Photovoltaic Behavior Research Articles

Designing of banana shaped chromophores via molecular engineering of terminal groups to probe photovoltaic behavior of organic solar cell materials

To meet the rising requirement of photovoltaic compounds for modernized hi-tech purpose, we designed six new molecules (DTPD1-DTPD6) from banana shaped small fullerene free chromophore (DTPR) by structural tailoring at terminal acceptors. Frontier molecular orbitals (FMOs), density of states (DOS), open circuit voltage (Voc), transition density matrix (TDM) analysis, optical properties, reorganization energy value of hole and electron were determined utilizing density function theory (DFT) and time-dependent density function theory (TD-DFT) approaches, to analyze photovoltaic properties of said compounds. Band gap contraction (∆E = 2.717–2.167 eV) accompanied by larger bathochromic shift (λmax = 585.490–709.693 nm) was observed in derivatives contrary to DTPR. The FMOs, DOS and TDMs investigations explored that central acceptor moiety played significant role for charge transformation. The minimum binding energy values for DTPD1-DTPD6 demonstrated the higher exciton dissociation rate with greater charge transferal rate than DTPR, which was further endorsed by TDM and DOS analyses. A comparable Voc (1.49–2.535 V) with respect to the HOMOPBDBT–LUMOacceptor for entitled compounds was investigated. In a nutshell, all the tailored chromophores can be considered as highly efficient compounds for promising OSCs with a good Voc response.

Technico and Economic Optimization of the Injection of a Photovoltaic System on a Low Voltage Network

AbstractThis paper investigates an experimental study of photovoltaic PV modules behavior (SM110-24) connected to the low-voltage grid (230 V / 50 Hz) with a three-phase inverter. In order to ensure maximum power point tracking (MPPT), The input voltage is delivered via a DC/DC converter that is controlled by the Fuzzy Logic Technical FLC to ensure maximum power MPPT. The control system of the setup is designed for the extraction of maximum power. The primary aim of this investigation is to synchronize the two sources namely PV-grid, using the Phase Locked Loop PLL command with the injection of an alternating current into the network whose aim is stabilizing the system and minimizing the cost of the energy consumed by the load. In this study, the authors have taken into account the real kWh price of the Algerian society of distribution of electricity (Sonelgaz) as the basis for their research. The simulation results obtained by utilizing the MATLAB software show that the proposed system exhibits high performance and flexibility, indicating its potential usefulness for practical applications in the future.

Bulk Photovoltaic Effect in Two-Dimensional Distorted MoTe2.

In future solar cell technologies, the thermodynamic Shockley-Queisser limit for solar-to-current conversion in traditional p-n junctions could potentially be overcome with a bulk photovoltaic effect by creating an inversion broken symmetry in piezoelectric or ferroelectric materials. Here, we unveiled mechanical distortion-induced bulk photovoltaic behavior in a two-dimensional (2D) material, MoTe2, caused by the phase transition and broken inversion symmetry in MoTe2. The phase transition from single-crystalline semiconducting 2H-MoTe2 to semimetallic 1T'-MoTe2 was confirmed using X-ray photoelectron spectroscopy (XPS). We used a micrometer-scale system to measure the absorption of energy, which reduced from 800 to 63 meV during phase transformation from hexagonal to distorted octahedral and revealed a smaller bandgap semimetallic behavior. Experimentally, a large bulk photovoltaic response is anticipated with the maximum photovoltage VOC = 16 mV and a positive signal of the ISC = 60 μA (400 nm, 90.4 Wcm-2) in the absence of an external electric field. The maximum values of both R and EQE were found to be 98 mAW-1 and 30%, respectively. Our findings are distinctive features of the photocurrent responses caused by in-plane polarity and its potential from a wide pool of established TMD-based nanomaterials and a cutting-edge approach to optimize the efficiency in converting photons-to-electricity for power harvesting optoelectronics devices.

Formation and Characterization of Stable TiO2/CuxO-Based Solar Cells.

