Long exciton diffusion length (L-D) is key to maximizing excitation harvesting in organic solar cells, but contradicting values are reported for non-fullerene acceptors (NFA). To understand the factors enabling large L-D, experimental observation of exciton decay by transient absorption spectroscopy (TAS) is combined with microscopic Kinetic Monte Carlo (KMC) simulations on 4 ITIC derivatives. Exciton decays are fitted considering singlet exciton-singlet exciton annihilation (SSA) and the intrinsic exciton's lifetime tau, resulting in L-D from 20 to 70 nm. The critical importance of an independent estimate of tau is discussed and its measurements from pristine NFA films is found to be more relevant than from NFA molecules embedded in an inert polystyrene matrix. From experimental parameters, the microscopic F & ouml;rster Resonant Energy Transfer hopping rate and the annihilation rate in a cubic lattice are determined, considering a Gaussian energetic disorder. KMC simulation of those rates are able to reproduce the experimental transients and L-D,L- provided a lattice constant a close to the molecular pi-pi stacking distance is used. It is found that this tight packing and a low disorder are critical to reach large L-D, and empirically relate linearly such that 40 meV more disorder can be compensated by 1 Angstrom tighter packing (shorter a).

The development of low-power computing sectors requires compact, power-efficient and high-performance integrated circuits. Hybrid technology that combines n-type metal oxide thin-film transistors and p-type organic thin-film transistors offers a potential solution. However, increasing the transistor density of these systems through vertical stacking is challenging due to issues related to thermal budget and interface roughness. Here we report a six-stack hybrid complementary transistor technology that has 41 layers and uses n-type indium oxide (In2O3) and a p-type organic semiconductor (C16IDT-BT) as channel materials. We test 600 transistors and show that n-type oxide devices and p-type organic devices exhibit comparable field-effect mobilities and saturation currents. We also create 300 hybrid inverters by integrating the oxide and organic transistors; the circuits exhibit a gain of 94.84 V V−1 and a power consumption of 0.47 µW. We also fabricate NAND and NOR gates comprising transistors from four stacks. Thermal stability analysis shows that device characteristics begin to degrade above 50 °C, a known limitation of low-thermal-budget processes. Such performance is sufficient for many large-area electronics applications, but further thermal optimization will be necessary to extend operational robustness towards standard industrial conditions. A six-stack hybrid complementary transistor technology that uses n-type indium oxide and a p-type organic semiconductor as channel materials can be used to build inverters that exhibit a gain of 94.84 V V−1 and a power consumption of 0.47 µW.

As human-machine interface hardware advances, better sensors are required to detect signals from different stimuli. Among numerous technologies, humidity sensors are critical for applications across different sectors, including environmental monitoring, food production, agriculture, and healthcare. Current humidity sensors rely on materials that absorb moisture, which can take some time to equilibrate with the surrounding environment, thus slowing their temporal response and limiting their applications. Here, this challenge is tackled by combining a nanogap electrode (NGE) architecture with chicked egg-derived albumen as the moisture-absorbing component. The sensors offer inexpensive manufacturing, high responsivity, ultra-fast response, and selectivity to humidity within a relative humidity range of 10-70% RH. Specifically, the egg albumen-based sensor showed negligible response to relevant interfering species and remained specific to water moisture with a room-temperature responsivity of 1.15 × 104. The nm-short interelectrode distance (circa 20 nm) of the NGE architecture enables fast temporal response, with rise/fall times of 10/28 ms, respectively, making the devices the fastest humidity sensors reported to date based on a biomaterial. By leveraging these features, non-contact moisture sensing and real-time respiratory cycle monitoring suitable for diagnosing chronic diseases such as sleep apnea, asthma, and pulmonary disease are demonstrated.

We report a series of n-type conjugated polymers based on PNDI-TfBTT and PNDIV-TfBTT backbones constructed from electron-deficient naphthalene diimide (NDI) and fluorinated benzothiadiazole (fBT) units, with PNDIV-TfBTT incorporating a vinylene spacer. Quantitative postpolymerization modification (PPM) via nucleophilic substitution replaced the fBT fluorine with thioether side chains, optionally containing azide groups. Thioether substitution improved solubility, while subtly changing the ordering of polymer films. Azide incorporation enabled both thermal and photochemical crosslinking, yielding insoluble and immobile films that retained good electron transport; although UV crosslinking initially reduced mobility, subsequent thermal annealing largely restored crystallinity and performance. This work underscores the utility of precise backbone editing to fine-tune the electronic and morphological properties of n-type polymers, offering new avenues for the fabrication of stable, patterned active layers in advanced organic electronic devices.

