High-efficiency Devices Research Articles

Self-assembled molecular network with waterwheel-like architecture: experimental and theoretical evaluation toward electron transport capabilities for optoelectronic devices.

In recent times, self-assembled electron transport materials for optoelectronic devices, both solar cells and organic light-emitting diodes (OLEDs), have been gaining much interest as they help in fabricating high-efficiency devices. However, designing organic small molecular materials with star-shaped self-assembled networks is a challenge. To achieve this sort of target, we chose triazine and benzene-1,3,5-tricarbonyl cores for developing such architecture, and we developed four molecular systems, vizTCpCN, TCmCN, TmCN, and TpCN. Successful isolation of single crystals followed by structural analysis of TmCN revealed interesting molecular arrangements in the solid state resulting in the formation of a waterwheel type architecture with an extended network bearing characteristic voids. Theoretical calculations was carried out to check their electron transportability. The natural transition orbital calculation helped in understanding the locally excited and charge transfer excited states. The low electron reorganization energies of these molecules indicated that these materials may have potential to be used in electron transport layers of optoelectronic devices, particularly in OLEDs. Moreover, the assembled networks have a relatively wide surface area and linked structures, which are advantageous for the conduction of carriers with poor electron recombination inside the ETL, and these may offer a straightforward channel for electron conduction to the emissive layer. Finally, the fabricated electron-only device indicated that the synthesized materials may be used as ETMs in the electron transport layer of optoelectronic devices.

The mesa design guidance based on the effective range of the mesa sidewall reflector towards high-efficiency AlGaN-based DUV LEDs

AlGaN-based DUV LEDs show great application value and are currently confined by LEE. The mesa sidewall reflector is considered as an effective solution in enhancing LEE, but the extra LEE enhancement via reducing mesa size becomes not as significant if the mesa scale is already at low level. The specific mesa scale appropriate for light extraction is determined by effect decay process of the mesa sidewall reflector, which is studied and clarified in this work. By raytracing simulation, the decay length and the effective range of the reflector are estimated to be 20–25 μm and 40–50 μm, respectively. Devices with the mesa structures that separate the optical and electrical effects are fabricated, and the results validate the conclusions from the simulations. The mesa design guidance according to the reflector effective range, as well as the LEE enhancement potential of the designed mesa structure, is revealed to achieve high-efficiency DUV LED devices.

Design, optimization and enhancement of power conversion efficiency exceeding 30% for lead-free all-inorganic double perovskite-based solar cells using dual active layers

Here, we present a comprehensive simulation study focused on the design and optimization of power conversion efficiency (η) for lead-free, all-inorganic double perovskite-based solar cell (DPSC) device using SCAPS 1D. A non-toxic halide double perovskite layer, Cs2AgSb0.25Bi0.75Br6 is employed as absorber layer in designed solar cell along with various electron transport layers like ZnO, TiO2, C60, PCBM, IGZO and hole transport layers including NiO, Cu2O, MoO3, CuI, spiro-OMeTAD in n-i-p heterostructure configuration, aiming to achieve eco-friendly device with optimized efficiency and enhanced stability. The optimal configuration, FTO/C60/ Cs2AgSb0.25Bi0.75Br6/Cu2O/C, achieves a η ∼ 25.32% with Voc ∼ 1.58 V, Jsc ∼ 17.48 mA/cm2 and FF ∼ 91.4%. To further enhance the device performance, double active layers combining CsSnCl3 (band gap ∼ 1.52 eV) and Cs2AgSb0.25Bi0.75Br6 (band gap ∼ 1.80 eV) are introduced into the optimized device to leverage optical absorption for wide range of solar spectrum due to the graded optical band gap. Consequently, the power conversion efficiency of the cell elevated to ∼ 32.23% accompanied by Voc ∼ 1.36 V, Jsc ∼ 26.34 mA/cm2 and FF ∼ 90.3%, with a promise of creating high-efficiency solar cell devices, driving substantial progress in green energy technology.

