Self-assembled Monolayer Treatment Research Articles

High-Performance Organic Field-Effect Transistors of Liquid Crystalline Organic Semiconductor by Laser Mapping Annealing.

Organic semiconductors (OSCs), especially small molecule semiconductors, have received increasing attention due to their good designability and variability. Phase transitions and interfacial properties have a decisive influence on device performance. Here, 2-Dodecyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-12) devices are treated with low-power laser annealing, which is able to avoid the influence of the dewetting effect on the hole mobility of organic semiconductor materials. Ultraviolet ozone treatment and self-assembled monolayer treatment can improve the performance and stability of the device. Moreover, after low-temperature thermal annealing, the hole mobility of the device can even reach as high as 4.80 cm2 V-1 s-1, and we tested the optical response of the device to the ultraviolet wavelength and found that its maximum optical responsivity was 8.2 AW-1.

Performance enhancement of solution-processed p-type CuI TFTs by self-assembled monolayer treatment

Self-assembled monolayer (SAM) treatment of gate dielectrics plays a key role in the improvement of the electrical performance of organic thin-film transistors (TFTs) by reducing the interface traps. However, it is rarely explored in inorganic TFTs owing to possible irreversible damage to very thin SAMs during the sputtering and high-temperature annealing processes that are often used to deposit inorganic materials. Here, the feasibility of performance enhancement of inorganic p-type Zn-doped CuI TFTs is explored by a SAM treatment using 3-aminopropyltriethoxysilane (APTES) on the gate dielectric. Our result shows that the TFT performance is significantly enhanced with a 50% reduction in the interface trap density, a 326% increase in the hole mobility from 0.38 to 1.24 cm2V-1s-1and a 5-fold increase in the current on/off ratio from 2.6 × 106 to 1.1 × 107. In addition, the bias stress stability of the TFTs after the treatment is dramatically enhanced by a factor of 10 due to the improved interface properties. The threshold voltage shift is reduced from +19.6 to +1.8 V after 3600 s positive bias stress. The simple yet effective interface treatment approach may have great potential in the fabrication of high-performance inorganic p-type electronic devices.

Printed organic Schottky diode with self-assembled monolayer for 13.56 MHz band near-field communication

We demonstrate printed organic Schottky diodes for the rectification of the 13.56 MHz near-field communication carrier wave. Printed silver electrodes covered with a self-assembled monolayer of 4-methylbenzenethiol were employed for the Schottky barrier. Optimizing the conditions of the self-assembled monolayer treatment was performed to improve the rectification ratio to 106 and the forward current density to 1 A cm−2. Finally, organic half-wave and full-wave rectifiers were demonstrated with a high-frequency response of output rectifying voltage of more than 5 V at 13.56 MHz.

(Invited, Digital Presentation) Oxide TFTs Based on Semiconductors and Semimetals