According to increasing demand for energy, PV cells seem to be one of the best answers for human needs. Considering features such as availability, low production costs, high stability, etc., metal oxide semiconductors (MOS) are a focus of attention for many scientists. Amongst MOS, TiO2 and CuxO seem to be promising materials for obtaining an effective photoconversion effect. In this paper, specific investigation, aimed at the manufacturing of the complete photovoltaic structure based on this concept is described in detail. A set of samples manufactured by DC magnetron sputtering, with various process parameters, is characterized by morphology comparison, layer structure and material composition investigation, and finally by the obtained photovoltaic parameters. Based on SEM studies, it was established that the films are deposited uniformly and complete their formation; without clearly defined faces, the conglomerates of the film grow individually. These are areas with a uniform structure and orientation of atoms. The sizes of conglomerates are in a normal direction range from 20 to 530 nm and increase with film thickness. The film thickness was in the range from 318 to 1654 nm, respectively. The I-V study confirms the photovoltaic behavior of thin film solar cells. The open-circuit voltage (Voc) and short-circuit current density (Jsc) values of the photovoltaic devices ranged from 1.5 to 300 mV and from 0.45 to 7.26 µA/cm3, respectively, which corresponds to the maximum efficiency at the level of 0.01%. Specific analysis of the junction operation on the basis of characteristics flow, Rs, and Rsh values is delivered.

Structural modeling of 1,4 azaborine-based chromophores for organic solar cells using bracing units with benzothiophene-incorporated acceptors for exploration of photovoltaic behavior

Non-fullerene (NF) compounds are currently being studied for potential use in organicsolar cellsand sustainable energy sources. Herein, a series of NF acceptor chromophores (CMP1-CMP7) with 1,4 azaborine central unit was fabricated via structural modulation of CMPR through redistribution of benzothiophene-incorporated terminal acceptors. Various DFT investigations such as frontier molecular orbitals (FMOs), density of states (DOS), transition density matrix (TDM), binding energy (Eb), UV–Visible and electron hole analyses were completed at MPW1PW91/6-311G (d,p) level to analyze photovoltaic properties of designed chromophores. All the designed compounds had a maximum absorption wavelength (λmax) of 679.74–718.67 nm with reduced bandgap of 2.29–2.17 eV, as compared to CMPR chromophore (Egap = 2.32 eV and λmax = 666.40 nm). Moreover, all derivatives except CMP1 (0.46 eV) shownless Eb (0.44–0.46 eV) than CMPR (0.46 eV). These lower binding energies of CMP2-CMP7 allow rapidexcitation dissociationthan CMPR, leading to the production of free charge carriers that was also supplemented by DOS as well as TDM investigations. Additionally, open circuit voltage (Voc) investigation was executed relative to HOMOJ52Cl-LUMOacceptor, and all the designed chromophores displayed an analogous voltage value with that of CMPR. The GRP outcomes are correlated with the energy gap values and depicted higher softness values. Interestingly, CMP7 was proven to be the best optoelectronic material demonstrating auspicious photovoltaic properties including the smallest bandgap (2.16 eV), maximum λmax value (718.67 nm) in chloroform, lowest excitation energy (1.73 eV) and Eb value (0.44 eV). The results demonstrated that the end-capped modification with benzothiophene acceptors was proved to be an influential approach in acquiring desirable photovoltaic characteristics.

Van der Waals semiconductor based self-powered transparent broadband photodetector

Van der Waals (vdW) semiconductors have attracted significant research interest owing to their tunable electrical and optical properties. The thin layer structure and high optical transparency of vdW semiconductors make them suitable for use in transparent optoelectronics. Broadband and transparent photodetection are crucial requirements for the development of next-generation optoelectronics. In this study, we fabricate a self-powered transparent photodetector consisting of a vdW semiconductor (SnS) and a wide-bandgap oxide (Ga2O3) thin film. The device is transparent, exhibiting average visible transmittance of 45%. The self-biased transparent photodetector showed a photovoltaic behavior under illumination, with a significant open circuit voltage of 496 mV and a considerably high short-circuit current density of 1.7 mA/cm2. The device exhibited a significant photoresponse under UV (340 nm) to NIR (850 nm) illumination. Moreover, it showed a remarkable responsivity of 210.4 mA/W and the fastest response time of ∼8 ms, making it a self-operated broadband transparent photodetector.

