Highly responsive organic image sensors are crucial for medical imaging applications. To enhance the pixelwise photoresponse in an organic image sensor, the integration of an organic photodetector ...with amplifiers, or the use of a highly responsive organic photodetector without an additional amplifying component, is required. The use of vertically stacked, two‐terminal organic photodetectors with photomultiplication is a promising approach for highly responsive organic image sensors owing to their simple two‐terminal structure and intrinsically large responsivity. However, there are no demonstrations of an imaging sensor array using organic photomultiplication photodetectors. The main obstacle to a sensor array is the weak‐light sensitivity, which is limited by a relatively large dark current. Herein, a highly responsive organic image sensor based on monolithic, vertically stacked two‐terminal pixels is presented. This is achieved using pixels of a vertically stacked diode‐type organic photodetector with photomultiplication. Furthermore, applying an optimized injection electrode and additionally stacked rectifying layers, this two‐terminal device simultaneously demonstrates a high responsivity (>40 A W−1), low dark current, and high rectification under illumination. An organic image sensor based on this device with an extremely simple architecture exhibits a high pixel photoresponse, demonstrating a weak‐light imaging capability even at 1 µW cm−2.
A highly responsive organic image sensor based on vertically stacked two‐terminal pixels is achieved with pixels of a diode‐type organic photodetector through photomultiplication. With an optimized injection electrode and additionally stacked rectifying layers, the organic image sensor with an extremely simple architecture exhibits a high pixel photoresponse and demonstrates a weak‐light imaging capability at 1 µW cm−2.
A series of piperidine‐naphthalene monoimide, donor−acceptor (D−A) chromophores and their thionated derivatives were prepared. The physical properties of the chromophores were studied by ...spectroscopic and electrochemical measurements and DFT calculations. Relative to their non‐thionated counterparts, the thionated D−A chromophores display enhanced visible‐light absorption and 1O2‐sensitization quantum yields and negligible fluorescence, suggesting facile triplet formation of this class of molecules. This behavior originates from the significant n‐π* character in the singlet excited state, resulting in large spin‐orbit coupling between the singlet/triplet manifolds regardless of the degree of D/A interactions. With the electrochemically active D/A moieties and high triplet energy, the thionated chromophores can be used as amphoteric photosensitizers to catalyze reductive and oxidative photoreactions with efficiency comparable to Ru(bpy)32+ as the sensitizer. Our results demonstrate that thiocarbonylation can be utilized in amide/imide‐containing D−A chromophores to provide a wide range of heavy‐atom‐free redox‐active photosensitizers.
Thiocarbonylation has been shown to be a promising tool for developing heavy‐atom‐free triplet photosensitizers from donor−acceptor chromophores. It was demonstrated that triplet‐state formation from the thiocarbonyls is independent of the donor−acceptor interactions and that the thionated chromophores can be utilized as amphoteric photoredox catalysts that have comparable catalytic activities to common inorganic photosensitizers.
Free base, zinc and palladium π‐extended porphyrins containing fused naphthalenediamide units were employed as photosensitizers in antimicrobial photodynamic therapy (aPDT). Their efficacy, assessed ...by photophysical and in vitro photobiological studies on Gram‐positive bacteria, was found to depend on metal coordination, showing a dramatic enhancement of photosensitizing activity for the palladium complex.
Photo finish it: Antimicrobial photodynamic therapy (aPDT) has been proposed as an alternative approach for the treatment of bacterial infections. Here, free base, zinc and palladium π‐extended porphyrins containing fused naphthalenediamide units were employed as photosensitizers in aPDT, assessed by photophysical and in vitro photobiological studies.