Surface modification of transparent conductive oxides (TCOs) with carbazole-based self-assembled monolayers (SAMs) is an effective method toward the formation of highly efficient hole-selective contacts, enabling the fabrication of high-performance perovskite solar cells (PSCs). However, the lack of long-term structural and performance stability of the TCO/SAM/perovskite stack endangers the market entry of PSCs. Here, it is demonstrated that these challenges can be overcome by employing dyes as multi-functional SAMs, simultaneously facilitating charge transport, passivating interfacial defects, and acting as a "molecular adhesive" layer, preserving structural integrity of the contact stack. Particularly, the surface modification of ITO with a dye (N719) monolayer is shown to create a hole-selective contact for the fabrication of p-i-n PSCs with power conversion efficiencies reaching 24%. The N719 SAM-based PSCs have also shown superior stability compared to state-of-the-art PSCs incorporating carbazole SAMs and polyarylamine hole-selective contacts by preserving approximate to 90% of their initial PCE under continuous light and thermal stress tests for 1000 h. The robustness of the ITO/N719/perovskite stack is attributed to its low interfacial trap density, UV resilience and strong adhesion capability. These findings place dye SAMs as a promising alternative for improving the performance of next-generation photovoltaics.

Solution‐based methods have emerged as a promising approach for large‐scale and low‐cost electronics fabrication. However, solution processing has rarely realized high‐performance p ‐type transistors, impeding the advancement of solution‐processed electronics. Among the various solution‐processable material families, van der Waals (vdW) systems stand out due to several attractive features, one of which is the atomically defined interfaces that facilitate carrier charge transport, enabling enhanced device performance. Here, the preparation of transistors based on single tellurium (Te) nanowires (NW) is demonstrated, achieving high mobilities averaging ≈370 cm 2 V −1 s −1 . Notably, subsequent studies reveal that devices based on Te‐Te NW junctions exhibit mobilities comparable to those of the individual NWs forming the junction. This indicates that the vdW contact between the Te NWs causes negligible degradation in the mobility, which aligns with the theoretical calculations. Based on this finding, a large‐area 1D Te NWs vdW film is further prepared, consisting of a large number of 1D Te NWs interconnected by vdW junctions. The resulting transistors can still maintain remarkable operating characteristics, including an average field‐effect hole mobility of ≈94.9 cm 2 V −1 s −1 , a subthreshold swing of ≈248.6 mVdec −1 , a current on/off ratio of ≈10 4 , and a low operating voltage of 1 V.

Narrowband infrared organic photodetectors are in great demand for sensing, imaging, and spectroscopy applications, in particular for handheld and wearable devices, in which miniaturization is essential. However, most existing strategies for narrowband detection depend on spectral filtering either through saturable absorption, which requires active layers exceeding 500 nm, restricting the choice of materials for producing high-quality films, or cavity effects, which inherently introduce strong angular dispersion. Microcavity exciton-polariton (polariton) modes, which emerge from strong exciton-photon coupling, have recently been explored as an angular dispersion suppression strategy for organic optoelectronics. In this work, the first narrowband infrared polariton organic photodiode that combines angle-independent response with a record-high responsivity of 0.24 A W-1 at 965 nm and -2 V is presented. This device, featuring a 100-nm-thin active layer comprising a non-fullerene acceptor, exhibits a detection mode with a full-width at half-maximum of less than 30 nm and a marginal angular dispersion of under 15 nm across +/- 45 degrees. This study highlights the potential of polaritons as an innovative platform for developing next-generation optoelectronic devices that achieve simultaneous enhancements in optical and electronic performance.

