Solution‐processed organic light‐emitting diodes (OLEDs) with thermally activated delayed fluorescent (TADF) material as emitter have attracted much attention because of their low cost and high performance. However, exciton quench at the interface between the hole injection layer, poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), and emitting layer (EML) in devices can lead to low device performance. Here, a novel high triplet energy (2.89 eV) and crosslinkable hole‐transporting material grafted with oxetane groups, N,N‐bis(4‐(6‐((3‐ethyloxetan‐3‐yl)methoxy)hexyloxy)phenyl)‐3,5‐di(9H‐carbazol‐9‐yl)benzenamine (Oxe‐DCDPA)), as crosslinked hole transport layer (HTL) into the interface of PEDOT:PSS layer and EML is proposed for prevention of exciton quenching, and among the reported devices with single HTL in solution‐processed TADF‐OLED, the highest external quantum efficiency (EQE)/luminous efficiency (ηL) of 26.1%/94.8 cd A−1 and 24.0%/74.0 cd A−1 are achieved for green emission (DACT‐II as emitter) and bluish‐green emission (DMAC‐TRZ as emitter), respectively. Further improvement, using double HTLs, composed of N,N′‐bis(4‐(6‐((3‐ethyloxetan‐3‐yl)methoxy))‐hexylphenyl)‐N,N′‐diphenyl‐4,4′‐diamine with high hole mobility and Oxe‐DCDPA with high triplet energy, leads to the highest EQE/ηL of 30.8%/111.9 cd A−1 and 27.2%/83.8 cd A−1 for green emission and bluish‐green emission, respectively. These two devices show the high maximum brightness of 81 100 and 70 000 cd m−2, respectively.

have received broad research attention as promising candidates for renewableenergy conversion devices owing to their mechanical flexibility, lightweight, absence of toxic heavy metals, and the potential for large-scale fabrication by roll-to-roll printing methodologies. [1] Realization of high-performance BHJ-OSCs devices has relied on photoactive materials design, synthesis, and characterization, as well as thin-film processing advances and device architecture optimization. [2] Since nonfullerene acceptors (NFAs) have now surpassed fullerene acceptors in key properties affecting OSC performance, including strong optical absorption in the visible-near-infrared (vis-NIR) region, adjustable energy levels, charge transport magnitude, and facile structural modification, considerable efforts have been devoted to understanding and perfecting NFAs in recent years. [3] The development of narrow-bandgap (NBG) NFAs with strong optical oscillator strength in the vis-NIR range of 600-1000 nm has been pioneered by several groups; specifically Hou and co-workers reported ITIC-4F [4] and IEICO-4F, [5] and Zhou and co-workers developed Y6. [6] These NFAs when combined with the proper donor polymers have enabled power conversion efficiencies (PCEs) ≈18% for both single-junction and multijunction devices, [7] Fluorination of the donor and/or acceptor blocks of photoactive semiconducting polymers is a leading strategy to enhance organic solar cell (OSC) performance. Here, the effects are investigated in OSCs using fluorine-free (TPD-3) and fluorinated (TPD-3F) donor polymers, paired with the nonfullerene acceptor Y6. Interestingly and unexpectedly, fluorination negatively affects performance, and fluorine-free TPD-3:Y6 OSCs exhibit a far higher power conversion efficiency (PCE = 14.5%) than in the fluorine-containing TPD-3F:Y6 blends (PCE = 11.5%). Transmission electron microscopy (TEM) analysis indicates that the TPD-3F:Y6 blends have larger phase domain sizes than TPD-3:Y6, which reduces exciton dissociation efficiency to 81% for TPD-3F:Y6 versus 93% for TPD-3:Y6. Additionally, grazing incidence wideangle X-ray scattering (GIWAXS) reveals that the TPD-3F:Y6 blends are less textured than those of TPD-3:Y6, while space-charge limited currents reveal lower and unbalanced hole/electron mobility in TPD-3F:Y6 versus TPD-3:Y6 blends. Charge recombination dynamic, transient absorption, and donoracceptor miscibility assays additionally support this picture. Furthermore, conventional architecture TPD-3:Y6 OSCs deliver a PCE of 15.2%, among the highest to date for halogen-free polymer donor OSCs. Finally, a large-area (20.4 cm 2 ) TPD-3:Y6 blend module exhibits an outstanding PCE of 9.31%, one of the highest to date for modules of area >20 cm 2 .