Singlet exciton fission (SF) is a promising strategy for increasing photovoltaic efficiency, but in order for SF to be useful in solar cells, it should take place in a chromophore that is air-stable, ...highly absorptive, solution processable, and inexpensive. Unlike many SF chromophores, diketopyrrolopyrrole (DPP) conforms to these criteria, and here we investigate SF in DPP for the first time. SF yields in thin films of DPP derivatives, which are widely used in organic electronics and photovoltaics, are shown to depend critically on crystal morphology. Time-resolved spectroscopy of three DPP derivatives with phenyl (3,6-diphenylpyrrolo3,4-cpyrrole-1,4(2H,5H)-dione, PhDPP), thienyl (3,6-di(thiophen-2-yl)pyrrolo3,4-cpyrrole-1,4(2H,5H)-dione, TDPP), and phenylthienyl (3,6-di(5-phenylthiophen-2-yl)pyrrolo3,4-cpyrrole-1,4(2H,5H)-dione, PhTDPP) aromatic substituents in 100–200 nm thin films reveals that efficient SF occurs only in TDPP and PhTDPP (τSF = 220 ± 20 ps), despite the fact that SF is most exoergic in PhDPP. This result correlates well with the greater degree of π-overlap and closer π-stacking in TDPP (3.50 Å) and PhTDPP (3.59 Å) relative to PhDPP (3.90 Å) and demonstrates that SF in DPP is highly sensitive to the electronic coupling between adjacent chromophores. The triplet yield in PhTDPP films is determined to be 210 ± 35% by the singlet depletion method and 165 ± 30% by the energy transfer method, showing that SF is nearly quantitative in these films and that DPP derivatives are a promising class of SF chromophores for enhancing photovoltaic performance.
Secondary amines, due to their reactivity, can transform protein templates into catalytically active entities, accelerating the development of artificial enzymes. However, existing methods, ...predominantly reliant on modified ligands or N‐terminal prolines, impose significant limitations on template selection. In this study, genetic code expansion was used to break this boundary, enabling secondary amines to be incorporated into alternative proteins and positions of choice. Pyrrolysine analogues carrying different secondary amines could be incorporated into superfolder green fluorescent protein (sfGFP), multidrug‐binding LmrR and nucleotide‐binding dihydrofolate reductase (DHFR). Notably, the analogue containing a D‐proline moiety demonstrated both proteolytic stability and catalytic activity, conferring LmrR and DHFR with the desired transfer hydrogenation activity. While the LmrR variants were confined to the biomimetic 1‐benzyl‐1,4‐dihydronicotinamide (BNAH) as the hydride source, the optimal DHFR variant favorably used the pro‐R hydride from NADPH for stereoselective reactions (e.r. up to 92 : 8), highlighting that a switch of protein template could broaden the nucleophile option for catalysis. Owing to the cofactor compatibility, the DHFR‐based secondary amine catalysis could be integrated into an enzymatic recycling scheme. This established method shows substantial potential in enzyme design, applicable from studies on enzyme evolution to the development of new biocatalysts.
The importance of protein templates in artificial enzyme design is illustrated through genetic code expansion. Incorporation of a secondary amine into the nucleotide‐binding DHFR and multidrug‐binding LmrR resulted in catalytic entities, with the former favoring the use of NADPH as the hydride source for reactions, whereas the latter required biomimetic 1‐benzyl‐1,4‐dihydronicotinamide (BNAH).
Singlet fission (SF) in two or more electronically coupled organic chromophores converts a high-energy singlet exciton into two low-energy triplet excitons, which can be used to increase solar cell ...efficiency. Many known SF chromophores are unsuitable for device applications due to chemical instability and low triplet state energies. The results described here show that efficient SF occurs in polycrystalline thin films of 9,10-bis(phenylethynyl)anthracene (BPEA), a commercial dye that has singlet and triplet energies of 2.40 and 1.11 eV, respectively, in the solid state. BPEA crystallizes into two polymorphs with space groups C2/c and Pbcn, which undergo SF with k SFA = (109 ± 4 ps)−1 and k SFB = (490 ± 10 ps)−1, respectively. The high triplet energy and efficient SF evidenced from the 180 ± 20% triplet yield make BPEA a promising candidate for enhancing solar cell performance.
Thin films of 5,11‐dicyano‐6,12‐diphenyltetracene (TcCN) have been studied for their ability to undergo singlet exciton fission (SF). Functionalization of tetracene with cyano substituents yields a ...more stable chromophore with favorable energetics for exoergic SF (2E(T1)−E(S1)=−0.17 eV), where S1 and T1 are singlet and triplet excitons, respectively. As a result of tuning the triplet‐state energy, SF is faster in TcCN relative to the corresponding endoergic process in tetracene. SF proceeds with two time constants in the film samples (τ=0.8±0.2 ps and τ=23±3 ps), which is attributed to structural disorder within the film giving rise to one population with a favorable interchromophore geometry, which undergoes rapid SF, and a second population in which the initially formed singlet exciton must diffuse to a site at which this favorable geometry exists. A triplet yield analysis using transient absorption spectra indicates the formation of 1.6±0.3 triplets per initial excited state.
