The main focus of this thesis is the characterization of the charge transport in CdZnTe radiation detectors and the study of the effect of the detector illumination on charge transport. The transport properties are evaluated using Laser-induced Transient Current Technique and the Monte Carlo simulation is used for fitting the measured current waveforms. The properties of the detector prepared from semi-insulating CdZnTe single crystal with a platinum Schottky contacts were measured in the dark in the unpolarized and polarized state and under the anode and cathode continuous LED above-bandgap illumination.

The efficiency and mechanism of electron- and energy transfer events occurring in both in natural and synthetic donor-acceptor systems depend on their distance, relative orientation, and the nature of the surrounding media. Fundamental knowledge gained from model studies is key in building efficient energy harvesting and optoelectronic devices. Faster charge separation and slower charge recombination in donor-acceptor systems is often sought out. In our continued effort to build donor-acceptor systems using near-IR sensitizers, in the present study, we report ground and excited state charge transfer in newly synthesized, directly linked, tetrads featuring bisdonor (donor = phenothiazine and ferrocene), BF2-chelated azadipyrromethane (azaBODIPY) and C60 entities. The tetrads synthesized using multi-step synthetic procedure revealed strong charge transfer interactions in the ground state involving the donor and azaBODIPY entities. The near-IR emitting azaBODIPY acted as a photosensitizing electron acceptor along with fullerene while the phenothiazine and ferrocene entities acted as electron donors. The triads (bisdonor-azaBODIPY) and tetrads revealed ultrafast photoinduced charge separation leading to D•+-azaBODIPY•–-C60 and D•+-azaBODIPY-C60•– (D = phenothiazine or ferrocene) charge separated states from the femtosecond transient absorption spectral studies in both polar and nonpolar solvent media. The charge separated states populated the triplet excited state of azaBODIPY prior returning to the ground state.

Abstract: Understanding and controlling the ultrafast charge carrier and exciton dynamics at the interface of semiconductor nanocrystals (NCs) offer an excellent opportunity to improve the charge collection and the overall performance of many optoelectronic and energy-based devices. In this dissertation, we study how interfacial engineering of these materials can have a direct influence on controlling the charge transfer and the nonradiative losses in different donor-acceptor systems. The first introductory chapter provides an overview of all the fundamental photophysical processes controlling the interfacial phenomena. Then, the second chapter highlights all the chemicals and synthesis methods employed during this thesis. The subsequent two chapters discuss the detailed experimental studies and observations related to different materials and interfaces. First, it describes how we can dramatically tune the intersystem crossing (ISC) rate, the triplet state lifetime, turn on/off the electron injection at the CdTe-Prophyrin interface via tuning either the quantum dot size or the porphyrin molecular structure. Also, how the intermolecular distances, electronic coupling, and subsequently, the photoinduced charge transfer can be controlled by the interfacial electrostatic interactions at CdTe-Fullerene interfaces. Second, due to the promise that of perovskite NCs holds for improving many solar cell and optoelectronic applications, chapter 3 highlights the tremendous effect that the shape of perovskite nanocrystals has on the rate and the mechanism of charge transfer at the MAPbBr3- TCNE interface. Besides, it demonstrates how the confinement effect brought by changing the dimensionality influence the charge transfer dynamics at the MAPbBr3-BQ interface. Finally, it explains how the effective passivation of the surface defects and the subsequent suppression of the formation of surface nonradiative recombination centers in CsPbCl3 NCs controls the photoluminescence quantum yield and the photodetector performance.