Hybrid molecular ferroelectrics necessitate switchable components, either organic or inorganic, capable of altering polarity under a reversing electric field. Isothiocyanate (NCS-) ligands display such behavior through nonlinear coordination with metal ions. Homoleptic complexes of lanthanide ions exhibit variable coordination numbers, which can be controlled by the size of the counterions. We harnessed these properties to achieve polar order and ferroelectricity in hybrid [Er(III)(NCS) x ]3-x complexes. The incorporation of triethyl methylammonium (TEMA) cations yields the complex [TEMA] 4 [Er(NCS) 7 ], which exhibits polarity at low temperatures with a Curie temperature (T c) of 203 K. Notably, the use of bulkier and more rigid ethyltriphenyl phosphonium (ETPP) cations gave a room-temperature stable ferroelectric complex [ETPP] 3 [Er(NCS) 6 ]. In contrast, flexible cations, such as tripropylmethylammonium (TPMA), tributylmethylammonium (TBMA), and tetraethyl phosphonium (TEP) ions, yielded only centrosymmetric complexes. The polar structural symmetries in [TEMA] 4 [Er(NCS) 7 ] and [ETPP] 3 [Er(NCS) 6 ] are attributed to pronounced distortions of the Er(III)-NCS coordination, driven by the rigid nature of organic counterions. The ferroelectric measurements on [ETPP] 3 [Er(NCS) 6 ] gave a saturation polarization (P s) of 1.6 mu C cm-2. Remarkably, [ETPP] 3 [Er(NCS) 6 ] exhibits a high piezoelectric charge coefficient (d 33) of 22.7 pCN-1 and an electrostrictive coefficient (Q 33) of 4.11 m4C-2, enabling its application for piezoelectric energy harvesting.

Ferroelectric materials have emerged as promising candidates for piezoelectric nanogenerators, attributed to their superior energy conversion efficiency derived from inherent polarization characteristics. Polar metal-ligand assemblies represent advantageous alternatives to conventional inorganic ceramics and organic polymers, offering tunable electronic properties, environmental benignity, and enhanced energy conversion capabilities. We demonstrate an octahedral [[Co6(H2O)12(TPTA)8](NO3)1250H2O] cage assembly exhibiting pronounced ferroelectric behavior, characterized by a P-E hysteresis loop with a remnant polarization of 6.84 mu C cm-2. The ferroelectric and piezoelectric properties of 1 were unambiguously confirmed through the visualization of electrical domains in single crystals and crystalline thin films via piezoresponse force microscopy (PFM). Single-point, bias-dependent PFM spectroscopy measurements revealed characteristic amplitude-butterfly and phase-hysteresis loops, substantiating the piezoelectric nature of the material. Piezoelectric energy harvesting investigations conducted on polydimethylsiloxane (PDMS) composite materials revealed a maximum peak output voltage of 12.20 V and a power density of 14.85 mu W cm-2 for the optimized 20 wt % 1-PDMS composite device. The practical utility was validated through the implementation of a smart pressure sensor, wherein a mat device, constructed from five parallel-connected independent devices, successfully functioned as a sensor capable of illuminating a commercial LED under gentle mechanical stimulation. These findings establish the potential of this cage system for integration into self-powered sensor technologies.

Within multijunction organic and hybrid photodetectors (PDs), organic and hybrid phototransistors (HPTs) hold promises for high sensitivity (S) and specific detectivity (D*). However, it is difficult to achieve a trade‐off between a large sensing area, a fast response, and a high D*. Here, we propose an alternative phototransistor concept relying on a geometrically engineered tri‐channel (Tr‐iC) architecture with a 4‐mm 2 large sensing area, applied to a multilayer HPT whose active region is comprised of an inorganic In 2 O 3 /ZnO n‐type field‐effect channel and solution‐processed organic bulk heterojunction (BHJ) or hybrid perovskite light‐sensing layer. The resulting HPTs combine a responsivity (R) up to 10 5 A/W, thanks to the efficient charge transport (at the bottom In 2 O 3 /ZnO layer) and a D* estimated at 10 15 Jones, which allows to measure low light power densities down to 10 nW cm −2 . These figures of merit are coupled to a fast response (risetime <10 ms and falltime of ≈100 ms for illumination, in the µW/cm 2 range), which is comparable to the time‐response of organic PDs in a diode architecture. The experimental data are supported by a comprehensive device modeling, which helps highlighting the peculiar advantages of the proposed large area, Tr‐iC, and multilayer HPT architecture.