Divide and conquer: Transient absorption measurements reveal sub‐picosecond singlet exciton fission in thin films of a cyano‐substituted diaryltetracene. A triplet yield analysis of the transient absorption data set indicates the formation of 1.6±0.3 triplet excitons per singlet exciton, as a result of rapid and efficient singlet fission.
Dynamic and reversible non‐covalent interactions endow synthetic systems and materials with smart adaptive functions that allow them to response to diverse stimuli, interact with external agents, or ...repair structural defects. Inspired by the outstanding performance and selectivity of DNA in living systems, scientists are increasingly employing Watson−Crick nucleobase pairing to control the structure and properties of self‐assembled materials. Two sets of complementary purine‐pyrimidine pairs (guanine:cytosine and adenine:thymine(uracil)) are available that provide selective and directional H‐bonding interactions, present multiple metal‐coordination sites, and exhibit rich redox chemistry. In this review, we highlight several recent examples that profit from these features and employ nucleobase interactions in functional systems and materials, covering the fields of energy/electron transfer, charge transport, adaptive nanoparticles, porous materials, macromolecule self‐assembly, or polymeric materials with adhesive or self‐healing ability.
Inspired by DNA: H‐bonding interactions between complementary nucleobases, namely G : C and A : T(U), as well as their coordination to metals can be employed for the generation of functional systems and materials with potential applications in diverse fields, including photosynthetic models, porous materials, chemical sensing, drug delivery, or self‐healable polymer networks.
Neoadjuvant immunotherapy and chemotherapy have improved the major pathological response (MPR) in patients with early-stage operable non-small cell lung cancer (NSCLC). This study aimed to assess ...whether the presence of targetable driver mutations affects the efficacy of the combination of immunotherapy and chemotherapy. We enrolled patients with early-stage operable NSCLC who received preoperative neoadjuvant therapy between January 1, 2017, and December 30, 2020. Neoadjuvant therapy was delivered with platinum-doublet chemotherapy; moreover, pembrolizumab was added at the attending physician's discretion based on patient's request. Pathological responses were assessed; moreover, disease-free survival was estimated. Next-generation sequencing was performed in case sufficient preoperative biopsy specimens were obtained. We included 23 patients; among them, 11 received a combination of neoadjuvant immunotherapy and chemotherapy while 12 received neoadjuvant chemotherapy alone. The MPR and pathological complete response rates were 54.5% and 27.3%, respectively, in patients who received a combination of neoadjuvant immunotherapy and chemotherapy. These rates were significantly higher than those in patients who only received neoadjuvant chemotherapy. Three patients in the combination group experienced disease recurrence during the follow-up period even though two of them showed an MPR. These three patients had targetable driver mutations, including an EGFR exon 20 insertion, EGFR exon 21 L858R substitution, and MET exon 14 skipping. Only one patient who remained disease-free had a targetable driver mutation. Among patients with early-stage operable NSCLC requiring neoadjuvant therapy, comprehensive genomic profiling is crucial before the administration of the combination of neoadjuvant immunotherapy and chemotherapy.
Photodriven electron transfer from a donor excited state to an assembly of electronically coupled acceptors has been proposed to enhance charge transfer efficiency in functional organic electronic ...materials. However, the circumstances under which this may occur are difficult to investigate in a controlled manner in disordered donor–acceptor materials. Here we investigate the effects of anion delocalization on electron transfer using zinc meso-tetraphenylporphyrin (ZnTPP) as a donor and a perylene-3,4:9,10-bis(dicarboximide) dimer as the acceptor (PDI2). The PDI units of the dimer are positioned in a cofacial orientation relative to one another by attachment of the imide group of each PDI to the 4- and 5-positions of a xanthene spacer. Furthermore, the distal imide group of one PDI is linked to the para-position of one ZnTPP phenyl group to yield ZnTPP-PDI2. The data for the dimer are compared to two different ZnTPP-PDI monomer reference systems designed to probe electron transfer to each of the individual PDI molecules comprising PDI2. The electron transfer rate from the ZnTPP lowest excited singlet state to PDI2 is increased by 50% relative to that in ZnTPP-PDI, when the data are corrected for the statistics of having two electron acceptors. Femtosecond transient IR absorption spectroscopy provides evidence that the observed enhancement in charge separation results from electron transfer producing a delocalized PDI2 anion.
PDF