Advanced Characterization of 1 eV GaInAs Inverted Metamorphic Solar Cells

In this work, 1 eV Ga0.7In0.3As inverted metamorphic (IMM) solar cells were analyzed to achieve a deeper understanding of the mechanism limiting their improvement. For this purpose, high-resolution X-ray diffraction (HRXRD), transmission electron microscopy (TEM), high-resolution cross-sectional cathodoluminescence (CL), and transient in situ surface reflectance were carried out. Additionally, the photovoltaic responses of the complete devices were measured using the external quantum efficiency (EQE) and numerically simulated through Silvaco TCAD ATLAS. The combination of structural characterization of the semiconductor layers and measurements of the solar cell photovoltaic behavior, together with device modeling, allows us to conclude that the lifetime of the bulk minority carriers is the limiting factor influencing the PV response since the recombination at the interfaces (GaInP window–GaInAs emitter and GaInAs base–GaInP back surface field (BSF)) does not impact the carrier recombination due to the favorable alignment between the conduction and the valance bands. The advanced characterization using cross-sectional cathodoluminescence, together with transient in situ surface reflectance, allowed the rejection of the formation of traps related to the GaInAs growth conditions as being responsible for the decrement in the minority-carrier lifetime. Conversely, the TEM and HRXRD revealed that the presence of misfit dislocations in the GaInAs layer linked to strain relaxation, which were probably formed due to an excessive tensile strain in the virtual substrate or an incorrect combination of alloy compositions in the topmost layers, was the dominant factor influencing the GaInAs layer’s quality. These results allow an understanding of the contributions of each characterization technique in the analysis of multi-junction solar cells.

Highly Efficient Van Der Waals Heterojunction on Graphdiyne toward the High-Performance Photodetector.

Graphdiyne (GDY), a new 2D material, has recently proven excellent performance in photodetector applications due toits direct bandgap and high mobility. Different from the zero-gap of graphene, these preeminent properties made GDY emerge as a rising star for solving the bottleneck of graphene-based inefficient heterojunction. Herein, a highly effective graphdiyne/molybdenum (GDY/MoS2 ) type-II heterojunction in a charge separation is reported toward a high-performance photodetector. Characterized by robust electron repulsion of alkyne-rich skeleton, the GDY based junction facilitates the effective electron-hole pairs separation and transfer. This results in significant suppression of Auger recombination up to six times at the GDY/MoS2 interface compared with the pristine materials owing to an ultrafast hot hole transfer from MoS2 to GDY. GDY/MoS2 device demonstrates notable photovoltaic behavior with a short-circuit current of -1.3 × 10-5 A and a large open-circuit voltage of 0.23V under visible irradiation. As a positive-charge-attracting magnet, under illumination, alkyne-rich framework induces positive photogating effect on the neighboring MoS2 , further enhancing photocurrent. Consequently, the device exhibits broadband detection (453-1064nm) with a maximum responsivity of 78.5 A W-1 and a high speed of 50 µs. Results open up a new promising strategy using GDY toward effective junction for future optoelectronic applications.

Impact of A‐Site Cation Modification on Charge Transport Properties of Lead Halide Perovskite for Photovoltaics Applications

Perovskite solar cells (PSCs) have reached a formidable power conversion efficiency of 25.7% over the years of development. One of the strategies that has been responsible for the development of stable and highly efficient PSCs is modifications of the monovalent A‐site cations (methylammonium, MA; formamidinium, FA; cesium, Cs, etc.) in lead halide perovskites. Herein, the impact of modifying the monovalent cation (MA, FAMA, CsFAMA, potassium‐passivated CsFAMA, rubidium‐passivated CsFAMA) in lead halide perovskite on their optoelectronic, charge transport, and photovoltaic behavior is systematically studied. Reduced trap density and improved charge carrier mobility after introduction of FA and Cs in the MAPb(I0.85Br0.15)3 system are confirmed. Further passivation of the triple‐cation perovskite with K and Rb enhances the optoelectronic characteristics, charge transport, and charge extraction efficiency in halide perovskite solar cells.