Artificial photosynthesis is the process, which mimics the natural photosynthesis process in order to convert solar energy to chemical energy. This process can be separated into four parts, which are antenna system, reaction center, water oxidation center, and proton reduction center. If we only focus on the ‘antenna system and reaction center' modules, expanding the absorption band in antenna system and generating long-lived charge separated state in reaction center are two fantastic strategies to design the molecules in order to improve the efficiency of the artificial photosynthesis process. In the first work of this dissertation, mono-18-crown-6 and mono-ammonium binding strategy was used to connect BODIPY- C60 supramolecular based donor–acceptor conjugates. The meso- position of BODIPY was modified by benzo-18-crown-6, and the 3, 5 methyl positions were replaced by two styryl groups, which covered additional donor (triphenylamine or 10-methylphenothiazine). The acceptor is a fulleropyrrolidine derivative, which included an ethyl ammonium cation. The absorbance wavelengths of the donor covered 300-850 nm, which is the visible/near IR region (wide band capturing). The ultrafast charge separation and relatively slow charge recombination was found from femtosecond transient absorption study. Next, a ‘two point' bis-18-crown-6 and bis-ammonium binding strategy was utilized to link BODIPY- C60 supramolecular based donor–acceptor conjugates. In this case, the meso- position of the BODIPY was modified by a secondary donor (triphenylamine, phenothiazine, or ferrocene). And the 3, 5 methyl positions were replaced by two styryl groups, which included benzo-18-crown-6. The acceptor (fulleropyrrolidine) was functionalized by bis-alky ammonium cations. The absorbance/ fluorescence emission titration and computational studies supported that the ‘two-point' strategy has stronger binding than ‘one-point' strategy. The relatively slow charge separation was found in these donor-acceptor conjugates. To extend the second work, a pristine BODIPY was linked to the meso- position of the BODIPY-bis-benzo-18-crown-6. When the acceptor (C60-bis- ammonium) was added to the system, a sequential energy transfer (EnT) followed by electron transfer (ET) process was performed. The energy transfer was found from absorbance/ fluorescence emission studies, and the photoinduced electron transfer was observed from femtosecond and nanosecond transient absorption study. This is a great mode to mimic the ‘antenna-reaction center' events of natural photosynthesis. In the last work of this dissertation, triplet sensitizers (I2BODIPY and I2azaBODIPY) covalently linked with a C60 to form the donor-acceptor system. In this work, triplet charge separated state (long-lived charge separated state) was expected. According to the femtosecond transient absorption studies, we observed the singlet charge separation was faster than the intersystem crossing process, that was the reason that only singlet charge separated state was found for I2BODIPY-C60, and no electron transfer was found for I2 azaBODIPY-C60.

Fabrication of high-performance electronic devices using the novel semiconductors is essential for developing future electronics which can be applicable in large-area, flexible and transparent displays, sensors and solar cells. One of the major bottlenecks in the fabrication of high-performance devices is a large interfacial barrier formation at metal/semiconductor interface originated from Schottky barrier and interfacial dipole barrier which causes inefficient charge injection at the interface. Therefore, having a favorable contact at electrode/semiconductor is highly desirable for high-performance devices fabrication. In this dissertation, the fabrication of nanoelectronic devices and investigation of their transport properties using carbon nanotubes (CNTs) and graphene as electrode materials will be shown. I investigated two types of devices using (i) semiconducting CNTs, and (ii) organic semiconductors (OSC). In the first part of this thesis, I will demonstrate the fabrication of high-performance solution-processed highly enriched (99%) semiconducting CNT thin film transistors (s-CNT TFTs) using densely aligned arrays of metallic CNTs (m-CNTs) for source/drain electrodes. From the electronic transport measurements at room temperature, significant improvements of field-effect mobility, on-conductance, transconductance and current on/off ratio for m-CNT/s-CNT devices were found compared to control palladium (Pd contacted s-CNT devices. From the temperature dependent transport investigation, a lower Schottky barrier height for the m-CNT/s-CNT devices was found compared to the devices with control metal electrodes. The enhanced device performance can be attributed to the unique device geometry as well as strong ?- ? interaction at m-CNT/s-CNT interfaces. In addition, I also investigated s-CNT TFTs using reduced graphene oxide (RGO) electrodes. In the second part of my thesis, I will demonstrate high-performance organic field-effect transistors (OFETs) using different types of graphene electrodes. I show that the performance of OFETs with pentacene as OSC and RGO as electrode can be continuously improved by increasing the carbon sp2 fraction of RGO. The carbon sp2 fractions of RGO were varied by controlling the reduction time. When compared to control Pd electrodes, the mobility of the OFETs shows an improvement of ?200% for 61% sp2 fraction RGO, which further improves to ?500% for 80% RGO electrode. Similarly, I show that when the chemical vapor deposition (CVD) graphene film is used as electrodes in fabricating OFET, the better performance is observed in comparison to RGO electrodes. Our study suggests that, in addition to ?-? interaction at graphene/pentacene interface, the tunable electronic properties of graphene as electrode have a significant role in OFETs performance. For a fundamental understanding of the interface, we fabricated short-channel OFETs with sub-100nm channel length using graphene electrode. From the low temperature electronic transport measurements, a lower charge injection barrier was found compared to control metal electrode. The detailed investigations reported in this thesis clearly indicated that the use of CNT and graphene as electrodes can improve the performance of future nanoelectronic devices.

