In this work, we present a theoretical investigation of electron-surface optical phonon (SOP) interactions and Auger recombination processes in monolayer PtSe2 and PtS2 supported on polar dielectric substrates such as SiO2 and hBN. The analysis is based on a low-energy effective Hamiltonian describing the electronic structure near the K and K' valleys of the Brillouin zone, combined with the Fröhlich interaction model to account for the coupling between charge carriers and substrate-induced optical phonons. The comparison between Auger recombination and SOP scattering is performed at a representative carrier density of n=1012 cm-2 within the investigated temperature range. We analyze the formation of polaronic states arising from the hybridization between electronic excitations and SOPs and evaluate the associated Rabi splitting energies and oscillator strengths. The temperature dependence of the SOP-induced scattering rates and the influence of the monolayer-substrate separation on carrier-phonon interactions are also examined. Our results show that electron-phonon coupling strongly depends on the dielectric properties of the supporting substrate, with larger anticrossing gaps predicted for hBN-supported structures compared with SiO2-supported systems. Auger recombination constitutes the dominant carrier relaxation channel within the investigated temperature range, whereas SOP scattering becomes increasingly significant at elevated temperatures, where both mechanisms approach a comparable inelastic phonon-limited regime. These findings highlight the role of dielectric engineering in controlling carrier relaxation dynamics in Pt-based TMDC heterostructures.

We perform a theoretical investigation of the electron–surface optical phonon (SOP) interaction in Van der Waals heterostructures (vdWHs) formed by monolayer graphene (1LG) and transition metal dichalcogenides (TMDCs), using eigenenergies obtained from the tight-binding Hamiltonian for electrons. Our analysis reveals that the SOP interaction strength strongly depends on the specific TMDC material. TMDC layers generate localized SOP modes near the 1LG/TMDC interface, serving as effective scattering centers for graphene carriers through long-range Fröhlich coupling. This interaction leads to resonant coupling of electronic sub-levels with SOP, resulting in Rabi splitting of the electronon energy levels. We further explore the influence of different TMDCs, such as WS2, WSe2, MoS2, and MoSe2, on transport properties such as SOP-limited mobility, resistivity, conductivity, and scattering rates across various temperatures and charge carrier densities. Our analysis confirms that at elevated temperatures and low carrier densities, surface optical phonon scattering becomes a dominant factor in determining resistivity. Additionally, we investigate the Auger recombination process at the 1LG/TMDC interface, showing that both Auger and SOP scattering rates increase significantly at room temperature and higher, ultimately converging to constant values as the temperature rises. In contrast, their impact is minimal at lower temperatures. These results highlight the potential of 1LG/TMDC-based vdWHs for controlling key processes, such as SOP interactions and Auger recombination, paving the way for high-performance nanoelectronic and optoelectronic devices.

Bulk heterojunction organic solar cells made of poly(3-hexylthiophene) and 6,6-phenyl C61-butyric acid methyl ester and covered by multilayer antireflection coatings are investigated using an improved analytical optoelectronic model. The model utilizes both optical transfer matrix method and drift-diffusion equations, and it incorporates the effect of incoherent light transmission through the thick glass substrate. The influence of the multilayer antireflection coating on electromagnetic radiation propagating throughout the layered structure is studied by calculating the position-dependent charge-carrier generation rates. Dark and photocurrents are calculated by considering the first-order carrier recombination and by solving the continuity equations for electrons and holes. Justification of the improved model is achieved by comparing the obtained results with published experimental datasets from independent studies. A modified expression for exciton generation rate that includes an empirical term of sinusoidal functions is used, thus better simulating the published data. Using our improved model, good agreements are obtained between the modeled current-voltage characteristics and the measurements for different light intensities (A.M1.5G) while having an electron-to-hole mobility ratio below the limit of 50 as reported in the literature. An optimization method for plotting figures-of-merits characteristics of coated devices, which are useful to design efficient multilayer antireflection coatings and to estimate the device performance improvements, is also proposed. This optimization was successfully performed to material films adequate to antireflective applications. An improvement in the power conversion efficiency about 4.5% for active layer thickness of 90 nm is reached by using MgF2/ZrO2/MgO material films in quarter-half-quarter configuration as a multilayer antireflection coating. This coating is more efficient for active layer of 215 nm thickness showing an improvement of 5.4% in the power conversion efficiency.