Oxide semiconductors have opened a new era for large-area, flexible and transparent applications. Despite the progresses, a bottleneck issue of oxide thin-film transistors (TFTs) is the instability either under bias stress or when used as a current source. Furthermore, the carrier mobility and current driving capability need to be improved for high-spec displays. It is still hugely challenging to overcome both issues using the conventional device structure and oxide semiconductor materials.Here, we review our recent work on novel oxide TFTs that show a few desirable properties. Rather than using an ohmic metal contact as the source electrode, a high work-function Schottky source contact enables depletion around the TFT source region, which results in intrinsic immunity to the negative bias illumination stress, no obvious short channel effect, and superb current saturation over a wide range of drain voltage1. The flat saturation current gives rise to an extremely high voltage gain reaching 23,000, which is, to the best of our knowledge, the highest gain ever achieved by a solid-state transistor to date. The threshold voltage is also found to remain stable under different drain voltages, in contrast to standard TFTs, which may be useful in larger-area displays where the drain voltages of the drive TFTs can differ2. Furthermore, the depletion provided by the Schottky source electrode allows utilizing semi-metal ITO to replace IGZO as the TFT channel layer, which significantly enhances the carrier mobility and current driving capability. Other related work may also be discussed in the talk including oxide Schottky diodes operating beyond 10 GHz3, oxide TFTs operating beyond 1 GHz4, significantly enhanced carrier mobility by self-assembled monolayer treatment5,6, and CMOS-like oxide-based logic circuits7,8. References Extremely high-gain source-gated transistors, J Zhang, J Wilson, G Auton, Y Wang, M Xu, Q Xin, A Song, Proceedings of the National Academy of Sciences 116 (11), 4843-4848 (2019)Comparative Study of Short-Channel Effects Between Source-Gated Transistors and Standard Thin-Film Transistors, Zhenze Wang, Li Luo, Yiming Wang, Jiawei Zhang, and Aimin Song, IEEE Transactions on Electron Devices, 69(2), 561 - 566 (2022).Flexible indium–gallium–zinc–oxide Schottky diode operating beyond 2.45 GHz, J Zhang, Y Li, B Zhang, H Wang, Q Xin, A Song, Nature communications 6 (1), 1-7 (2015).Amorphous-InGaZnO thin-film transistors operating beyond 1 GHz achieved by optimizing the channel and gate dimensions, Y Wang, J Yang, H Wang, J Zhang, H Li, G Zhu, Y Shi, Y Li, Q Wang, Qian Xin, Zhongchao Fan, Fuhua Yang, Aimin Song, IEEE Transactions on Electron Devices 65 (4), 1377-1382 (2018).Significant Performance Improvement of Oxide Thin‐Film Transistors by a Self‐Assembled Monolayer Treatment, W Cai, J Zhang, J Wilson, J Brownless, S Park, L Majewski, A Song, Advanced Electronic Materials 6 (5), 1901421 (2020).Significant performance enhancement of very thin InGaZnO thin-film transistors by a self-assembled monolayer treatment, W Cai, J Wilson, J Zhang, J Brownless, X Zhang, LA Majewski, A Song, ACS Applied Electronic Materials 2 (1), 301-308 (2020).Complementary integrated circuits based on p-type SnO and n-type IGZO thin-film transistors, Y Li, J Yang, Y Wang, P Ma, Y Yuan, J Zhang, Z Lin, L Zhou, Q Xin, Aimin Song, IEEE Electron Device Letters 39 (2), 208-211 (2017).Thin Film Sequential Circuits: Flip-Flops and a Counter Based on p-SnO and n-InGaZnO, Y Yuan, J Yang, Y Wang, Z Hu, L Zhou, Q Xin, A Song, IEEE Electron Device Letters 42 (1), 62-65 (2020).

Direct self-assembled monolayers treatment on the polar polymer dielectric towards ultra-flexible organic field-effect transistors

• A direct SAM treatment on the polar polymer gate dielectric without any preprocess is introduced. • A hysteresis-free OFET with a high mobility of 1.51 cm 2 V −1 s −1 was achieved. • An ultra-flexible OFET was fabricated and presented a stable electrical performance under deformations. Surface treatment for the polymer gate dielectric plays a significant role in achieving the high-performance flexible field-effect transistors. In this work, the direct SAM treatment on the polar polymer gate dielectric is introduced and the effects on the electrical performance of OFETs are investigated. After an appropriate SAM treatment for the polar polymer dielectric, the mobility can be improved and the hysteresis and interfacial trap states are decreased obviously. Moreover, the SAM treated polymer dielectric is used to achieve the ultra-flexible OFET successfully, with a stable electrical performance under various deformations. These results demonstrate that the direct SAM treatment on polar polymer dielectric is a promising strategy for the high-performance flexible organic transistors, presenting the huge potential for the next-generation flexible electronics.

Gate Dielectric Treated by Self-Assembled Monolayers (SAMs) to Enhance the Performance of InSnZnO Thin-Film Transistors

Self-assembled monolayer (SAM) treatment of gate dielectrics is a standard process for manufacturing organic thin-film transistors (TFTs) to reduce interface trap density and surface energy. However, it is rarely used for oxide semiconductor-based TFTs because the SAMs may be damaged during the manufacturing process. To explore the feasibility of using a SAM-treated gate dielectric to improve the performance of oxide TFTs, we study the effects of different SAM treatments of the gate dielectric layer on the performance of InSnZnO (ITZO) TFTs, which can help guide the selection of SAMs. After treatment with methyltriethoxysilane (C1-SAM), the performance of the TFTs is significantly improved, showing a drastic improvement in the ON/ OFF ratio and carrier mobility, and a reduction of the interface trap density and <inline-formula> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> shift of the device under positive/negative bias stress (PBS/NBS). However, after treatment with n-octyltriethoxysilane (C8-SAM) and octadecyltriethoxysilane (C18-SAM), the performance of the TFTs deteriorate or even fail. Nevertheless, this work demonstrates an effective strategy for the construction of high-performance metal oxide TFTs, though it may require careful selection of the SAMs.