Organic field effect transistors (OFETs) are of significant research interest due to their promising applications in large area, low-cost electronic devices such as flexible displays, sensor arrays, and radio-frequency identification tags. A major bottleneck in fabricating highperformance OFET is the large interfacial barrier between the metal electrodes and organic semiconductors (OSC) which results in an inefficient charge injection. Carbon nanotubes (CNTs) are considered to be a promising electrode material which can address this challenge. In this dissertation, we demonstrate fabrication of high-performance OFETs using aligned array CNT electrodes and investigate the detailed electronic transport properties of the fabricated devices. The OFETs with CNT electrodes show a remarkable enhancement in the device performance such as high mobility, high current on-off ratio, higher cutoff frequency, absence of short channel effect and better charge carrier injection than those OFETs with metal electrodes. From the low temperature transport measurements, we show that the charge injection barrier at CNT/OSC interface is smaller than that of the metal/OSC interface. A transition from direct tunneling to Fowler-Nordheim tunneling observed in CNT/OSC system shows further evidence of low injection barrier. A lower activation energy measured for the OFETs with CNT electrodes gives evidence of lower interfacial trap states. Finally, OFETs are demonstrated by directly growing crystalline organic nanowires on aligned array CNT electrodes. In addition to investigating the interfacial barrier at CNT/OSC interface, we also studied photoconduction mechanism of the CNT and CNT/OSC nanocomposite thin film devices. We found that the photoconduction is due to the exciton dissociations and charge carrier separation caused by a Schottky barrier at the metallic electrode/CNT interface and diffusion of the charge iv carrier through percolating CNT networks. In addition, it is found that photoresponse of the CNT/organic semiconductor can be tuned by changing the weight percentage of CNT into the organic semiconductors.

Charge detection mass spectrometry (CDMS) is a single particle technique capable of simultaneously measuring charge and mass-to-charge ratios for individual ions or particles. The linear array CDMS design theoretically has no upper mass limit and is therefore a choice method for the analysis of high mass and heterogeneous samples, such as dust microparticles in the Martian atmosphere. This dissertation describes the development of a novel charge detection mass spectrometer made of printed circuit boards (PCB) for the analysis of dust microparticles in the Martian atmosphere. Development of this device has required investigations in analysis methods and the engineering design of both the PCB device and the vacuum chamber system used in laboratory experiments. Accurate velocity analysis is crucial in determining correct particle mass in linear array CDMS. By combining the Shockley-Ramo theorem–which allows for the calculation of instantaneous image current for a system of electrodes when a point charge passes them–and SIMION ion optics simulations effective electrode length can be determined for any given charge detector geometry and aid in charge detector engineering and design process. Applying these simulation results to experimental data yields velocity agreement for a PCB charge detector within 0.44% RSD. The novel PCB CDMS device was demonstrated for the analysis of multiple types of microparticles of varying size and charge similar to that expected of atmospheric Mars dust. This device is able to measure particle charge above 1,500 elementary charges of either polarity. Simulations show that for microparticles having a size and density close to that which is expected for Mars dust, the device is able to ideally measure the mass of particles ranging from 0.2–2.5 μm in diameter, providing broad coverage of particles too small to be observed by optical scattering and other techniques that have been previously used on Mars.