(Invited) Effect of Seed Crystal Orientation on Ammonothermal Growth of GaN

Gallium nitride (GaN) is a wide bandgap semiconductor which has received widespread attention as it has enabled the development of short wavelength (UV, blue) optical emitters and promises a new generation of high efficiency power electronic devices. To enable widespread use of high power, high efficiency devices, the availability of large-area, inexpensive, low-defect-density GaN substrates is necessary.The ammonothermal method is a bulk, single crystal growth method which has demonstrated growth of high structural quality GaN boules greater than 2 inches in diameter. Despite these demonstrations, challenges remain with regards to improving growth rates to reduce cost of boules and understanding the growth behavior of GaN in these environments to further improve upon crystal quality. In particular, the general trend and affect of the GaN seed crystal on growth rates and crystal quality has not been studied in detail.This talk will discuss our current understanding of how the initial seed crystal orientation affects the resulting ammonothermal GaN growth, surface morphology, crystal quality, and impurity incorporation. Seed crystals were sourced from hydride vapor phase epitaxial (HVPE) grown GaN boules that were sliced and polished to atomically smooth crystallographic facets of varying orientations. Three series were created resulting in incrementally changing orientations ranging from +c-plane to m-plane to -c-plane, from +c-plane to a-plane to -c-plane and from m-plane to a-plane.

Stimuli-Responsive CeO2 Removal Via Surface Redox Modulation during Shallow Trench Isolation (STI) Post-Chemical Mechanical Planarization (p-CMP)

As transistor miniaturization continues to extend Moore’s Law into the future of technology, the demand for high-efficiency device manufacturing processes has increased drastically in recent years. More specifically, a critical step in preparing integrated circuits (ICs) and logic devices is Chemical Mechanical Planarization (CMP), which relies on a delicate balance of chemical and mechanical parameters to achieve angstrom-level surface uniformity and ultimately allows for increased transistor packing density. A sub-area of CMP that has gained significant attention is Shallow Trench Isolation (STI), which involves the isolation of electrically active components by removing the bulk oxide (i.e., tetraethyl orthosilicate (TEOS)) overburden from the deposition process. During polishing, chemical slurries comprised of CeO2 nanoparticles, rate enhancers, selectivity and rheology modifiers, and pH adjusters are utilized to activate the oxide layer and consequently remove material. The STI removal mechanism, known as the chemical tooth model, involves the nucleophilic attack of CeO2 nanoparticles at surface defect states (i.e., oxygen vacancies (Ovacs)) and resultant dative Ce-O-Si bond formation, which makes the surface redox state of CeO2 (i.e., Ce3+/Ce4+) a key driver for oxide-nanoparticle interactions. It is well known that Ce3+ nanoparticles contain a higher concentration of Ovacs, which enhances the material removal rate (MRR). However, the hard adsorption properties of CeO2 have resulted in the demand for a more efficient post-CMP (p-CMP) cleaning process for TEOS that promotes increased CeO2 removal without inducing secondary defects (i.e., scratching, dishing, corrosion, etc.). Current industry-standard methods involve using a polyvinyl alcohol (PVA) brush to transport harsh chemistries to contaminated surfaces under high shear force (SF). Additionally, the use of megasonic energy is an emerging non-contact cleaning mode that relies on generating reactive oxygen species (ROS) (i.e., cavitations) to induce particle removal. Previous work has shown that supramolecular additives improve overall particle removal efficiency (PRE) when implemented in traditional PVA brush cleaning due to their ability to encapsulate and charge-flip CeO2 nanoparticles while reducing SF. As a result, this research investigates a combinatorial approach to PVA brush cleaning utilizing megasonic energy to release Fenton catalysts from polymer capsules, which aid in the production of ROS through H2O2 decomposition. Initial results have shown that, by increasing the concentration of ROS during cleaning, a Ce3+ à Ce4+ transition occurs on the surface of adsorbed CeO2, enhancing overall PRE.