Microscopic observation of efficient intergrain charge transport processes in organic transistors of semicrystalline poly(3-hexylthiophene)

Carrier dynamics in polymer transistors were investigated microscopically using electron spin resonance (ESR) spectroscopy for poly(3-hexylthiophene), a typical semicrystalline conjugated polymer. Charge transport processes across crystalline grains, indispensable for enhancing macroscopic mobility, are highlighted. For this purpose, we used high-molecular-weight (∼500 000) polymers to connect the grains by tie chains. Motional narrowing effects in ESR spectra demonstrated that efficient intergrain charge transport takes place for transistors with self-assembled monolayer (SAM) treatment on SiO2 gate insulators. Meanwhile, transistors without SAMs showed un-narrowed signals, indicating that the surface treatment possibly controls molecular orientations of tie chains more favorable for intergrain charge transport.

Effect of Variations in the Alkyl Chain Lengths of Self-Assembled Monolayers on the Crystalline-Phase-Mediated Electrical Performance of Organic Field-Effect Transistors.

Self-assembled monolayers (SAMs) of organic molecules are frequently employed to improve the electrical performance of organic field-effect transistors (OFETs). However, the relationship between SAM properties and OFET performance has not been fully explored, leading to an incomplete understanding of the system. This study investigates the effect of the SAM alkyl chain length on the crystalline phase of pentacene films and OFET performance. Two types of SAMs—with alkyl chain lengths of 10 (decyltrichlorosilane, DTS) and 22 (docosyltrichlorosilane, DCTS)—were examined, and variations in the performance of pentacene-based OFETs with the nature of the SAM treatment were observed. Despite the similar surface morphologies of the pentacene films, field-effect mobility in the DCTS-treated OFET was twice that in the DTS-treated OFET. To find the reason underlying the dependence of the OFET’s electrical performance on the SAM alkyl chain length, X-ray diffraction measurements were conducted, followed by a phase analysis of the pentacene films. Bulk and thin-film phases were observed to coexist in the pentacene film grown on DTS, indicating several structural defects in the film; this can help explain the dependence of the OFET electrical performance on the SAM alkyl chain length, mediated by the different crystalline phases of pentacene.

Nano Ag sintering on Cu substrate assisted by self-assembled monolayers for high-temperature electronics packaging

Sintering of nano Ag paste on bare Cu has attracted more interests recently for high-temperature electronics packaging, which offers the advantages of high reliability, cost-effective and direct bonding process. However, the current bonding methods normally need a protective atmosphere or metallization on Cu substrate to avoid oxidation. In this study, self-assembled monolayers (SAMs) were deposited on Cu substrate to suppress oxidation prior to nano Ag sintering. Thermal-compression bonding process of Cu/nano Ag/Cu joints was conducted and analysed with and without SAMs treatment. The cross-sectional characterization and shear tests were conducted to evaluate the influence of SAMs treatment. When SAMs applied, shear strength of 12.72 MPa has been achieved in the ambient atmosphere, which is much higher than the value without SAMs treatment (3.77 MPa). It has been identified that the shear mode changed from the interfaces of sintered nano Ag/Cu to inside of sintered nano Ag due to the applied SAMs. This technological approach provides a tangible and cost-effective method for high-temperature electronics packaging.

Comparison of self-assembled monolayers with long alkyl chains on ITO for enhanced surface properties and photovoltaic performance

Self-assembled monolayers (SAMs) are used as interfacial layer up to a few nanometer thick in electronic devices to tune the morphological and charge transport properties. Herein, we studied indium titanium oxide (ITO) treatment by two different SAMs molecules involving long alkyl chains with boronic acid (BA) and phosphonic acid anchoring groups to improve the performance of organic solar cells (OSCS). It was determined that the wettability of ITO increased due to the improved surface energy after SAM treatment, which led to enhanced morphology of upper layer. The champion device treated with C14-BA SAM showed a power conversion efficiency (PCE) of 3.3%, which is higher than that of non-treated device (2.9%). The C14-BA SAM treated ITO showed a better morphology and its device shows the highest performance, thanks to improved short circuit current (Jsc) from 7.8 mA cm−2 (for non-treated device) to 8.8 mA cm−2. It was concluded that the work function change and upper layer morphology can be easily controlled by treatment of the ITO surface by SAMs with different anchoring groups. This study provides an easy and alternative approach to enhance the surface properties of metal oxides for improving the performances of OSCs.