Los dispositivos CCDs (por las siglas en inglés de Charge Coupled Devices) son aún hoy en día la tecnología líder para la toma de imágenes de baja distorsión y son ampliamente utilizados en aplicaciones de astronomía en el rango de la luz visible y en el infrarrojo cercano. En esta tesis se estudia y desarrolla su utilización para la detección de otras partículas diferentes a los fotones de luz, en particular para partículas con muy poca probabilidad de detección y muy poca deposición de energía logrando que esta nueva tecnología presente una ventaja respecto a detectores disponibles hoy en día. Los resultados de esta tesis son la base del desarrollo de una aplicación de un sistema de CCDs para la detección de neutrinos provenientes de un reactor nuclear. Se estudian las características principales de los CCDs que los hacen aptos para esta novedosa aplicación, y se encuentra que la mayor limitante de su rendimiento es el ruido de lectura agregado por su etapa de salida. Se desarrolla una técnica para reducir su incidencia, y mejorar así la capacidad de detección. A partir de estas características se analiza la capacidad de los CCD para detectar neutrinos provenientes de un reactor nuclear por medio de la interacción coherente entre el neutrino y los núcleos de los átomos de silicio. Para optimizar la detección de eventos de este tipo en las imágenes de salida, se deriva un modelo matemático que estudia el mecanismo de generación de carga en el CCD y se desarrolla una técnica de calibración que permite obtener información de la profundidad a la que se produce la ionización Estos resultados se plasmaron en el desarrollo de un prototipo instalado en la Central Nuclear Almirante Álvaro Alberto, en Angra dos Reis, Brasil. Se muestran algunos resultados preliminares obtenidos con este prototipo, y se comentan las mejoras que se realizarán próximamente en este sistema. / Charge Coupled Devices are still nowadays the best available technology for low distortion digital imaging applications and are extensively used for ground and spacebased astronomy for visible light and near infrared. In this thesis, studies to extent its use to applications for the detection of particles different to light photons are presented, in particular for those particles having low probability of interaction and small deposition of energy for which this technology presents advantages over available detectors. These studies are the base for the development of a CCD system aiming the detection of low energy neutrinos coming out from a nuclear reactor. The most important aspects of scientific CCDs for particle detection are revisited, and its main detection limitation produced by the readout noise added by the output amplifier of the device is explained. A technique to reduce the effect of this noise and to improve the detection performance is developed. The main features of CCDs are then used to analyze the feasibility of detecting low energy neutrinos through their coherent scattering with nuclei. A mathematical model of the expected signal in the output images is obtained and a new technique for the calibration of the CCDs to obtained the depth of the interaction in the silicon is developed. This result is used to improve the detection performance of the system The first CCD system prototype for this application is presented together with some details of its installation at Central Nuclear Almirante Alvaro Alberto in Angra dos Reis, Brazil, and some preliminary results are discuSSED.

Titre de l'écran-titre (visionné le 24 juillet 2023) / L'opérateur en surveillance urbaine est appelé à observer et analyser plusieurs sources vidéo en simultané afin de détecter les comportements potentiellement à risque pour la sécurité de la population. L'efficacité à détecter des incidents repose sur la capacité à comprendre les différents aspects d'une situation parfois complexe et son l'évolution afin de pouvoir projeter son état dans le temps et en déterminer le potentiel critique (Stainer et coll., 2013). L'opérateur sollicite ainsi plusieurs ressources cognitives importantes qui peuvent devenir lourdes à gérer lors d'une tâche de recherche visuelle au sein d'un environnement visuel saturé ou lors de l'évaluation du potentiel critique d'une situation (Hodgetts et coll., 2017). Paradoxalement, les environnements de surveillance traditionnels ont tendance encore aujourd'hui à présenter une grande quantité d'information à la fois, suggérant une meilleure efficacité de détection quand l'opérateur peut accéder à toutes les sources disponibles simultanément (Smallman et John, 2005). Pourtant, bien qu'intuitive, cette approche tend au contraire à générer un impact négatif sur la performance (Stainer et coll., 2021) puisque l'outil multiplex est inadapté à la réalité cognitive des utilisateurs (Stainer et coll., 2013; Tickner et Poulton, 1973) qui s'avère opérer un traitement sériel de l'information pour certains aspects clés d'une tâche de détection (Zelinsky et Loschky, 2005). Le présent projet vise par une approche de recherche holistique (Lafond et coll., 2010) et systémique (Sevaldson, 2013) et par une méthodologie à l'intersection des sciences et du design à supporter l'utilisateur dans sa tâche afin d'harmoniser l'outil de visualisation avec sa réalité cognitive lors d'une tâche de surveillance. Cette stratégie permet d'associer différents phénomènes d'un point de vue global, mais également en termes d'influence mutuelle des dimensions cognitives concomitantes afin d'assurer le confort interactionnel et cognitif de l'utilisateur. Un environnement sériel monoplex est comparé à une interface traditionnelle multiplex afin de comprendre l'effet du mode de visualisation sur la performance de surveillance. Dans son état actuel, l'interface monoplex harmonisée avec les processus sériels de l'attention ne s'avère pas améliorer la performance de détection, mais augmente cependant la conscience de la situation sans générer de coût au niveau de la charge mentale, ce qui souligne le potentiel de la sériation en recherche visuelle. L'analyse des phénomènes cognitifs semble démontrer que la sérialité seule n'est pas suffisante pour améliorer la performance, mais qu'elle gagnerait à être mise en relation avec d'autres facteurs d'influence pour avoir un impact significatif sur la performance en surveillance. Les résultats démontrent que la valeur attribuée aux incidents à détecter s'avère être le facteur prédominant de la détection selon le modèle NSEEV de l'attention (Steelman et coll., 2011), et gagnerait à être considéré dans l'intégration de la sérialité en surveillance, notamment lorsqu'on considère l'approche monoplex comme étant plus cohérente avec les tâches de nature descendantes (Treisman et Gelade, 1980) vu la plus grande facilité à s'y concentrer sur un élément spécifique à la fois (Stainer et coll., 2013). À la lumière des résultats, un concept hybride modulaire est exploré pour supporter une approche par scène ou par regroupement de proximité sémantique (Tatler, 2021) qui s'aligne davantage avec les différents types de traitement cognitif sollicités en recherche visuelle.