Constant Pressure-Regulated Microdroplet Polymerase Chain Reaction in Microfluid Chips: A Methodological Study.

Digital polymerase chain reaction (PCR) technology in microfluidic systems often results in bubble formation post-amplification, leading to microdroplet fragmentation and compromised detection accuracy. To solve this issue, this study introduces a method based on the constant pressure regulation of microdroplets during PCR within microfluidic chips. An ideal pressure reference value for continuous pressure control was produced by examining air solubility in water at various pressures and temperatures as well as modeling air saturation solubility against pressure for various temperature scenarios. Employing a high-efficiency constant pressure device facilitates precise modulation of the microfluidic chip's inlet and outlet pressure. This ensures that air solubility remains unsaturated during PCR amplification, preventing bubble precipitation and maintaining microdroplet integrity. The device and chip were subsequently utilized for quantitative analysis of the human epidermal growth factor receptor (EGFR) exon 18 gene, with results indicating a strong linear relationship between detection signal and DNA concentration within a range of 101-105 copies/μL (R2 = 0.999). By thwarting bubble generation during PCR process, the constant pressure methodology enhances microdroplet stability and PCR efficiency, underscoring its significant potential for nucleic acid quantification and trace detection.

Proof of Aerobically Autoxidized Self-Charge Concept Based on Single Catechol-Enriched Carbon Cathode Material

HighlightsAn air-breathing chemical self-charge concept of oxygen-enriched carbon cathode.The oxygen-enriched carbon material with abundant catechol groups.Rapid air-oxidation chemical self-charge of catechol groups.The self-charging concept has drawn considerable attention due to its excellent ability to achieve environmental energy harvesting, conversion and storage without an external power supply. However, most self-charging designs assembled by multiple energy harvesting, conversion and storage materials increase the energy transfer loss; the environmental energy supply is generally limited by climate and meteorological conditions, hindering the potential application of these self-powered devices to be available at all times. Based on aerobic autoxidation of catechol, which is similar to the electrochemical oxidation of the catechol groups on the carbon materials under an electrical charge, we proposed an air-breathing chemical self-charge concept based on the aerobic autoxidation of catechol groups on oxygen-enriched carbon materials to ortho-quinone groups. Energy harvesting, conversion and storage functions could be integrated on a single carbon material to avoid the energy transfer loss among the different materials. Moreover, the assembled Cu/oxygen-enriched carbon battery confirmed the feasibility of the air-oxidation self-charging/electrical discharging mechanism for potential applications. This air-breathing chemical self-charge concept could facilitate the exploration of high-efficiency sustainable air self-charging devices.

Enhanced electron–phonon coupling by delocalizing phonon states for desirable interlayer transfer of excited charges in MoSSe/WS2 heterobilayer

Regulating the interlayer transfer of excited charges is challenging but crucial for high-efficiency photoelectric conversion devices based on semiconductor heterojunction. In this work, the interlayer transfer and recombination of excited charges are investigated for the heterobilayers based on monolayer MoSSe and WS2 by combining density functional theory calculation with nonadiabatic molecular dynamics simulation. Our results reveal that the heterobilayers possess type-II band alignments and the interface engineering from S–Se to S–S stacking configuration reverses the spatial distribution of valence and conduction bands from MoSSe and WS2 to WS2 and MoSSe layers, respectively, which produces interlayer transfer of excited charges in opposite direction. The interface engineering also causes the delocalization of out-of-plane phonon states from the WS2 layer to both WS2 and MoSSe layers. This delocalized character in S–S configuration facilitates the simultaneous coupling of out-of-plane phonon states with the localized donor and acceptor electronic states, accelerates the motion of interface atoms, and reduces the band energy differences, which synergistically promote interlayer transfer of excited charges. As a result, the interlayer transfer of excited charges in S–S configuration is faster than that in S–Se configuration. Our investigation demonstrates that delocalizing phonon states through interface engineering can regulate electron–phonon coupling and interlayer transfer of excited charges.

