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Metal halide perovskites are promising candidates for γ-ray spectrum detectors. However, achieving high-resolution energy spectra in single-photon pulse-height analysis mode remains challenging, due to the inevitable leakage currents degrade the recognizable fingerprint energies which is critical for resolving γ-ray spectroscopy. We demonstrate under high bias voltage, a deficient contact barrier can lead to excessive surface charge injection, thereby increasing leakage current from electrodes to perovskites. Hence, we conceive to employ surface ligand engineering on perovskite single crystals to manipulate energy levels to suppress leakage current. In particular, anchoring a strong dipole ligand onto the perovskite induced surface charge-density displacement, leading to a downward band bending and heightened the corresponding contact barrier. Consequently, the strategy minimized the detectors'leakage current by an order of magnitude, to as low as 44 nA cm-2. The resulting detectors show a significant improvement in energy resolution, 3.9% for 22Na 511 keV γ-rays has been achieved at room temperature. The resulting detector further resolves each fingerprint energy for 152Eu γ-spectrum, representing one of the best γ-rays perovskite detectors reported to date. Moreover, the detectors exhibited stabilized energy resolution without any degradation under a continuous electric field for over 300 minutes, representing the longest longevity reported to date.

RESUMEN

Bion's notion of the contact-barrier formulates a semipermeable membrane responsible for preserving the distinction between the conscious and the unconscious. However, the question of how a newly established contact-barrier manifests itself in dreams remains unanswered. The author proposes that one such manifestation occurs when a patient sees themself asleep in a dream. A case of a severely traumatized woman who had difficulty thinking and being close to others is used to explore these clinical ideas. The author, in response to his reveries in a session, introduced a playful dream-like dialogue between a playwright and his reader. The nature of the communication, in functioning as a barrier, served to protect the patient from a tyrannizing reality: the therapist's sexuality. This intersubjective barrier helped the patient to contact dissociated and damaged parts of herself, and it also facilitated her ability to dream a sense of her own boundaries, femininity, and sexuality.

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Organic field-effect transistors (OFETs) have the advantages of low-cost, large-area processing and could be utilized in a variety of emerging applications. However, the generally large contact resistance (Rc) limits the integration and miniaturization of OFETs. The Rc is difficult to reduce due to an incompatibility between obtaining strong orbit coupling and the barrier height reduction. In this study, we developed an oxygen-induced barrier lowering strategy by introducing oxygen (O2) into the nanointerface between the electrodes and organic semiconductors layer and achieved an ultralow channel width-normalized Rc (Rc·W) of 89.8 Ω·cm and a high mobility of 11.32 cm2 V-1 s-1. This work demonstrates that O2 adsorbed at the nanointerface of metal-semiconductor contact can significantly reduce the Rc from both experiments and theoretical simulations and provides guidance for the construction of high-performance OFETs, which is conducive to the integration and miniaturization of OFETs.

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2D semiconductors, such as MoS2 have emerged as promising ultrathin channel materials for the further scaling of field-effect transistors (FETs). However, the contact barrier at the metal-2D semiconductor junctions still significantly limits the device's performance. By extending the application of electrochemical deposition in 2D electronics, a distinct approach is developed for constructing metal-2D semiconductor junctions in an edge-contacted configuration through the edge-guided electrodeposition of varied metals. Both high-resolution microscopic imaging and electrical transport measurements confirm the successful creation of high-quality Pd-2D MoS2 junctions in desired geometry by combining electrodeposition with lithographic patterning. FETs are fabricated on the obtained Pd-2D MoS2 junctions and it is confirmed that these junctions exhibit a reduced contact barrier of ≈20 meV and extremely low contact resistance of 290 Ω µm and thus increase the averaged mobility of MoS2 FETs to ≈108 cm2 V -1 s-1 . This approach paves a new way for the construction of metal-semiconductor junctions and also demonstrates the great potential of the electrochemical deposition technique in 2D electronics.

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Rhenium-based 2D transition metal dichalcogenides such as ReSe2 are suitable candidates as photoactive materials for optoelectronic devices. Here, photodetectors based on mechanically exfoliated ReSe2 crystals were fabricated using chemical vapor deposited (CVD) graphene single-crystal (GSC) as lateral contacts. A "pick & place" method was adopted to transfer the desired crystals to the intended position, easing the device fabrication while reducing potential contaminations. A similar device with Au was fabricated to compare contacts' performance. Lastly, a CVD hexagonal boron nitride (hBN) substrate passivation layer was designed and introduced in the device architecture. Raman spectroscopy was carried out to evaluate the device materials' structural and electronic properties. Kelvin probe force measurements were done to calculate the materials' work function, measuring a minimal Schottky barrier height for the GSC/ReSe2 contact (0.06 eV). Regarding the electrical performance, I-V curves showed sizable currents in the GSC/ReSe2 devices in the dark and under illumination. The devices presented high photocurrent and responsivity, along with an external quantum efficiency greatly exceeding 100%, confirming the non-blocking nature of the GSC contacts at high bias voltage (above 2 V). When introducing the hBN passivation layer, the device under white light reached a photo-to-dark current ratio up to 106.