We theoretically investigated the electron–surface optical phonon interaction across the long-range Fröhlich coupling in monolayer transition metal dichalcogenides, such as WS2, WSe2, MoS2, and MoSe2 monolayers, on SiC and hexagonal BN dielectric substrates. We employed the effective Hamiltonian in the K+(K−) valley of the hexagonal Brillouin zone to assess the electronic energy shifts induced by the interaction between electronic states and surface polar optical phonons. Our results indicate that the interaction between electrons and surface optical phonons depends upon the polar nature of the substrate. We have also calculated the polaronic oscillator strength, as well as the polaronic scattering rate of the lower polaron state in monolayer WS2, WSe2, MoS2, and MoSe2 on SiC and hexagonal BN dielectric substrates. As a result, we have theoretically proved the following: firstly, the enhancement of the polaronic scattering rate with temperature, and secondly, the notable influence of the careful selection of surrounding dielectrics on both the polaronic oscillator strength and the polaronic scattering rate. Thus, optimal dielectrics would be those exhibiting both elevated optical phonon energy and a high static dielectric constant.

The reflection losses are among the principal causes that limiting the performances of the solar cells. Indeed, the conventional organic solar cell (OSC) provides a relatively low photocurrent mainly due to light reflection at the front and back sides of the glass-substrate. To overcome this limitation we propose an optimized hybrid antireflective structure. The proposed design is a combination between multilayer antireflection coating (MARC) and moth eye structure (MES). The OSC with this antireflection coating, consisting of thin coherent multilayer stack and moth eye subwavelength structure, is modeled using transfer matrix method (TMM) and effective medium theory (EMT). In this work, several antireflection coating designs with different dielectric material films are investigated. The layer thicknesses of the MARC were tuned such that they obey to quarter-quarter-quarter (Q-Q-Q) and quarter-half-quarter (Q-H-Q) wavelength rules to obtain zero reflectance. Based on these configurations, we performed an optimization algorithm to design the antireflection coating that maximizes the short circuit photocurrent density (JSC). The optical analysis is applied to ITO/PEDOT:PSS/P3HT:PCBM/Al bulk heterojunction (BHJ) organic solar cell. The highest value of short circuit photocurrent density is obtained for OSC with hybrid MES/Glass-substrate/MARC(QHQ) antireflective structure using Al2O3/ZrO2/M-optm material films. In comparison with the conventional organic solar cell without antireflection coating, the short circuit photocurrent density was improved by 5% at normal incidence. Besides, the antireflection effect is maintained even at large incidence angle of 68° thanks to the omnidirectional optical propriety of the moth eye structure.

The electron-spin duality and propagation of the active sites of free electrons are of interest for adsorbing the guests and fixing them with strong hydrogen bonds (HB). The coherence of the systems with the guests is one of the main parameters that favor the experimentation of new systems on primary column adsorption phenomena. The stability and the adaptable symmetries in all directions justify the use of a "nanocage" (ZnO) for studying adsorption phenomena. The formation of stable electronic charge transfer paths between sites occupied by very stable atomic orbitals ensures the success of the adsorption of the ligands. Electronic characterization (MES, FMO, DOS, and cationic doping) is used to describe the movement of the intra-Cu-Co/Zn19O20 electrons. The phenomena of charge transfer, stability, types of orbital occupations, adsorption sites, electron migration direction, conductivity, and reactivity of such systems are thoroughly explored. Based on these findings, the efficiency of a Cu-Co/Zn19O20 nanocage to adsorb three different ligands (medical ligands, prostate biomarkers, and antibiotics) is studied. From the reactivity parameter discussions, it is found that the copper or cobalt-doped nanocage-Citric Acid has a strongly electronegative index (4.40 eV and 4.91 eV) and hardness (1.99 eV and 1.82 eV) properties. The Fourier transform infrared analyses and orbital localizations (& alpha; and & beta;) clearly demonstrate that the charge transfer occurs inter-surface, from nanocages to adsorbed ligands. Bader's theory analysis for the adsorption ligands VA (Vinyl Alcohol), CA (Citric Acid), and SMX (Sulfamethoxazole) by the doped copper and cobalt nanocages demonstrates that these systems are much more adequate for adsorbing the ligand antibiotics than the other hosts. The highly adsorbent energy of sulfamethoxazole by Cu-Zn19O20 is equal to-582.86 kJ. mol-1. The IGM-NCI/ELF analyses support these findings, revealing that the Cu/Co-Zn19O20 nanocages adsorb SMX via hydrogen bonding and van der Waals interactions, as they also did in DFT-D3 and FT-IR analyses. LOL analyses support this claim by visualizing single-pair spins in excess surrounding acceptor atoms (O) in the two systems. Molecular dynamics simulations show that SMX is quickly adsorbed by nanocages of Zn19O20 doped with copper (d9) or cobalt (d7).

