Neuromorphic computing has been extensively studied to mimic the brain functions of perception, learning, and memory because it may overcome the von Neumann bottleneck. Here, with the light‐induced bidirectional photoresponse of the proposed Bi2O2Se/graphene hybrid structure, its potential use in next‐generation neuromorphic hardware is examined with three distinct optoelectronic applications. First, a photodetector based on a Bi2O2Se/graphene hybrid structure presents positive and negative photoresponsibility of 88 and −110 A W−1 achieved by the excitation of visible wavelength and ultraviolet wavelength light at intensities of 1.2 and 0.3 mW cm−2, respectively. Second, this unique photoresponse contributes to the realization of all optically stimulated long‐term potentiation or long‐term depression to mimic synaptic short‐term plasticity and long‐term plasticity, which are attributed to the combined effect of photoconductivity, bolometric, and photoinduced desorption. Third, the devices are applied to perform digital logic functions, such as “AND” and “OR,” using full light modulation. The proposed Bi2O2Se/graphene‐based optoelectronic device represents an innovative and efficient building block for the development of future multifunctional artificial neuromorphic systems.

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ABSTRACT. The Prdm (PRDI-BF1-RIZ1 homologous) family is involved in cell differentiation, and several Prdms have been reported to methylate histone H3 by intrinsic or extrinsic pathways. Here, we report that Prdm12 recruits G9a to methylate histone H3 on lysine 9 through its zinc finger domains. Because of the expression of Prdm12 in the developmental nervous system, we investigated the role of Prdm12 on P19 embryonic carcinoma cells as a model system for neurogenesis. In P19 cells, Prdm12 is induced by Retinoic acid (RA). Overproduction of Prdm12 in P19 cells impairs cell proliferation and increases the G1 population accompanied by the upregulation of p27. In contrast, the knockdown of Prdm12 increases the number of cells in a suspension culture of RA-induced neural differentiation. Both the PR domain and zinc finger domains are required for the anti-proliferative activity of Prdm12. While the data in this study is based on in vitro models, the results suggest that Prdm12 is induced by the RA signaling in vivo, and may regulate neural differentiation during animal development.

We perform comprehensive long-time monitoring of the p-doping and de-doping of poly͑3-hexyl thiophene͒ under changing external conditions of oxygen, light, and temperature. They are shown to be controlled by the complex adsorption and desorption process with time scales ranging from seconds to weeks. The oxygen doping at atmospheric pressure takes several hours in the dark. The doping is dramatically accelerated to be within seconds with light of wavelength of 500-700 nm. Even at low oxygen pressure of 10 −4 torr doping occurs within minutes with light. The de-doping by oxygen desorption takes as long as weeks at room temperature and vacuum of 10 −4 torr, but when the temperature is raised to near the polymer glass temperature of 370 K, the de-doping is accelerated to minutes as the enhanced chain motion releases the trapped oxygen. Even though visible and near infrared light causes very efficient doping within seconds or minutes depending on vacuum level, such light-induced doping is not a chemical reaction and is fully reversible by thermal annealing at the end without sacrificing the mobility. For the polymer field-effect transistors, only the carrier density is changed while the mobility remains roughly a constant for all the conditions.

Ir complex was doped to conjugated polymers, and the photoinduced absorption of triplet excitons in host materials was examined. A greatly enhanced intersystem crossing rate was observed, despite the decrease in triplet exciton lifetime. The authors find that the steady-state triplet exciton population in host polymer would increase by an order of magnitude. Conjugated polymer/colloidal CdSe nanocrystal hybrid solar cells were fabricated and the effect of Ir-complex doping on photovoltaic response was studied. It was found that due to the enhanced singlet-to-triplet conversion, greatly enhanced photovoltaic response of these hybrid organic solar cells was observed. The results suggest that triplet solar cells may be achieved by doping conventional photovoltaic materials with transition-metal complexes.