Niobium-doped NiO as p-type nanostructured layer for transparent photovoltaics

Niobium-doped nickel oxide (NiO:Nb) thin films were investigated as p-type layer for all oxide transparent solar cells. The NiO:Nb films were grown by sputtering on room-temperature substrates in plasma containing 50% Ar and 50% O2 gases. The undoped NiO film was oxygen-rich, single-phase cubic NiO, exhibiting transmittance of less than 20%. Upon doping with Nb, the film remained p-type, the hole concentration increased from 4.3 × 1018 cm−3 to 1.2 × 1019 cm−3 but the optical properties remained almost the same with the undoped film. The changes in the properties of the films such as structural disorder, energy band-gap, Urbach states and resistivity were correlated with the incorporation of Nb in their structure. Improvement of the optical properties was achieved by thermal treatment at 300 °C. The visible transmittance increased to around 50% and the films showed a direct band-gap of 3.65–3.71 eV depending on the amount of Nb in the Ni-O structure. The optimum p-NiO:Nb film was used to form a diode with a spin-coated, mesoporous on top of a compact, TiO2 film. The p-NiO:Nb/n-TiO2 heterojunction became transparent after thermal treatment, showing rectifying characteristics. The diode showed photovoltaic behavior upon illumination with ultraviolet light exhibiting short-circuit current density 1.5 μA/cm2 and open-circuit voltage 200 mV. Transparent NiO:Nb films can be realized for all-oxide ultraviolet photovoltaics, tandem solar cells, solar-blind photodetectors and other optoelectronic devices.

Metal‐free Organic Dyes Featuring an Azobenzene Bridge for Photochromic Dye‐Sensitized Solar Cells

AbstractWe report the facile synthesis of photochromic donor‐π‐acceptor (D‐π‐A) dyes featuring an azobenzene spacer with diphenylamine and dimethylamine as donor residues (DPAC and DMAC). We also investigate the spectroscopic and electrochemical properties of these dyes and their application to dye‐sensitized solar cells (DSSCs). The trans‐cis isomerization of the azobenzene bridge permits regulation of the photovoltaic behaviour in the DSSCs containing iodine‐ and cobalt‐based redox electrolytes. The iodidie/triiodidie redox shuttle is suitable for DMAC‐DSSCs, whereas the cobalt redox mediator is optimal for DPAC‐DSSCs. DMAC‐ and DPAC‐DSSCs yield power conversion efficiencies (PCEs) up to 1.99 % and 1.08 % under one sun illumination, when the solar cells are at the photostationary (PS) state.

Insight into structural, optical, electrical, dielectric, and photovoltaic behaviour of cerium-doped strontium titanate by a modified combustion method

Insight into structural, optical, electrical, dielectric, and photovoltaic behaviour of cerium-doped strontium titanate by a modified combustion method

Ferroelectrically Modulated and Enhanced Photoresponse in a Self-Powered α-In2Se3/Si Heterojunction Photodetector.

Photodetectors have been applied to pivotal optoelectronic components of modern optical communication, sensing, and imaging systems. As a room-temperature ferroelectric van der Waals semiconductor, 2D α-In2Se3 is a promising candidate for a next-generation optoelectronic material because of its thickness-dependent direct bandgap and excellent optoelectronic performance. Previous studies of photodetectors based on α-In2Se3 have been rarely focused on the modulated relationship between the α-In2Se3 intrinsic ferroelectricity and photoresponsivity. Herein, a simple integrated process and high-performance photodetector based on an α-In2Se3/Si vertical hybrid-dimensional heterojunction was constructed. Our photodetector in the ferroelectric polarization up state accomplishes a self-powered, highly sensitive photoresponse with an on/off ratio of 4.5 × 105 and detectivity of 1.6 × 1013 Jones, and it also shows a fast response time with 43 μs. The depolarization field generated by the remanent polarization of ferroelectrics in α-In2Se3 provides a strategy for enhancement and modulation of photodetection. The negative correlation was discovered because the enhancement photoresponsivity factor of ferroelectric modulation competes with the photovoltaic behavior within the α-In2Se3/Si heterojunction. Our research highlights the great potential of the high-efficiency heterojunction photodetector for future object recognition and photoelectric imaging.