The spin-electron duality and propagation of the active sites of free electrons are of interest for adsorbing the guests and fixing them with strong hydrogen bonds (HB). The coherence of the systems with the guests is one of the main parameters that favor the experimentation of new systems on primary column adsorption phenomena. The stability and the adaptable symmetries in all directions justify the use of a "nanocage" (ZnO) for studying adsorption phenomena. The formation of stable electronic charge transfer paths between sites occupied by very stable atomic orbitals ensures the success of the adsorption of the ligands. Electronic characterization (MES, FMO, DOS, cationic doping) is used to describe the movement of the intra-Cu-Co/Zn19O20 electrons. The phenomena of charge transfer, stability, types of orbital occupations, adsorption sites, electron migration direction, conductivity, and reactivity of such systems are thoroughly explored. Based on these findings, the efficiency of a Cu-Co/Zn19O20 nanocage to adsorb three different ligands (medical ligands, prostate biomarkers, and antibiotics) is studied. The phonic-vibrational analyses and orbital localizations (α and β) clearly demonstrate that the charge transfer occurs inter-surface, from nanocages to adsorbed ligands. Bader's theory analysis for the adsorption ligands VA (Vinyl Alcohol), CA (Citric Acid), and SMX (Sulfamethoxazole) by the doped copper and cobalt nanocages demonstrates that these systems are much more adequate for adsorbing the ligand antibiotics than the other hosts. The IGM-NCI/ELF analyses support these findings, revealing that the Cu/Co-Zn19O20 nanocages adsorb SMX via hydrogen and van der Waals interactions. LOL analyses support this claim by visualizing single-pair spins in excess surrounding acceptor atoms (O) in the two systems. Molecular dynamics simulations show that SMX is quickly adsorbed by nanocages of Zn19O20 doped with copper (d9) or cobalt (d7).

In this work, we present an analytical method based on three diode model to estimate the electrical parameters of the hybrid photovoltaic solar cells. The photovoltaic module is generally represented by an equivalent electrical circuit whose electrical parameters are determined experimentally using the current density -voltage (J -V) characteristic in dark and under illumination. The current-voltage characteristic obtained according to Kirchhoff's law applied to the equivalent circuit using to study the doped PEDOT: PSS/n-Si hybrid photovoltaic solar cells with various dimethyl sulfoxide (DMSO) concentration is resolved numerically by applying the Lambert W function. The parameters extracted which key parameters for the hybrid photovoltaic solar cells which are shunt resistance (Rs), series resistance (Rsh), ideality factors (n1, n2, n3), saturation current density Jsi (i = 1,2 and 3) and generated current density (Jph) are determined and compared with those calculated by the model. The results of numerical simulations which have been obtained show a good agreement with the experimental electrical characterizations results.

The electrical properties of dinaphtho [2,3-b:2 ',3 '-f]thieno[3,2-b]thiophene (DNTT) based organic thin film transistors (DNTT-TFTs) were investigated in detail under dark and various light illumination conditions with different channel lengths. We have exploited the experimental curves current-voltage of our TFT to extract electrical parameters such us mobility, threshold voltage, sub-threshold voltage and trapped density in dark and under illumination. By using an analytical model, we are able to reproduce very accurately the output and transfer characteristics with a joint analysis of the L = 100 mu m and L = 500 mu m electrical characteristics, the dependence of the contact resistance (R-c) upon the illumination conditions has been extracted. The used model gives a good agreement between the measured current-voltage characteristics of the DNTT-TFTs and those modeled in all measurement conditions (in dark and under illumination).

In this paper, we have study two types of thin-film organic transistors and their application to release the organic inverter. For manufacturing p-type and n-type organic thin film transistors (OTFT), pentacene and N,N'-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C13H27) have been used as organic semiconductors active layers. These organic thin film transistors have been shown excellent ambipolar operation. We proceeded initially to model and study these complementary organic transistors individually. Therefore we present the various electrical parameters resulting from the modeling of these two types of organic transistors (n-type and p-type) as well as the various parameters characterizing the organic inverter. Very good agreement is obtained between the experimental electrical characteristics of the two types of organic transistors and the characteristics obtained by the analytical model, as well as the experimental characteristics of the organic inverter thus produced.