The development of non-fullerene acceptor (NFA) based organic solar cells (OSCs) featuring self-assembled monolayers (SAMs) as the transparent hole extraction layers (HELs) has led to power conversion efficiency (PCE) values of over 20%. Unfortunately, SAM-based OSCs exhibit limited operational stability due to their sensitivity to elevated temperature and light stress. Here, we tackled this issue by developing NFA-based OSCs using ultrathin solution-processed molybdenum oxide (s-MoOx) as the HEL. Devices featuring s-MoOx exhibited superior stability while retaining a similar PCE to 2PACz-based cells (similar to 17.3%). The time required for the initial PCE of cells based on ITO/2PACz and the ITO/s-MoOx to degrade by 20% (T80) under continuous thermal stress at 85 degrees C in nitrogen was 15 and 600 h, respectively, highlighting the crucial role of HELs in operational stability. Analysis using time-of-flight secondary ion mass spectroscopy (ToF-SIMS) reveals that in cells with ITO/SAM, the diffusion of electrode elements and 2PACz and chemical interactions with the NFA are responsible for the performance degradation observed. Replacing 2PACz with s-MoOx significantly suppressed the diffusion of ITO and prevented its interaction with the organic semiconductor. Our work revealed the crucial roles of HELs and could help in developing efficient and more stable OSCs.

Hydrogen is an abundant and clean energy source that could help to decarbonize difficult-to-electrify economic sectors. However, its safe deployment relies on the availability of cost-effective hydrogen detection technologies. We describe a hydrogen sensor that uses an organic semiconductor as the active layer. It can operate over a wide temperature and humidity range. Ambient oxygen p-dopes the organic semiconductor, which improves hole transport, and the presence of hydrogen reverses this doping process, leading to a drop in current and enabling reliable and rapid hydrogen detection. The sensor exhibits a high responsivity (more than 10,000), fast response time (less than 1 s), low limit of detection (around 192 ppb) and low power consumption (less than 2 μW). It can operate continuously for more than 646 days in ambient air at room temperature. We show that the sensor outperforms a commercial hydrogen detector in realistic sensing scenarios, illustrating its suitability for application in distributed sensor networks for early warning of hydrogen leaks and preventing explosions or fires. A hydrogen sensor that uses an organic semiconductor as the active layer can offer a high responsivity, fast response time, low limit of detection and low power consumption, and can operate continuously for more than 646 days in ambient air at room temperature.

The self-aligned gate (SAG) transistor architecture is attractive for electronic circuit applications due to its enabling attributes, including low parasitic capacitances and higher frequency operation. However, SAG transistors often rely on complex manufacturing, which limits their practical utilization. Herein, we overcome this bottleneck and demonstrate organic SAG transistors in which the self-aligned source/drain (S/D) electrodes are separated by the gate (G) terminal with sub-20 nm gaps. The SAG architecture eliminates parasitic overlaps while minimizing access resistance for the injected carriers. Moreover, precise work function engineering of the self-aligned Au S/D contacts is demonstrated using phosphonic acid (PA) self-assembled monolayers (SAMs) functionalized directly onto Au. Analysis of the Au surface corroborated by Density Functional Theory calculations and scanning tunneling microscopy reveal the unexpected formation of PA SAMs directly onto Au for the first time. Combining different organic semiconductors with appropriate SAMs enables the development of hole and electron-transporting SAG transistors with enhanced performance. Integrating the n- and p-channel transistors yields complementary logic circuitry with high gain and noise margins, showcasing the effectiveness of this approach. The work highlights the enormous potential of combining the SAG transistor platform with work function modifying PA SAMs to develop printed electronics with improved functionality.

We report three novel donor-acceptor (D-A) copolymers sharing a common fused donor unit (CDTT) but differing in the functionalization of the benzothiadiazole (BT) acceptor unit. Acceptors bearing two cyano groups (DCNBT) are compared to novel acceptors bearing one cyano and one fluorine group (FCNBT) or one nitro and one fluoro group (NO2FBT). The choice of the acceptor has a significant effect on the optoelectronic properties of the resulting polymers. In organic field-effect transistor (OFET) devices, PCDTT-DCNBT exhibited moderate performance with an electron mobility of 0.031 cm2 V-1 s-1, whereas PCDTT-FCNBT demonstrated significantly improved electron mobility (0.4 cm2 V-1 s-1). The improved performance is attributed to increased backbone linearity combined with a more coplanar backbone and high thin-film crystallinity. In comparison, the presence of the nitro group is shown to have a detrimental impact, with a blue-shifted absorption and a 0.2 eV increase in band gap compared to the cyanated polymers. Steric effects are shown to limit the nitro group's π-accepting capability and result in reduced device performance, with an electron mobility of 0.024 cm2 V-1 s-1. This study introduces a new BT building block and highlights that substituent tuning via cyano and fluorine groups is an effective approach for modulating polymer morphology and electron transport.

