection interlayer in the OSCs. However, several reports showed that it can also assist in holeinjection in OLEDs. Here we first demonstrate that it assists hole-collection in OSCs, which is more obvious after air-plasma treatment, and explore this intriguing dual role. For OLEDs, we focus on solution processing methods to fabricate highly efficient phosphorescent OLEDs. First, we investigated OLEDs with a polymer host matrix, and enhanced charge injection by adding hole- and electron-transport materials into the system. We also applied a hole-blocking and electron-transport material to prevent luminescence quenching by the cathode. Finally, we substituted the polymer host by a small molecule, to achieve more efficient solution processed small molecular OLEDs (SMOLEDs); this approach is cost-effective in comparison to the more common vacuum thermal evaporation. All these studies help us to better understand the underlying relationship between the organic semiconductor materials and the OSCs and OLEDs’ performance and will subsequently assist in further enhancing the efficiencies of OSCs and OLEDs. With better efficiency and longer lifetime, the OSCs and OLEDs will be competitive with their inorganic counterparts.

This thesis describes the study of the development and device physics of organic field-effect transistors and organic light-emitting field-effect transistors. Using chemical and physical properties of organic semiconductors such as light emission, multi-functional devices, or “Active Channel Field-Effect Transistors” can be created. This thesis first describes the creation of basic ambipolar FETs before building on this knowledge to develop ambipolar as well as hole-dominated light emitting field-effect transistors. Ambipolar FETs using a diketopyrrolopyrrole-based copolymer were first investigated in this thesis. When gold electrodes were used, the devices could transport only holes. The charge injection was altered by changing the contacts to aluminium. The devices then were able to conduct both electrons and holes with maximum electron and hole mobilities of order 10−4 cm2 V−1 s−1 and 10−3 cm2 V−1 s−1 respectively. Light-emitting field-effect transistors were first studied using the model emissive polymer Super Yellow. Charge injection was studied by altering the electron-injecting contact. Materials used included the low work function metals Ca, Ba and Sm, the inorganic salt Cs2CO3 and the organic material TPBi. Ambipolar devices were created using a neat Super Yellow layer. Electron and hole mobilities in these devices were both of the order of 10−4 cm2 V−1 s−1. The maximum external quantum efficiency was 1.2 ± 0.2 % with a Sm electron-injecting contact, however this occurred at a brightness of less than 1 cd m−2. A maximum brightness of 43 ± 9 cd m−2 was obtained using a Cs2CO3-Ag electron-injecting contact in electron accumulation mode. At this brightness, the external quantum efficiency was 0.19 ± 0.04 %. Unipolar devices were also fabricated by adding high mobility charge transport layer of PBTTT underneath the Super Yellow. Since PBTTT had a hole mobility that was orders of magnitude greater than the charge carrier mobilities of Super Yellow, charges were transported in the PBTTT, and recombined within the Super Yellow layer. Super Yellow acted as an emissive layer only. Using this bilayer device architecture, a maximum brightness of 100 ± 4 cd m−2 was obtained with a Ca electron-injecting contact. An external quantum efficiency of 0.04 ± 0.01 % was achieved at the maximum brightness. In order to improve the external quantum efficiency of LEFETs, phosphorescent materials were chosen for use as the emissive layer. A co-evaporated layer of the iridium complex Ir(ppy)3 in a host of CBP was initially used in the devices. Charge injection was studied by using either a Ba or a TPBi/Ba electron-injecting contact. Devices were first fabricated using PBTTT as a hole-dominated charge transport layer. Using a TPBi/Ba electron-injecting contact, the maximum brightness achieved was 200 ± 40 cd m−2 with an external quantum efficiency of 0.18 ± 0.01 % at the maximum brightness. Devices were then fabricated using a charge transport layer of DPP-DTT to create ambipolar devices. Electron and hole mobilities in these devices were both of order 10−2 cm2 V−1 s−1. The maximum external quantum efficiency was 0.4 ± 0.2 % at the maximum brightness of 500 ± 200 cd m−2 in hole accumulation mode using an electron-injecting contact of TPBi/Ba. In order to avoid using a co-deposited emissive layer, a solution-processed iridium-cored dendrimer layer that could be deposited without a host material was used. Like in the previous work, a charge transport layer of PBTTT was deposited underneath the emissive layer. Charge injection in the devices was altered using a change in the device geometry. Non-planar source and drain contacts were used, where one contact was deposited directly on top of the charge transport layer and the other contact on top of the emissive layer. Planar contacts were also used as control devices. There was clear evidence for transport of both holes and electrons when planar contacts were used, with light emission occurring at both contacts. The maximum mobility, brightness and external quantum efficiency was achieved using the non-planar contact geometry. Holes could be directly injected into the charge transport layer, rather than via the emissive layer. The hole mobility in these devices was 3.5 × 10−3 ± 6 × 10−4 cm2 V−1 s−1. The maximum brightness was 140 ± 50 cd m−2 with an external quantum efficiency of 0.11 ± 0.02 % at the maximum brightness. This thesis describes work on the study of charge injection into organic field-effect transistors by changing either the material used for the electron-injecting contact, or by changing the device geometry. This was achieved in devices that were either dominated by holes, or showed evidence of both electron and hole transport within the device. By changing the charge injection into the device, it was possible to improve the charge carrier mobilities, the brightness or the external quantum efficiency. Improving one or more of these things brings light emitting transistors towards becoming a viable technology.

All printing of organic photovoltaics (OPVs) including the top electrode is highly desirable for achieving cost‐effective, high‐throughput, and large‐area photovoltaic manufacturing. Here, the printing of a low‐melting‐point alloy as top electrodes in OPVs via blade coating is investigated. The Field's metal (FM) with the melting point of 62 °C is adopted for the top electrodes, because FM can be printed under moderate temperatures without harming the active layers while remaining solid state under solar irradiation. The correlations between the processing parameters and properties of the blade‐coated electrodes are elucidated. OPVs based on the D18:Y6 active layer and blade‐coated FM electrodes achieve a highest power conversion efficiency of 17.28%. The OPVs with FM‐electrode demonstrate much higher thermal stability than that of the Ag‐electrode devices. All‐printed OPVs, in which the FM electrode is blade coated and the other layers are prepared by flexible micro‐comb printing, exhibit an efficiency of 16.07%. The results represent the records of evaporation‐free and all‐printed OPVs, demonstrating that printing FM as OPV electrodes is a cost‐effective and time‐saving strategy to substitute the vacuum‐evaporated metals, as well as a feasible route toward high‐performance all‐printed OPVs.