Much research has been conducted to improve the performance of photovoltaic solar cells. Transparent conductive film and interconnection layers have a significant impact on the performance of photovoltaic cells. In this work, we analyze the experimental results obtained on tandem organic photovoltaic solar cells with simple inverted structures using silver nanowires AgNW as transparent conductive electrode (TE) and as interconnection layer (ICL) between PEDOT: PSS and ZnO. This type of contact leads to a strong ohmic contact in both sub-cells having P3HT: ICBA as the lower active layer and having PTB7: PC71BM (1: 1.5) as the upper active layer with a good complement of the absorption spectrum. To study the advantages of using AgNWs as an interconnection layer (PEDOT: PSS/AgNWs/ZnO) in tandem photovoltaic solar cells and as an anode and its impact on the performance of these organic cells, we have simulated the electrical characteristics obtained by these tandem organic photovoltaic cells using an equivalent circuit model. This model is based on a single diode model with five photovoltaic parameters. We therefore extracted all the physical parameters of the illuminated photovoltaic cell from its experimental characteristics (J–V), such as the diode saturation current density (J 0 ), the series and shunt resistors (R S , R Sh ), the ideality factor (n) and the photogenerated current density (J Ph ). For this we have solved the analytical equations of the current density using Newton Raphson's method. The equations are derived from the single diode equivalent circuit proposed to simulate the measured current density as a function of the voltage of the manufactured tandem type organic solar cells. A good agreement was obtained between the theoretical model and the experimental electrical characteristics. This confirms that the use of AgNWs between PEDOT: PSS and ZnO as an interconnection layer in reverse geometry of these tandem devices, has improved the efficiency (PCE = 9.24%) and is proving to be an efficient recombination layer for tandem organic photovoltaic solar cells.

In this work, we demonstrate P3HT (poly 3-hexylthiophene) organic rectifier diode both in rigid and flexible substrate with a rectification ratio up to 106. This performance has been achieved through tuning the work function of gold with a self-assembled monolayer of 2,3,4,5,6-pentafluorobenzenethiol (PFBT). The diode fabricated on flexible paper substrate shows a very good electrical stability under bending tests and the frequency response is estimated at more than 20 MHz which is sufficient for radio frequency identification (RFID) applications. It is also shown that the low operating voltage of this diode can be a real advantage for use in a rectenna for energy harvesting systems. Simulations of the diode structure show that it can be used at GSM and Wi-Fi frequencies if the diode capacitance is reduced to a few pF and its series resistance to a few hundred ohms. Under these conditions, the DC voltages generated by the rectenna can reach a value up to 1 V.

We have adapted a "peel-off" process to structure stacked organic semiconductors (conducting polymers or small molecules) and metal layers for diode microfabrication. The fabricated devices are organic diode rectifier in a coplanar waveguide structure. Unlike conventional lithographic process, this technique does not lead to destroy organic active layers since it does not involve harsh developer or any non-orthogonal solvent that alter the functionality of subsequentially deposited materials. This process also involves recently reported materials, as a p-dopant of an organometallic electron-acceptor Copper (II) trifluoromethanesulfonate, that play the role of hole injection layer in order to enhance the performances of the diode. Comparatively to self-assembled monolayers based optimized structures, the fabricated diodes show higher reproducibility and stability. High rectification ratio for realized pentacene and poly (3-hexylthiophene) diodes up to 106 has been achieved. Their high frequency response has been evaluated by performing theoretical simulations. The results predict operating frequencies of 200 MHz and 50 MHz for pentacene and P3HT diode rectifiers respectively, with an input oscillating voltage of 2 V peak-to-peak, promising for RFID device applications or for GSM band energy harvesting in low-cost IoT objects.

This paper presents recent progress in computational modeling on blend morphology of silicon nanowires (SiNWs) dispersed in a conjugated polymer poly(3-hexylthiophene) P3HT hybrid solar cells. Mixtures of poly-(3-hexyl-thiophene) as electron-donor and silicon nanowires as electron-acceptor materials have been widely investigated. In this work, we extracted five parameters such as the ideality factor, the saturation current, the photocurrent, the series and the shunt resistances from measured current–voltage characteristics. These parameters are used in the simulation study to obtain the theoretical curves by using the Newton-Raphson method developed in MATLAB code. A good agreement is obtained between theoretical model and experimental measurement of electrical characteristics. Taking the advantage of the simulation study, we determined the solar cell parameters to study the effect of SiNWs concentration, the type of solvent used for film fabrication and the thickness of photoactive layer in the performance of ITO/PEDOT:PSS/P3HT:SiNWs/Al hybrid solar cells in target to achieve the optimal condition: 15% of SiNWs dispersed within P3HT matrix fabricated from THF solution and 115 nm thickness photoactive layer with fill factor FF and efficiency η equal to 48% and 0.08%, respectively.