Surface Energy Characterized Self-Assembled Monolayer for Improving Electrical Stability of IGZO Thin Film Transistor

The surface energy characterized self-assembled monolayer (SAM) for improving the electrical stability of Indium gallium zinc oxide (IGZO) semiconductor is proposed. In order to compare properly, the head group and body group were fixed with silane and alkyl chains, respectively, and only the functional group was changed, NH2, CH3, CF3 respectively. The surface energies of NH2, CH3 and CF3 functional group SAMs were measured as 50 mJ/m2, 29 mJ/m2 and 24 mJ/m2, respectively by Owens-Wendt model with the contact angle values. The SAM treatment for IGZO TFT backchannel passivation amazingly improves the positive bias stability (PBS) and clockwise hysteresis stability to the very similar tendency by making oxygen-related molecules difficult to be adsorbed onto IGZO backchannel depending on the surface energies of SAMs. In case of NH2 SAM treated IGZO TFT, the PBS improvement ratio by the treatment was 78.7 % (from 11.6 V to 2.5 V) and the clockwise hysteresis improvement ratio was 70.5 % (from 0.8 V to 0.2 V). Furthermore, it was confirmed that the better result was obtained at a lower surface energy functional group. The IGZO TFT PBS further improved 87.0 % after the lowest surface energy with CF3 SAM treatment (from 2.5 V to 0.3 V), and the IGZO TFT clockwise hysteresis was also further enhanced 52.2 % (from 0.2 V to 0.1 V) without any deterioration of TFT characteristics. The field-effect mobility and sub-threshold swing of the IGZO reference TFT with non-SAM treated were 11.2 cm2 / Vs and 0.2 V / decade, respectively. NH2, CH3, and CF3 functional group SAM treated IGZO TFTs show the field-effect mobility of 13.5 cm2 / Vs, 13.0 cm2 / Vs, 13.1 cm2 / Vs, and sub-threshold swing of 0.18 V / decade, 0.20 V / decade, 0.18 V / decade, respectively. As a result, the simple and economical SAM treatment with lower surface energy functional group surface at same head and body group can be a better way in passivating and protecting the IGZO backchannel region from oxygen molecules in the atmosphere in order to enhance the electrical stability of IGZO TFT. Figure 1

Electrode and dielectric layer interface device engineering study using furan flanked diketopyrrolopyrrole\u2013dithienothiophene polymer based organic transistors

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 effect of surface energy characterized functional groups of self-assembled monolayers for enhancing the electrical stability of oxide semiconductor thin film transistors

The exact direction of the surface energy characterized functional groups of self-assembled monolayers (SAMs) is proposed for achieving enhanced electrical stability of indium gallium zinc oxide (IGZO) semiconductor thin film transistors (TFTs). The SAM treatment, particularly with the SAM functional group having lower surface energy, makes it difficult to adsorb oxygen molecules difficult onto IGZO. Such an effect greatly improves the positive bias stability (PBS) and clockwise hysteresis stability. For NH2 and CF3 functional groups, SAMs with surface energies of 49.4 mJ m−2 and 23.5 mJ m−2, respectively, improved the IGZO TFT PBS from 2.47 V to 0.32 V after the SAM treatment and the IGZO TFT clockwise hysteresis was also enhanced from 0.23 V to 0.11 V without any deterioration of TFT characteristics. Employing lower surface energy functional groups to the SAM, of the same head and body groups, passivates and protects the IGZO backchannel region from oxygen molecules in the atmosphere. Consequently, the enhanced electrical stability of IGZO TFTs can be achieved by the simple and economic SAM treatment.

Significant Performance Enhancement of Very Thin InGaZnO Thin-Film Transistors by a Self-Assembled Monolayer Treatment

The use of amorphous InGaZnO (IGZO) has become more and more popular especially in display technologies because of its high mobility, excellent large area uniformity, and low-temperature processabi...