Enhancing the Photovoltaic Properties via Incorporation of Selenophene Units in Organic Chromophores with A2-π2-A1-π1-A2 Configuration: A DFT-Based Exploration

Currently, polymer organic solar cells (POSCs) are widely utilized due to their significant application, such as low-cost power conversion efficiencies (PCEs). Therefore, we designed a series of photovoltaic materials (D1, D2, D3, D5 and D7) by the incorporation of selenophene units (n = 1-7) as π1-spacers by considering the importance of POSCs. Density functional theory (DFT) calculations were accomplished at MPW1PW91/6-311G (d, p) functional to explore the impact of additional selenophene units on the photovoltaic behavior of the above-mentioned compounds. A comparative analysis was conducted for designed compounds and reference compounds (D1). Reduction in energy gaps (∆E = 2.399 - 2.064 eV) with broader absorption wavelength (λmax = 655.480 - 728.376 nm) in chloroform along with larger charge transference rate was studied with the addition of selenophene units as compared to D1. A significantly higher exciton dissociation rate was studied as lower values of binding energy (Eb = 0.508 - 0.362 eV) were noted in derivatives than in the reference (Eb = 0.526 eV). Moreover, transition density matrix (TDM) and density of state (DOS) data also supported the efficient charge transition origination from HOMOs to LUMOs. Open circuit voltage (Voc) was also calculated for all the aforesaid compounds to check the efficiency, and significant results were seen (1.633-1.549 V). All the analyses supported our compounds as efficient POSCs materials with significant efficacy. These compounds might encourage the experimental researchers to synthesize them due to proficient photovoltaic materials.

Exploration of photovoltaic behavior of benzodithiophene based non-fullerene chromophores: first theoretical framework for highly efficient photovoltaic parameters

Keeping in view, the recent energy conditions and contribution of non-fullerene acceptors (NFAs) towards organic solar cells (OSCs), a series of NFAs (D1-D9) was designed. The novel fused ring NFAs (D1-D9) having A-D-A architecture were designed by structural engineering of R molecule with effective benzothiophene based acceptor moieties. For current study, all the calculations were accomplished at M06/6-311G (d,p) level. Different computational approaches like density of states (DOS), binding energy (Eb), transition density matrix (TDM), absorption spectra (UV–Vis), electronic properties (FMOs) and open circuit were performed to investigate the photovoltaic response of newly designed D1-D9 chromophores. The terminal substitution of end-capped acceptors exhibited a reduction in energy gap (ΔE = 2.222–1.986 eV) with high electron mobility rate in all the derivatives (D1-D9) than that of R. All the designed chromophores exhibited wider absorption spectrum (λmax = 845.039–786.552 nm) along with lower excitation energy as compared to R (λmax = 770.040 nm) except D1 and D9. Interestingly, lower binding energy (Eb = 0.419–0.473 eV) accompanying with higher excition dissociation rate was seen in derivatives than that of reference compound. Moreover, a comparable value of Voc was noted in derivatives when calculated via LUMOacceptor–HOMOPBDBT. Among all fore-said chromophores (D1-D9), D4 exhibited lowest binding energy and thus ensured easier and faster excition dissociation rate along with highest Voc (1.586 V). In cessation, this structural modification by utilizing various acceptors played a significant role in obtaining auspicious photovoltaic response in compounds. Hence, our study encourages the experimentalists for synthesizing these proposed organic systems for the attaining high efficacy photovoltaic devices.

A controllable conduction-type photovoltaic effect in MoTe2

In this study, we unveiled that a conduction type can be controlled from the 2H-MoTe2 ambipolar semiconducting phase to the selective opposite n-type or p-type FETs. The polarity inversion has been achieved through the trapped interface states that exist between h-BN and SiO2 upon illumination with an external gate voltage. For the n-type doping effect, we found that it has a positive coefficient with the thickness of h-BN but the p-type doping was not achieved with a thickness of 50 nm or beyond. For the n-type MoTe2 FET, the carrier concentration n(n−MoTe2) and mobility μ(n−MoTe2) were calculated to be ∼2.07 × 1012 cm−2 and ∼20.17 cm2/V/s, respectively, while for the p-type FET n(p−MoTe2) and μ(p−MoTe2) are ∼2.16 × 1012 cm−2 and ∼24.04 cm2/V/s, respectively. Moreover, we also develop a lateral PIN diode with an intrinsic region that was in-between n- and p-type FETs. An electrical performance was also monitored, and an ideal rectifying behavior was reached with a rectification ratio (IfIr) of almost >106. The PIN diode also exhibits a self-biased photovoltaic behavior with an open-circuit voltage (Voc = 440.9 mV). This research work may pave the way for fabricating photodiodes with low power consumption using transition metal dichalcogenides materials.