Simultaneously optimizing performances, processability and fabrication cost of organic electronic materials is the continual source of compromise hindering the development of disruptive applications. In this work, we identified a strategy to achieve record conductivity values of one of the most benchmarked semiconducting polymers by doping with an entirely solution-processed, water-free and cost-effective technique. High electrical conductivity for poly(3-hexylthiophene) up to 21 S/cm has been achieved, using a commercially available electron acceptor as both a Lewis acid and an oxidizing agent. While we managed water-free solution-processing a three-time higher conductivity for P3HT with a very affordable/available chemical, near-field microscopy reveals the existence of concentration-dependent higher-conductivity micro-domains for which furthermore process optimization might access to even higher performances. In the perpetual quest of reaching higher performances for organic electronics, this work shall greatly unlock applications maturation requiring higher-scale processability and lower fabrication costs concomitant of higher performances and new functionalities, in the current context where understanding the doping mechanism of such class of materials remains of the greatest interest.

Ternary zinc oxide/bismuth vanadate/three-dimensional ordered macroporous titanium dioxide (ZnO/BiVO4/3DOM TiO2) heterojuncted nanocomposites with cascade electronic band structures were successfully designed and synthesized for visible light photodegradation of two different molecules: Rhodamine B (RhB) and Tartrazine. The photocatalytic active species have been investigated by using electron scavenger (AgNO3) and hole scavenger (Triethanolamine: TEOA). The band edge positions of each component in tenary nanocomposites have been measured by using photoelectrochemical Mott-Schottky method and valence band XPS (VB-XPS) spectroscopy. Within the heterojunction, charges are favorably and spatially separated through the gradient potential at the interfaces. This largely suppresses the recombination of photogenerated electrons and holes. Furthermore, 3DOM inverse opal structure is beneficial for high diffusion efficiency and highly accessible surface area of reactants and light and multiple scattering for light harvesting. Consequently, these heterojuncted nanocomposites exhibit highly enhanced photocatalytic performance compared with pure BiVO4 nanostructure, and binary BiVO4/3DOM TiO2, ZnO/BiVO4 nanocomposites. A detailed mechanism of charge transfer is proposed for these ternary ZnO/BiVO4/3DOM TiO2 nanocomposites on the basis of a large series of spectroscopic and photocatalytic results. Our work demonstrates clearly that coupling multicomponent semiconductors with different energy levels of conduction and valence bands can significantly increase the photogenerated charge carriers through the efficient charge separation across their multiple interfaces. This work gives some new ideas on developing new visible light responsive nanocomposites for highly efficient solar energy utilization.

This chapter presents an up-to-date review of the several models commonly used to reproduce the current-voltage characteristics of the organic thin-film transistors (OTFTs). It features the different model formulations used for organic thin-film transistors. The chapter presents the derivation of the analytical expression of the drain current in the linear and saturation regimes by the systematic model that is currently used, which is called the Sze model. It describes the organic thin-film transistors have been theoretically studied and modeled, focusing particularly on the different analytical models of the electrical characteristics of the devices. The chapter introduces the general standard model that describes current-voltage equations in thin-film transistors, focusing on the geometry and properties of the active layer materials. It also examines a detailed description of the various manufacturing steps that we used to fabricate OTFTs as well as the electrical characterization step.

In this work, pentacene based thin film transistors (TFTs) with different channel lengths (L = 2.5, 5, 10 and 20 μm) have been fabricated and characterized electrically. Exploiting the electrical characteristics, we have analyzed the channel length effect on the key parameters of fabricated TFTs. We found that the performance of pentacene-TFTs was enormously enhanced by the reduction of channel length .We have also examined the influence of contact and channel resistances (RCandRch) on the electrical proprieties of fabricated TFTs, using the transmission line method (TLM). Then, we have modeled the dependence of the total resistanceRTon the gate voltageVGusing the grain boundary trapping Meyer–Neldel rule (GBT-MNR) model and we have successfully reproduced, the output characteristic of pentacene TFTs using the overall resistance extracted from the GBT-MNR model. Finally, in order to investigate the channel length effect on the dynamic behavior of fabricated devices, we have reported a dynamic model based on the quasistatic assumptions which were used for metal-oxide-semiconductor field-effect transistor (MOSFET). Accordingly, we have presented a simple small-signal equivalent circuit to calculate theoretically the capacitances of pentacene-TFTs for different channel lengths.