Development of a High-Efficiency Device for Thermal Neutron Detection Using a Sandwich of Two High-Purity 10B Enriched Layers.

The shortage of 3He, a crucial element widely used as a neutron converter in neutron detection applications, has sparked significant research efforts aimed at finding alternative materials, developing appropriate deposition methods, and exploring new detector architectures. This issue has required the exploration of novel approaches to address the challenges faced in neutron detection. Among the available conversion materials, 10B has emerged as one of the most promising choices due to its high neutron-capture cross-section and relatively high Q value. In our previous papers, we delved into the possibility of depositing neutron conversion layers based on 10B using Pulsed Laser Deposition (PLD). We investigated and evaluated the performance of these layers based on various factors, including deposition conditions, substrate properties, and film thickness. Moreover, we successfully developed and tested a device that employed a single conversion layer coupled with a silicon particle detector. In this current study, we present the development of a new device that showcases improved performance in terms of efficiency, sensitivity, and discrimination against γ background signals. The background signals can arise from the environment or be associated with the neutron field. To achieve these advancements, we considered a new detection geometry that incorporates the simultaneous use of two 10B conversion layers, each with a thickness of 1.5 μm, along with two solid-state silicon detectors. The primary objective of this design was to enhance the overall detection efficiency when compared to the single-layer geometry. By employing this novel setup, our results demonstrate a significant enhancement in the device's performance when exposed to a neutron flux from an Am-Be neutron source, emitting a flux of approximately 2.2 × 106 neutrons per second. Furthermore, we established a noteworthy agreement between the experimental data obtained and the simulation results.

A Reconfigurable Three-Dimensional Electromagnetically Induced Transparency Metamaterial with Low Loss and Large Group Delay

In this paper, a solid-state plasma (SSP) metamaterial for an analog of the electromagnetically induced transparency phenomenon is designed and investigated. This electromagnetically induced transparency metamaterial has the ability to interact with both incident electric and magnetic fields, and its low-loss characteristics, slow-wave effect, band reconfigurability, and polarization-insensitive characteristics are researched and explored. According to the tunable SSP, we have successfully implemented two modes of operation (mode 1 and mode 2) by whether the SSP resonance unit is excited or not. Low-loss characteristics and polarization-insensitive properties are achieved by rotating the split-ring resonator (SRR) by 180° in the plane and rotating the overall plane framework 90° to form a three-dimensional structure. After that, the maximum group delay of 261.51 ps and 785.09 ps as well as the delay bandwidth product of 17.51 and 62.96 at mode 1 and mode 2, respectively, are discussed respectively. This indicates a good slow-wave effect as well as a high efficiency of communication devices. After all, in mode 1, a transmission peak at 0.541 THz is observed for a transmission ratio of 92.05%; and in mode 2, a transmission peak at 0.741 THz is observed for a transmission ratio of 93.01%, resulting in a bandwidth shift of 0.2 THz. Due to the uniqueness of the developed metamaterial, it holds potential for a wide range of applications in slow-wave devices, modulators, sensors, and communications equipment.

Novel cathode buffer layer enabling over 21.6%/20.9% efficiency in wide bandgap/inorganic perovskite solar cells