One-Volt, Solution-Processed Organic Transistors with Self-Assembled Monolayer-Ta2O5 Gate Dielectrics.

Low-voltage, solution-processed organic thin-film transistors (OTFTs) have tremendous potential to be key components in low-cost, flexible and large-area electronics. However, for these devices to operate at low voltage, robust and high capacitance gate dielectrics are urgently needed. Herein, the fabrication of OTFTs that operate at 1 V is reported. These devices comprise a solution-processed, self-assembled monolayer (SAM) modified tantalum pentoxide (Ta2O5) as the gate dielectric. The morphology and dielectric properties of the anodized Ta2O5 films with and without n-octadecyltrichlorosilane (OTS) SAM treatment have been studied. The thickness of the Ta2O5 film was optimized by varying the anodization voltage. The results show that organic TFTs gated with OTS-modified tantalum pentoxide anodized at 3 V (d ~7 nm) exhibit the best performance. The devices operate at 1 V with a saturation field-effect mobility larger than 0.2 cm2 V−1 s−1, threshold voltage −0.55 V, subthreshold swing 120 mV/dec, and current on/off ratio in excess of 5 × 103. As a result, the demonstrated OTFTs display a promising performance for applications in low-voltage, portable electronics.

An Easy Route to Wettability Changes of Polyethylene Terephthalate⁻Silicon Oxide Substrate Films for High Barrier Applications, Surface-Modified with a Self-Assembled Monolayer of Fluoroalkylsilanes.

Inorganic–organic multilayer films consisting of polymers coated with thin inorganic oxidic layers (e.g., SiOx) ensure very high barrier performances against gas and vapor permeation, what makes them packaging materials suitable for sophisticated technical applications, including the encapsulation of photovoltaic devices or quantum dots, barrier films for optical displays, and transparent greenhouse screens. In these fields, surface coating or texturing of the multilayer protective films are effective technologies to improve their self-clean ability, thus reducing the required maintenance and ensuring longer durability and better performances. In this work, we used the self-assembled monolayer (SAM) technique to modify the surface and wetting properties of commercial polyethylene terephthalate-silicon oxide substrate (PET-SiOx) films developed for technical applications requiring a combined high barrier and transparency. The selected surface modifier was the 1H,1H,2H,2H-per-fluorodecyltrichlorosilane (FDTS). The reagent mixture composition was optimized for the lowest water and oil wettability, as well as the highest self-cleaning capacity and performance stability. In particular, for the used PET-SiOx film the best FDTS/film surface for both the lowest water and oil wettability was found to be equal to 26.5 mM/dm2, which changes the surface behavior from very hydrophilic (static water contact angle (CAw) = 21.5°) to hydrophobic (CAw = 101°), and gives a significant increment of the static oil contact angle (CAo) from 27° to 60°. Interestingly, the results demonstrated that the SAM reaction occurred also on the uncoated the PET side. After the SAM treatment, a small increase of the water vapor permeability is observed, probably due to a crack or defect onset of the SiOx coating of the SAM modified films. On this point, atomic force measurements demonstrated an increment of the SiOx coating layer roughness after the SAM treatment execution. Finally, the transparency changes of the SAM treated films, measured in the wavelength range 400–800 nm, were always small, so that the results were acceptable for the films’ use in applications where high transparency is required.

Threshold Voltage Control of Multilayered MoS2 Field-Effect Transistors via Octadecyltrichlorosilane and their Applications to Active Matrixed Quantum Dot Displays Driven by Enhancement-Mode Logic Gates.