Self-assembled monolayers (SAMs) help improve the performance of organic electronic devices through interface passivation and enhanced carrier transport. Yet, there is limited information regarding the chemical structure of the SAMs upon functionalization and subsequent thermal treatment. Here, we studied the on-surface reaction of carbazole-derived SAMs on model gold electrodes, focusing on the chemical structure changes induced by thermal treatments. Furthermore, we correlate the microscopic changes with their impact on the electrode's work function. The carbazole-based SAMs first transform into organometallic complexes. At higher annealing temperatures, SAMs convert to oligomeric complexes. The observed chemical reactions significantly reduce the electrode work function and facilitate electron injection in n-type organic thin-film transistors. Our results highlight the on-surface synthesis of electronically active SAMs as an alternative approach for modifying the work function of electrodes for organic electronics.

Modern telecommunication technologies, such as the 5G and upcoming 6G networks, rely on devices operating in the radio frequency (RF) spectrum of 0.3-90 GHz and 7-300 GHz, respectively. To meet these demanding frequency requirements, new manufacturing methods and device architectures are gaining increasing attention. However, achieving scalable manufacturing alongside ultra-fast device operation presents formidable techno-economic challenges. Here, we explored a modified version of adhesion lithography (a-Lith) to create coplanar nanogap zinc oxide (ZnO) Schottky diodes for application in diode-logic arithmetic circuits. The planar ZnO diodes offer highly scalable manufacturing and combine high current rectification (> 106) with low reverse currents (≈80 pA) and a remarkable cut-off frequency of over 25 GHz. Engineering the topologies of the planar ZnO diodes enables their facile monolithic integration into multi-bit AND and OR gates over 4-inch glass wafers. By integrating several such logic gates, we demonstrated fully functional monolithic 2-bit Half-Adder circuits, the primary component of an arithmetic logic unit. The work offers an alternative method for developing fast large-area electronics that could lead to a new family of logic circuitry.

Photonic memristors based on two-dimensional materials are emerging as critical components for ultrascalable, energy-efficient artificial vision systems, integrating opto-sensing, data storage and processing capabilities. However, existing devices typically exhibit narrow spectral response ranges and operate in a single mode (for example, non-volatility), limiting their applications in complex computing scenarios. Here we introduce photonic memristor arrays based on a wafer-scale hexagonal boron nitride (hBN)/silicon (Si) heterostructure. These memristors are developed via in situ, low-temperature (250 °C), large-area growth of highly homogeneous hBN films on Si-based substrates. The devices exhibit opto-reconfigurability across a broad spectral range from ultraviolet to near infrared. By adjusting the incident laser power, the device can be reconfigured between non-resistive-switching, volatile and non-volatile modes. This light-induced reconfigurability is attributed to the formation of conductive filaments through interactions between hydrogen ions and photogenerated electrons within the engineered hBN/Si heterostructures. Furthermore, the photonic memristor features a switching ratio exceeding 109, retention time surpassing 40,000 s, endurance over 106 cycles and thermal stability up to 300 °C. These findings provide a scalable solution for developing integrated sensing-storage-computation artificial vision systems, fully compatible with sophisticated Si-based semiconductor technologies.

A deep understanding of how solution-processed solar cells (SSCs) perform under varying temperatures and irradiance is crucial for their optimal design, synthesis, and use. However, current partial spectral characterization, primarily below the band gap wavelengths (λ < λg), limits insights into their full operation. In this work, we expand the current knowledge by providing comprehensive full-spectrum experimental optical characterizations (∼300-2500 nm) and theoretical optical-thermal-electrical analysis for the most common high-efficiency single-junction and tandem organic SSCs (OSCs) and perovskite SSCs (PSCs), including p-i-n OSC, n-i-p OSC, p-i-n PSC, n-i-p mesoscopic PSC, OSC/PSC, and PSC/PSC. By incorporating solar photons above λg in our investigation, we uncover the effects of parasitic absorption (∼300-2500 nm) and conversion losses (λ < λg) on operating temperature and power conversion efficiency (PCE) losses, highlighting the conditions, materials, and optimal architectures for reducing device temperature. These improvements could reduce PCE losses by up to ∼7 times compared to conventional silicon wafer-based solar cells in real-world conditions.