Different types of hybrid organic/inorganic halide perovskite solar cells (PSCs) have attracted extensive research attention and showed extremely considerable practical application potential in current energy field, for instance, wide bandgap (WBG) PSCs are widely used in fabricating high-efficiency tandem devices, while inorganic perovskite solar cells (IPSCs) had been sought after by researchers due to its excellent thermal stability. However, either WBG PSCs or IPSCs were severely influenced by the carrier extraction and transport between the electron transfer layer and anode/cathode. On this basis, an in-situ oxygen plasma treated Ti doped ZnO film named TZO (O) was used as cathode buffer layer to regulate the energy-level alignment between the SnO2 layer and ITO electrode, optimize the crystal quality of perovskite and passivate perovskite defects through providing superior SnO2 film. It is found that the more suitable energy levels for the interlamination availably polished up carrier transport effect to a great extent, which could be seen in steady-state and time-resolved photoluminescence spectra, in addition to this, the perovskite film covered on TZO (O)/ SnO2 demonstrated larger perovskite crystals and less surface defects. As a consequence, the power conversion efficiency (PCE) of the optimized device with a bandgap of ≈ 1.66 eV up to 21.62%, and the efficiency of CsPbI2.85Br0.15 IPSCs is enhanced from 19.21% to 20.92%. Moreover, the unencapsulated TZO (O)-treated wide bandgap PSCs shows enhanced stability, retaining 89.47% of its initial efficiency after 1000 h in a N2 filled environment, while the unencapsulated IPSCs-based TZO (O) still remains 83.77% of its initial efficiency under continuous illumination in air for 325 h. This work exhibited that the buffer layer TZO (O) is a promising interfacial modification material for both n-i-p type wide bandgap PSCs and IPSCs.

Ultra-low loss SOI waveguide crossings designed by a hybrid global optimization based on deep learning

We demonstrate an ultra-low loss single-mode silicon waveguide crossing and an ultra-compact and ultra-low loss polarization-insensitive silicon waveguide crossing using a hybrid global optimizer based on a physics-informed generative adversarial network with a direct binary search refinement. By adopting this method, a parallel waveguide crossing structure with a footprint of 3 × 4 μm2 for transverse electric(TE) mode which has an insertion loss better than 0.03 dB and has crosstalk lower than −27 dB in 1500∼1600 nm bands is designed. A polarization-insensitive waveguide crossing with the same footprint is also designed in 1530∼1570 nm bands, which can provide insertion loss lower than 0.2 dB and crosstalk lower than −26.3 dB for TE mode and insertion loss lower than 0.1 dB and crosstalk lower than −27.8 dB transverse magnetic(TM) mode. The results show that this global optimizer produced high-efficiency devices while avoiding being trapped in the local optimal solutions compared to the traditional stochastic inverse design algorithm.

Highly Efficient and Stable ITO-Free Organic Solar Cells Based on Squaraine N-Doped Quaternary Bulk Heterojunction.

Simultaneously achieving high efficiency and robust device stability remains a significant challenge for organic solar cells (OSCs). Solving this challenge is highly dependent on the film morphology of the bulk heterojunction (BHJ) photoactive blends; however, there is a lack of rational control strategy. Herein, it is shown that the molecular crystallinity and nanomorphology of nonfullerene-based BHJ can be effectively controlled by a squaraine-based doping strategy, leading to an increase in device efficiency from 17.26% to 18.5% when doping 2wt% squaraine into the PBDB-TF:BTP-eC9:PC71 BM ternary BHJ. The efficiency is further improved to 19.11% (certified 19.06%) using an indium-tin-oxide-free column-patterned microcavity (CPM) architecture. Combined with interfacial modification, CPM quaternary OSC excitingly shows an extrapolated lifetime of ≈23 years based on accelerated aging test, with the mechanism behind enhanced stability well studied. Furthermore, a flexible OSC module with a high and stable efficiency of 15.2% and an overall area of 5 cm2 is successfully fabricated, exhibiting a high average output power for wearable electronics. This work demonstrates that OSCs with new design of BHJ and device architecture are highly promising to be practical relevance with excellent performance and stability.

The Physics and Manipulation of Dean Vortices in Single- and Two-Phase Flow in Curved Microchannels: A Review.