Revisiting the Ferroelectric Photovoltaic Properties of Vertical BiFeO3 Capacitors: A Comprehensive Study.

The ferroelectric photovoltaic effect has been extensively studied for possible applications in energy conversion and photo-electrics. The reversible spontaneous polarization gives rise to a switchable photovoltaic behavior. However, despite its long history, the origin of the ferroelectric photovoltaic effect still lacks a full understanding since multiple mechanisms such as bulk and Schottky-barrier-related interface effects are involved. Herein, we report a comprehensive study on the photovoltaic response of BiFeO3-based vertical heterostructures, using multiple strategies to clarify its origin. We found that, under white light illumination, polarization-modulated Schottky barrier at the interface is the dominating mechanism. By varying the top metal contacts, only the photovoltaic effect of the polarization downward state is strongly modulated, suggesting selective interface contribution in different polarization states. A Schottky-barrier-free device shows negligible photovoltaic effect, suggesting the lack of bulk photovoltaic effect in vertical heterostructures under white light illumination.

Exploration of photovoltaic behavior of fused triphenylamine moiety as core donor with modified acceptors: Star-shaped D-[formula omitted]-A conjugated systems

Fullerene-free organic chromophores have drawn considerable attention as successful photonic devices for organic solar cells. So, a series of novel non-fullerene-based donor molecules (HBTD2–HBTD9) were fabricated via structural modification of the terminal acceptor groups from HBTR1. In order to achieve the photovoltaic, photophysical, and electronic behavior of fore-said compounds, density functional theory/time-dependent density functional theory (DFT/TD-DFT) based analyses were accomplished at B3LYP functional along with 6-311G(d,p) basis set. The optical and electrical characteristics of the derivatives were compared with HBTR1 architecture. All designed molecules exhibited a lower EHOMO-ELUMO band gap (2.183–4.106 eV) with a red shift in absorbance compared to the reference compound (4.179 eV). All derivatives (HBTD2–HBTD9), except HBTD3, showed a greater exciton dissociation rate due to low binding energy (Eb = −0.337 to 1.400 eV) when compared with HBTR1 (Eb = 1.401 eV). Interestingly, HBTD9 manifested to be the prime candidate for non-fullerene organic solar cells (NF–OSCs) owing to the lowest energy band gap, large mobility of charges, and least value of binding energy while holding an excellent redshift value compared to all the designed chromophores. This study revealed that these chromophores would be potential competitors in manufacturing effective optoelectronic materials.

A fast and precise double-diode model for predicting photovoltaic panel electrical behavior in variable environmental conditions

A precise understanding of photovoltaic output behaviour leads to better organising of investment resources and more efficient development planning. Besides under standard test conditions, the presented model can predict the output of a photovoltaic module under variable real-time situations. The proposed hybrid analytical-numerical method declined the calculation and running time while offering an acceptable predicting accuracy. Models’ predictions were validated with the information reported by the manufacturer and experimental analysis and real-time measurements. The dust impacts were also investigated. The model accuracy was compared with a single diode model under the same conditions and several other similar works. Finally, the model was used to investigate the effect of any variation in cell temperature and irradiation levels on the output of photovoltaic modules. The proposed hybrid model can be a benchmark for future studies. It can be modified and developed to foresee the electrical output of a photovoltaic system in other regions if the system specifications and weather conditions and diversities are applied accordingly.

Two-dimensional hybrid perovskite resistive switching memory inherited from photovoltaic devices

Ions or charged vacancies drift induced by electric fields in organic–inorganic halide perovskites (OIHPs) generally contributes to distinct current–voltage hysteresis, which drives the development of resistive switching memory (RSM) devices. Here, the two-dimensional (2D) OIHP films are adopted as the switching layer to fabricate the RSM devices with a simplified photovoltaic structure. The device displays stable and low voltage resistive switching (RS) characteristics, with an on/off ratio greater than 106 and a switching voltage as low as 0.4 V. After adding a NiOx hole transport layer in a completed photovoltaic device, the fabricated RSM devices without encapsulation show reliable RS behavior with an endurance over 4 × 102 cycles and a retention time of 103 s in atmospheric conditions. Both Ag ions and iodine vacancies conductive filaments are responsible for the RS properties. This work provides a perspective for appvlication in high-performance 2D OIHP RSM devices compatible with photovoltaic behavior.