In recent past, for next-generation device opportunities such as sub-10 nm channel field-effect transistors (FETs), tunneling FETs, and high-end display backplanes, tremendous research on multilayered molybdenum disulfide (MoS2 ) among transition metal dichalcogenides has been actively performed. However, nonavailability on a matured threshold voltage control scheme, like a substitutional doping in Si technology, has been plagued for the prosperity of 2D materials in electronics. Herein, an adjustment scheme for threshold voltage of MoS2 FETs by using self-assembled monolayer treatment via octadecyltrichlorosilane is proposed and demonstrated to show MoS2 FETs in an enhancement mode with preservation of electrical parameters such as field-effect mobility, subthreshold swing, and current on-off ratio. Furthermore, the mechanisms for threshold voltage adjustment are systematically studied by using atomic force microscopy, Raman, temperature-dependent electrical characterization, etc. For validation of effects of threshold voltage engineering on MoS2 FETs, full swing inverters, comprising enhancement mode drivers and depletion mode loads are perfectly demonstrated with a maximum gain of 18.2 and a noise margin of ≈45% of 1/2 VDD . More impressively, quantum dot light-emitting diodes, driven by enhancement mode MoS2 FETs, stably demonstrate 120 cd m-2 at the gate-to-source voltage of 5 V, exhibiting promising opportunities for future display application.

Ultrahigh Conductivity and Superior Interfacial Adhesion of a Nanostructured, Photonic-Sintered Copper Membrane for Printed Flexible Hybrid Electronics.

Inkjet-printed electronics using metal particles typically lack electrical conductivity and interfacial adhesion with an underlying substrate. To address the inherent issues of printed materials, this Research Article introduces advanced materials and processing methodologies. Enhanced adhesion of the inkjet-printed copper (Cu) on a flexible polyimide film is achieved by using a new surface modification technique, a nanostructured self-assembled monolayer (SAM) of (3-mercaptopropyl)trimethoxysilane. A standardized adhesion test reveals the superior adhesion strength (1192.27 N/m) of printed Cu on the polymer film, while maintaining extreme mechanical flexibility proven by 100 000 bending cycles. In addition to the increased adhesion, the nanostructured SAM treatment on printed Cu prevents formation of native oxide layers. The combination of the newly synthesized Cu ink and associated sintering technique with an intense pulsed ultraviolet and visible light absorption enables ultrahigh conductivity of printed Cu (2.3 × 10-6 Ω·cm), which is the highest electrical conductivity reported to date. The comprehensive materials engineering technologies offer highly reliable printing of Cu patterns for immediate use in wearable flexible hybrid electronics. In vivo demonstration of printed, skin-conformal Cu electrodes indicates a very low skin-electrode impedance (<50 kΩ) without a conductive gel and successfully measures three types of biopotentials, including electrocardiograms, electromyograms, and electrooculograms.

Enhanced performance of inverted non-fullerene organic solar cells through modifying zinc oxide surface with self-assembled monolayers

Abstract Non-fullerene organic solar cells (OSCs) have attracted great attention due to their advantages such as tunable energy levels, reduced energy loss, strong light absorption. Here, three small molecules with polar functional groups were utilized to modify the surface of zinc oxide (ZnO) electron transport layer through self-assembled monolayers (SAMs) formation. Inverted non-fullerene OSCs with PBDB-T:ITIC blend as active layer based on the ZnO with SAMs modification showed enhanced device performance (10.90%) compared to that without SAM treatment (10.03%). The ultraviolet photoelectron spectroscopy results revealed that the SAMs could lower the surface work function of ZnO, allowing for better electron extraction. The analysis results of J-V characteristics under different light illumination intensities suggested more efficient charge dissociation and weaker trap-assisted bimolecular recombination in the devices with SAMs modification. Our work provides an effective approach to modify the ZnO surface for efficient non-fullerene OSCs.

Enhanced Device Efficiency and Long-Term Stability via Boronic Acid-Based Self-Assembled Monolayer Modification of Indium Tin Oxide in a Planar Perovskite Solar Cell

Interfacial engineering is essential for the development of highly efficient and stable solar cells through minimizing energetic losses at interfaces. Self-assembled monolayers (SAMs) have been shown as a handle to tune the work function (WF) of indium tin oxide (ITO), improving photovoltaic cell performance and device stability. In this study, we utilize a new class of boronic acid-based fluorine-terminated SAMs to modify ITO surfaces in planar perovskite solar cells. The SAM treatment demonstrates an increase of the WF of ITO, an enhancement of the short-circuit current, and a passivation of trap states at the ITO/[poly(3,4ethylenedioxylenethiophene):poly(styrenesulfonic acid)] interface. Device stability improves upon SAM modification, with efficiency decreasing only 20% after one month. Our work highlights a simple treatment route to achieve hysteresis-free, reproducible, stable, and highly efficient (16%) planar perovskite solar cells.