In view of the importance of charge storage in polymer electrets for electromechanical transducer applications, the aim of this work is to contribute to the understanding of the charge-retention mechanisms. Furthermore, we will try to explain how the long-term storage of charge carriers in polymeric electrets works and to identify the probable trap sites. Charge trapping and de-trapping processes were investigated in order to obtain evidence of the trap sites in polymeric electrets. The charge de-trapping behavior of two particular polymer electrets was studied by means of thermal and optical techniques. In order to obtain evidence of trapping or de-trapping, charge and dipole profiles in the thickness direction were also monitored. <br><br> In this work, the study was performed on polyethylene terephthalate (PETP) and on cyclic-olefin copolymers (COCs). PETP is a photo-electret and contains a net dipole moment that is located in the carbonyl group (C = O). The electret behavior of PETP arises from both the dipole orientation and the charge storage. In contrast to PETP, COCs are not photo-electrets and do not exhibit a net dipole moment. The electret behavior of COCs arises from the storage of charges only. <br><br> COC samples were doped with dyes in order to probe their internal electric field. COCs show shallow charge traps at 0.6 and 0.11 eV, characteristic for thermally activated processes. In addition, deep charge traps are present at 4 eV, characteristic for optically stimulated processes. <br><br> PETP films exhibit a photo-current transient with a maximum that depends on the temperature with an activation energy of 0.106 eV. The pair thermalization length (rc) calculated from this activation energy for the photo-carrier generation in PETP was estimated to be approx. 4.5 nm. The generated photo-charge carriers can recombine, interact with the trapped charge, escape through the electrodes or occupy an empty trap. <br><br> PETP possesses a small quasi-static pyroelectric coefficient (QPC): ~0.6 nC/(m²K) for unpoled samples, ~60 nC/(m²K) for poled samples and ~60 nC/(m²K) for unpoled samples under an electric bias (E ~10 V/µm). When stored charges generate an internal electric field of approx. 10 V/µm, they are able to induce a QPC comparable to that of the oriented dipoles. Moreover, we observe charge-dipole interaction. Since the raw data of the QPC-experiments on PETP samples is noisy, a numerical Fourier-filtering procedure was applied. Simulations show that the data analysis is reliable when the noise level is up to 3 times larger than the calculated pyroelectric current for the QPC. <br><br> PETP films revealed shallow traps at approx. 0.36 eV during thermally-stimulated current measurements. These energy traps are associated with molecular dipole relaxations (C = O). On the other hand, photo-activated measurements yield deep charge traps at 4.1 and 5.2 eV. The observed wavelengths belong to the transitions in PETP that are analogous to the π - π* benzene transitions. The observed charge de-trapping selectivity in the photocharge decay indicates that the charge detrapping is from a direct photon-charge interaction. Additionally, the charge de-trapping can be facilitated by photo-exciton generation and the interaction of the photo-excitons with trapped charge carriers. These results indicate that the benzene rings (C6H4) and the dipolar groups (C = O) can stabilize and share an extra charge carrier in a chemical resonance. In this way, this charge could be de-trapped in connection with the photo-transitions of the benzene ring and with the dipole relaxations. <br><br> The thermally-activated charge release shows a difference in the trap depth to its optical counterpart. This difference indicates that the trap levels depend on the de-trapping process and on the chemical nature of the trap site. That is, the processes of charge detrapping from shallow traps are related to secondary forces. The processes of charge de-trapping from deep traps are related to primary forces. Furthermore, the presence of deep trap levels causes the stability of the charge for long periods