Microchannels with curved geometries have been employed for many applications in microfluidic devices in the past decades. The Dean vortices generated in such geometries have been manipulated using different methods to enhance the performance of devices in applications such as mixing, droplet sorting, and particle/cell separation. Understanding the effect of the manipulation method on the Dean vortices in different geometries can provide crucial information to be employed in designing high-efficiency microfluidic devices. In this review, the physics of Dean vortices and the affecting parameters are summarized. Various Dean number calculation methods are collected and represented to minimize the misinterpretation of published information due to the lack of a unified defining formula for the Dean dimensionless number. Consequently, all Dean number values reported in the references are recalculated to the most common method to facilitate comprehension of the phenomena. Based on the converted information gathered from previous numerical and experimental studies, it is concluded that the length of the channel and the channel pathline, e.g., spiral, serpentine, or helix, also affect the flow state. This review also provides a detailed summery on the effect of other geometric parameters, such as cross-section shape, aspect ratio, and radius of curvature, on the Dean vortices' number and arrangement. Finally, considering the importance of droplet microfluidics, the effect of curved geometry on the shape, trajectory, and internal flow organization of the droplets passing through a curved channel has been reviewed.

The Transformative Power of Big Data: Leveraging Insights for Economic Growth, Environmental Preservation, and Societal Well-being

Due to the digitization revolution triggered by high-efficiency and low-price devices, the volume of data available worldwide has increased. Specialists have noted the flood of data called big data. Researchers and statisticians have begun to develop ways to use the big data obtained to improve human life, in the sense of considering its use. Indeed, the impact of big data has reached various areas. The data available from the databases have been analyzed and turned into information to obtain new concepts and ideas that benefit individuals and institutions in improving the economies of societies, achieving competitiveness, preserving the environment and health, protecting society and meeting needs, improving living standards, etc. As a result of the improvement in the use of big commercial and financial data, and the near future, and the improvement of commercial and financial policies to answer the study’s dilemma, documentary, and literary sources were used as tools for gathering information to analyze the subject. Keywords: Big data, sustainable development, trade decision-making, improved performance.

Optimization Mechanism of Nozzle Parameters and Characterization of Nanofibers in Centrifugal Spinning

Nanofibers are an emerging kind of nano-material, widely used in several application domains such as biomedicine, high-efficiency filtration media, precision electronics, and optical devices. Centrifugal spinning, which is a novel nanofiber production technology, has been widely studied. This paper proposes a structural parameter optimization design method of a bent-tube nozzle. The mathematical model of the spinning solution motion in the nozzle is first developed. The optimization function of the structure parameters of the bent-tube nozzle is then obtained by calculation. Afterwards, these parameters are optimized using a neural network algorithm. The obtained results show that, when the bending angle is 15°, the curvature radius is 10 mm, the outlet radius is 0.205 mm, and the head loss of the solution can be minimized. Finally, centrifugal spinning experiments are conducted and the influence of the centrifugal spinning parameters on the nanofibers is analyzed. In addition, the optimized bent-tube nozzle improves the surface morphology of the nanofibers as their diameter distribution becomes more uniform.

A numerical investigation of subcooled flow boiling heat transfer in twisted elliptical tubes

Twisted elliptical tubes possess superior heat transfer performance due to their unique geometry. It is necessary to further explore their potential applications in high-efficiency heat transfer devices. This study conducted a numerical simulation investigation to analyze the flow boiling heat transfer characteristics of subcooled water inside twisted elliptical tubes. The results show that the spiral flow inside twisted elliptical tube causes the fluid with relatively small vapor volume fraction to tend to distribute near the wall, while also increases turbulence intensity and promotes interactions among bubbles. Moreover, increasing the aspect ratio of the twisted elliptical tube can effectively improve the heat transfer coefficient and has a relatively small impact on the pressure drop of the fluid in the tube. Simulation data show that when the aspect ratio increases from 1.41 to 1.80, the heat transfer coefficient of the pipe increases by 15.21 %, while the pressure drop increases by 3.34 %.