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The improvement of antimony selenide solar cells by short-term air exposure is explained using complementary cell and material studies. We demonstrate that exposure to air yields a relative efficiency improvement of n-type Sb2Se3 solar cells of ca. 10% by oxidation of the back surface and a reduction in the back contact barrier height (measured by J-V-T) from 320 to 280 meV. X-ray photoelectron spectroscopy (XPS) measurements of the back surface reveal that during 5 days in air, Sb2O3 content at the sample surface increased by 27%, leaving a more Se-rich Sb2Se3 film along with a 4% increase in elemental Se. Conversely, exposure to 5 days of vacuum resulted in a loss of Se from the Sb2Se3 film, which increased the back contact barrier height to 370 meV. Inclusion of a thermally evaporated thin film of Sb2O3 and Se at the back of the Sb2Se3 absorber achieved a peak solar cell efficiency of 5.87%. These results demonstrate the importance of a Se-rich back surface for high-efficiency devices and the positive effects of an ultrathin antimony oxide layer. This study reveals a possible role of back contact etching in exposing a beneficial back surface and provides a route to increasing device efficiency.

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With the publication of Wilfred Bion's text 'Learning from Experience,' psychoanalysis was afforded a new schema for understanding the processes and implications involved in an infant's contact with their caregivers. As a result, our conception of some of the most fundamental phenomena of psychic life was significantly enriched. By proposing his theory of alpha-functioning, Bion mapped out how meaningful connexions to the internal and external worlds become established in the mind. In contrast, and through working clinically with psychotic patients, Bion revealed how these ties can catastrophically come undone. It is with these ideas, as well as their links to a corresponding set of neuroscientific constructs relating to the Markov blanket and principally developed by Karl Friston, that this paper is concerned. Through an investigation of the psychic functioning originally dubbed 'dream-work-alpha,' the paper's first section focuses on how Bion conceived of the creation of a 'contact-barrier' that allows for the differentiation of consciousness from an unconscious mind. Casting the ramifications of this organisation in sharp relief, the psychotic disorganisation of the contact-barrier is then explored. The discussion subsequently broadens to incorporate contemporary theories from free energy neuroscience that bear significant and illuminating relations to the psychoanalytic ideas espoused by Bion over half a century ago. Finally, through posing a series of three questions with accompanying discussions, a superimposition of these theoretical schemas is attempted. These suggestions directly address, (1) whether there is an intimate connexion between the interoceptive contact-barrier and the exteroceptive Markov blanket, (2) whether a disobjectalising of the contact-barrier may be reflected as a tear in the functional fabric of the Markov blanket, and (3) what the clinical implications are of working at the level of the projected surface. Ultimately, the aim of the paper is to expose relevant points of contact within and between the varying conceptual frameworks; frameworks that ultimately derive from disciplines that are both concerned with examining the underlying mechanisms of the mind-brain.

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In this essay the term 'scene' which has been developed in the German psychoanalytic discussion, is confronted with the terms 'total situation' and 'psychoanalytic field', showing common features as well as differences. Thereafter four child observations are presented, through which light is thrown onto the scenic structures which make the foundations of early experience. In the precedence of scenes those structures are omnipresent whereas subjectivity only gradually builds up. It is shown how the development of subjectivity and the differentiation of consciousness and unconscious go along with overcoming the precedence of scenes, by breaking them up and reorganizing them. Thus scenes can become metaphors, which are used for 'translating' experience and for building up the contact barrier.

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RESUMEN

A clinical vignette is used as the starting point for an exploration of Bion's notion of a contact-barrier, which "separates mental phenomena into two groups one of which performs the functions of consciousness and the other the functions of unconsciousness" (Bion, 1962a, p. 22), and its relation to Freud's drive theory. Bion's concept is compared to Freud's (1950[1895]) description of the 'contact-barrier' in the Project for a scientific psychology. Through this comparison, light is shed on various aspects of Bion's metapsychology, especially on the notion of 'beta-elements', described by Bion in quantitative/energetic terms as 'accretions of stimuli'. The processing of beta-elements through the function of the contact-barrier is understood as an elaboration of Freud's notion of the 'binding' of the drives, with the difference that beta-elements encompass 'unprocessed' external stimuli as well as impulses arising from within. The 'beta-element' and the 'drives' are both understood as concepts that delimit what is knowable in the psyche. Further clinical material is presented to illustrate the author's argument that Bion's contact-barrier and related concepts (alpha function, containment) should be understood with reference to the economic/energetic aspect of Freud's metapsychology.

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By electrochemically p-doping pentacene in the vicinity of the source-drain electrodes in organic field effect transistors the injection barrier for holes is decreased. The focus of this work is put on the influence of the p-doping process on the transistor performance. Cyclic voltammetry performed on a pentacene based transistor exhibits a reversible p-doping response. This doped state is evoked at the transistor injection electrodes. An improvement is observed when comparing transistor characteristics before and after the doping process apparent by an improved transistor on-current. This effect is reflected in the analysis of the contact resistances of the devices.