of time. / Angesichts der Bedeutung der Ladungsspeicherung in Polymerelektreten für viele Anwendungen, wie z.B. in elektromechanischen Wandler, ist es das Ziel dieser Arbeit, zum Verständnis der zugrundeliegenden Mechanismen der kurz- und langfristigen Ladungsstabilisierung beizutragen sowie mögliche Haftstellen zu identifizieren. Ladungs- und Entladungsprozesse in Elektreten geben Hinweise auf Ladungshaftstellen. Diese Prozesse wurden mit thermischen und optischen Methoden bei gleichzeitiger Messung von Ladungs- und Polarisationprofilen untersucht. Die experimentellen Untersuchungen der vorliegenden Arbeit wurden an Polyethylenterephthalat (PETP) und an Cyclischen-Olefin Copolymeren (COC) durchgeführt. <br><br> PETP ist ein Photoelektret und weist in der Carbonylgruppe (C = O) ein Dipolmoment auf. Die Elektreteigenschaften ergeben sich sowohl aus der Orientierungspolarisation als auch aus der Ladungsspeicherung. Im Gegensatz zu PETP ist COC kein Photoelektret und zeigt auch keine Orientierungspolarisation. Deshalb folgen die Elektreteigenschaften des COC ausschließlich aus der Ladungsspeicherung. Die COC-Proben wurden mit Farbstoffen dotiert, um das innere elektrische Feld zu untersuchen. Diese Systeme zeigen flache Ladungshaftstellen bei 0,6 und 0,11 eV, die durch thermisch stimulierte Prozesse entladen werden sowie tiefe Haftstellen bei 4 eV, die optisch stimuliert werden können. <br><br> PETP-Filme zeigen einen transienten Photostrom mit einem Maximalwert ( jp), der von der Temperatur mit einer Aktivierungsenergie von 0,106 eV abhängt. Der thermische Paarabstand (rc) kann für die Photoladungsgeneration in PETP auf ca. 4,5 nm abgeschätzt werden. Die Photoladungsträger können rekombinieren, mit den gespeicherten Ladungen interagieren, über die Elektroden entkommen oder eine leere Haftstelle einnehmen. <br><br> PETP zeigt einen kleinen quasi-statischen pyroelektrischen Koeffizienten (QPC) von ca. 0,6 nC/(m²K) für nicht polarisierte Proben, ca. 60 nC/(m²K) für polarisierte Proben und ca. 60 nC/(m²K) für nicht polarisierte Proben mit Vorspannung (E ~10 V/µm). Wenn die gespeicherten Ladungen ein internes elektrisches Feld von ca. 10 V/µm generieren können, sind sie in der Lage, einen QPC herbeizuführen, der vergleichbar mit dem von orientierten Dipolen ist. Es ist außerdem möglich, eine Ladungs-Dipol-Wechselwirkung zu beobachten. Da die QPM-Daten von PETP auf Grund des geringen Signals verrauscht sind, wurde ein numerisches Fourier-Filterverfahren angewandt. Simulationen zeigen, dass eine zuverlässige Datenanalyse noch bei einem Signal möglich ist, dessen Rauschen bis zu 3-mal größer ist als der berechnete pyroelektrische Strom. <br><br> Messungen der thermisch stimulierten Entladung von PETP-Filmen ergaben flache Haftstellen bei ca. 0,36 eV, welche mit der Dipolrelaxation der Carbonylgruppe (C = O) assoziiert sind. Messungen der photostimulierten Entladung ergaben tiefe Haftstellen bei 4,1 und 5,2 eV. Die beobachteten Wellenlängen entsprechen Übergängen in PETP analog den π - π* Übergängen in Benzol. Die beobachtete Selektivität bei der photostimulierten Entladung lässt auf eine direkte Wechselwirkung von Photonen und Ladungen schließen. Einen zusätzlichen Einfluß auf die Entladung hat die Erzeugung von Photo-Exzitonen und deren Wechselwirkung mit den gespeicherten Ladungsträgern. Diese Ergebnisse deuten darauf hin, dass die Phenylringe (C6H4) und die Dipolgruppen (C = O) eine zusätzliche Ladung in einer chemischen Resonanz stabilisieren und miteinander teilen können. Daher kann die gebundene Ladung auch durch einen Photoübergang im Benzolring oder durch eine Dipolrelaxation freigesetzt werden. <br><br> Die mittels thermisch stimulierter Entladung bestimmte Tiefe der Haftstellen unterscheidet sich deutlich von den mittels photostimulierter Entladung gemessenen Werten. Flachere Haftstellen werden bei der thermisch stimulierten Entladung gefunden und können sekundären Kräften zugeordnet werden. Die tieferen Haftstellen sind chemischer Natur und können primären Kräften zugeordnet werden. Letztere sind für die Langzeitstabilität der Ladung in Polymerelektreten verantwortlich.