MOCVD grown ultraviolet microlight-emitting diodes with an InGaN/GaN/AlGaN active region design

In this work, we present an InGaN/GaN/AlGaN active region design for high-efficiency UV LED grown by MOCVD. The use of the GaN layer allows the AlGaN layer to be grown in optimized conditions which will enhance the overall crystal quality and device performance. The InGaN/GaN/AlGaN structure showed an improvement in the internal quantum efficiency (IQE) simulation in comparison with the conventional InGaN/AlGaN structure, with 15% and 14% at operating current density of 20 and 30 A/cm2, respectively. The IQE advantage remains at more than 10% in the operating current density range from 0 to 100 A/cm2 due to an enhanced electron-hole wavefunction overlap. The InGaN/GaN/AlGaN quantum wells were utilized to grow UV-A structures and micro-LEDs with sizes ranging from 20 × 20 to 100 × 100 μm2 were fabricated. The fabricated micro-LEDs showed a reliable emission at around 372 nm with 9 nm FWHM. Micro-LED devices with smaller sizes showed an improvement in relative external quantum efficiency due to its advantage in current spreading. This manuscript presents the potential to achieve both improved crystal quality and high-efficiency device using InGaN/GaN/AlGaN active region design.

Cobalt-Free BaFe0.6Zr0.1Y0.3O3−δ Oxygen Electrode for Reversible Protonic Ceramic Electrochemical Cells

Reversible protonic ceramic electrochemical cells (R-PCECs) are ideal, high-efficiency devices that are environmentally friendly and have a modular design. This paper studies BaFe0.6Zr0.1Y0.3O3−δ (BFZY3) as a cobalt-free perovskite oxygen electrode for high-performance R-PCECs where Y ions doping can increase the concentration of oxygen vacancies with a remarkable increase in catalytic performance. The cell with configuration of Ni-BZCYYb/BZCYYb/BFZY3 demonstrated promising performance in dual modes of fuel cells (FCs) and electrolysis cells (ECs) at 650 °C with low polarization resistance of 0.13 Ω cm2, peak power density of 546.59 mW/cm2 in FC mode, and current density of − 1.03 A/cm2 at 1.3 V in EC mode. The alternative operation between FC and EC modes for up to eight cycles with a total of 80 h suggests that the cell with BFZY3 is exceptionally stable and reversible over the long term. The results indicated that BFZY3 has considerable potential as an air electrode material for R-PCECs, permitting efficient oxygen reduction and water splitting.

A comprehensive study of mechanically stacked tandem photovoltaic devices: Materials selection and efficiency analysis using SCAPS

To advance the photovoltaic industry, highly efficient solar modules with reduced manufacturing and installation costs are needed amidst rapid market growth. To surpass the performance limitations of single-junction solar cells, multijunction configurations have been the focus of rigorous study. The current work showcases a comprehensive investigation into the development and optimization of four terminal tandem solar cell architectures, with a focus on exploring the most technologically viable impactful, and promising combinations of top cell materials (CdTe, GaAs, MAPbI3, and MASnI3) and bottom cell options (c-Si and CIGS). Through numerical simulations using the Solar Cell Capacitance Simulator SCAPS and meticulous analysis, considering crucial parameters such as bandgap, charge carrier mobility, and defect densities, this study aims to identify the most promising material combinations for achieving high-efficiency tandem devices. The findings reveal that when c-Si is used as the bottom cell absorber, the tandem device as a whole produces a higher power conversion efficiency than when CIGS is used. The top cell options, namely CdTe, GaAs, MAPbI3, and MASnI3 in conjunction with c-Si as the bottom cell, achieve maximum efficiencies of 27.23%, 29.31%, 31.66%, and 15.64% respectively. In contrast, when paired with CIGS as the bottom cell, the efficiencies slightly decrease to 23.76%, 26.43%, 28.45%, and 12.83%. Notably, the investigation involving 25%, 50%, and 75% Br-doped MASnI3 alongside c-Si reveals efficiencies of 16.59%, 14.94%, and 14.28% respectively. In the case of CIGS, the corresponding efficiencies for 25%, 50%, and 75% Br doping are slightly lowered to 13.78%, 12.17%, and 11.43%. The obtained results offer valuable insights that can guide future research endeavors and foster the development of more efficient and commercially viable solar energy conversion technologies in the field of tandem photovoltaics.