A scalable and accessible photoactive formulation with a low synthetic complexity (SC) index is utilized in organic photovoltaic (OPV) fabrication. The formulation readily dissolves in nonchlorinated solvents, and the corresponding photoactive films can be processed by various coating methods to fabricate devices with power conversion efficiencies (PCEs) of 16.1% and 15.2% when using vacuum‐based molybdenum oxide and solution‐processable conducting polymer as the hole transporting layer in the inverted structure, respectively. This prepared device shows superior stability under light exposure. The PCE is maintained 94% of the initial values after 1080 h of light soaking at 100 mW cm−2. Furthermore, the figure of merit based on the ratio of the SC index and PCE indicates the benefit of this formulation for OPV manufacturing, showing the feasibility of commercialization. Eventually, a PCE of 10.3% is demonstrated for a mini‐module fabricated under ambient conditions, with an active area of 32.6 cm2. To our knowledge, this PCE is one of the largest values reported to date for a green solvent and an all‐solution‐processed OPV module with an inverted architecture.

OPD and readout integrated circuit (ROIC) enables several advantages. [6] For example, the sensor area can potentially reach a larger fill factor as the OPD is directly overlaid on top of an ROIC, which means that more incident photons will be absorbed by the photoactive layer (PAL), leading to imagers that are more sensitive to light. [5] In addition, the response spectra for organic semiconductors can be designed and tuned by adjusting the chemical structure, and the application of organic-based image sensors can be easily extended by changing the PAL materials with various light responses. [7,8] Among image sensors, near infrared (NIR) and shortwave infrared (SWIR) imaging technologies are essential to many applications, including health monitoring, [9,10] machine vision, [11] optical communication, [12] and spectro scopy. [13] Currently, the semiconductors utilized for the detection of NIR radiation are still determined by silicon (Si) technology, [14] such that the sensor structure requires high-temperature growth and complex bonding processes, and at a cost that remains prohibitive for large-area manufacturing. The external quantum efficiencies (EQEs) of Si-based detectors are also intrinsically limited when the incident light extends to the SWIR region, in which the wavelength (λ) is longer than 1000 nm.Considering various breakthroughs during the development of OPDs, it is noted that improvements that result in high performance always rely on both material innovation and stateof-the-art device engineering. An OPD with high EQEs of 66% and 67% at a wavelength of 940 and 1000 nm has been realized recently by using a specifically designed nonfullerene acceptor (NFA). [15] This result indicates the significant future potential of organic image sensor technology. For device engineering, photo multiplication type OPD has been developed successfully for highly sensitive sensors under weak light condition. Photomultiplication effect is commonly obtained by introducing charge traps in photoactive layer of OPD to realize interfacial trap-assisted charge injection, leading to the EQE larger than 100%, and the additional amplification systems are no longer needed due to its high EQE. [16,17] Also, OPD with narrowband spectral response has also been demonstrated by introducing the photomultiplication and charge injection narrowing Near infrared (NIR) and shortwave infrared (SWIR) image technologies are of interest for many emerging applications. Among photodetector technologies, organic photodetectors (OPDs) are groundbreaking light sensors with unique photon-to-electron responses at various wavelengths that offer limitless flexibility in field applications due to the tunable design of organic semiconductors. Herein, a top-illuminated OPD deposited on bottom aluminum electrode with a spectral response beyond a wavelength of 1000 nm is reported, which suggests a feasibility for image sensors integrated with bottom readout circuit. The results reveal that a device composed of aluminum-doped zinc oxide, nickel oxide, and...

We propose the novel σ–π conjugated polymer poly(biphenyl germanium) grafted with two electron‐donating acridan moieties on the Ge atom for use as the host material in a polymer light‐emitting diode (PLED) with the sky‐blue‐emitting thermally activated delayed fluorescence (TADF) material DMAC‐TRZ as the guest. Its high triplet energy (ET) of 2.86 eV is significantly higher than those of conventional π–π conjugated polymers (ET=2.65 eV as the limit) and this guest emitter (ET=2.77 eV). The TADF emitter emits bluer emission than in other host materials owing to the low orientation polarizability of the germanium‐based polymer host. The Ge atom also provides an external heavy‐atom effect, which increases the rate of reverse intersystem crossing in this TADF guest, so that more triplet excitons are harvested for light emission. The sky‐blue TADF electroluminescence with this host/guest pair gave a record‐high external quantum efficiency of 24.1 % at maximum and 22.8 % at 500 cd m−2.