Conversion Efficiency Of Devices Research Articles

Comprehensive Design and Analysis of Thin Film Sb2S3/CIGS Tandem Solar Cell: TCAD Simulation Approach

Abstract This research presents a design and analysis of a tandem solar cell, combining thin film wide bandgap Sb2S3 (1.72 eV) and narrow bandgap CIGS (1.15 eV) for the top and bottom sub-cells, respectively. The integration of all thin film layers enhances flexibility, rendering the tandem solar cell suitable for applications such as wearable electronics. To optimize the power conversion efficiency (PCE) of the tandem solar device, advanced technology computer-aided design (TCAD) simulation tools are employed to estimate loss mechanisms and fine-tune parameters for each layer. An experimentally validated optoelectronic model is introduced, calibrated and validated against fabricated reference solar cells for the individual top and bottom cells. The calibrated model is then utilized to propose optimization routines for the Sb2S3/CIGS tandem solar cell. The initial tandem cell exhibits a JSC of 15.72 mA/cm2 and a PCE of 15.36%. The efficiency drop in the tandem configuration is identified primarily in the top cell. A systematic optimization process for the top cell is initiated, exploring various configurations, including HTL-free and ETL-free setups. Moreover, an np homojunction structure for the top cell is proposed. Optimization routines are applied that involve determining optimal thickness and doping concentration of the n-layer, investigating the effect of p-layer doping concentration, and exploring the influence of the work function of the front contact. As a result, the tandem cell efficiency is significantly improved to 23.33% at the current matching point (CMP), with a JSC of 17.15 mA/cm2. The findings contribute to the advancement of thin-film tandem solar cell technology, showcasing its potential for efficient and flexible photovoltaic applications.

Implementation of a Multi-Functional-Group Strategy for Enhanced Performance of Perovskite Solar Cells through the Incorporation of 3-Amino-4-Phenylbutyric Acid Hydrochloride.

Reducing the defect density of perovskite films during the crystallization process is critical in preparing high-performance perovskite solar cells (PSCs). Here, a multi-functional molecule, 3-phenyl-4-aminobutyric acid hydrochloride (APH), with three functional groups including a benzene ring, ─NH3 + and ─COOH, is added into the perovskite precursor solution to improve perovskite crystallization and device performance. The benzene ring increases the hydrophobicity of perovskites, while ─NH3 + and ─COOH passivate defects related to I- and Pb2+, respectively. Consequently, the power conversion efficiency (PCE) of the optimal device increased to 24.65%. Additionally, an effective area of 1 cm2 with a PCE of 22.45% is also prepared using APH as an additive. Furthermore, PSCs prepared with APH exhibit excellent stability by 87% initial PCE without encapsulation after exposure at room temperature under 25% humidity for 5000 h and retaining 70% of initial PCE after aging at 85°C in an N2 environment for 864 h.

Hydrovoltaic Materials and Devices: From Synthetic Materials, Macroscopic Biomaterials, to Micro Biomaterials

Much progress has been made in hydrovoltaic materials and devices. However, the power conversion efficiency of hydrovoltaic devices is still low. One of the main factors that determine the efficiency is the properties of hydrovoltaic materials. Herein, the research status of hydrovoltaic materials is summarized from the perspectives of synthetic materials, macroscopic biomaterials, and micro biomaterials, as well as the hydrovoltaic devices based on these materials.

In-situ reaction modification of isocyanate derivatives with hole-transport units on perovskite film surface for efficient and stable solar cells

FAPbI3 perovskite solar cells (PSCs) have attracted widespread research attention. The interfacial properties play a crucial role in perovskite defect passivation and interfacial carrier transport, significantly influencing the power conversion efficiency (PCE) and stability of devices. Here, a novel interface modification strategy of in-situ reaction on perovskite surface is proposed. A molecule N,N′-bis(4-isocyanatophenyl)-N,N′-di-p-tolyl-[1,1′-biphenyl]-4,4′-diamine (TPD-NCO), involving a hole-transporting unit TPD was synthesized. The highly reactive isocyanate (NCO) groups addition-reacted with formamidine ions (FA+) from the FAPbI3 surface, forming urea with firm covalent bonds. The resulting stable modification smoothened the interface, and its urea groups coordinated with Pb2+ and formed hydrogen bonds with I-, thereby passivating the surface defects and inhibiting ion migration. Moreover, the hole-transporting units were firstly anchored through this covalent modification as a p-type dopant to lower the interface energy barrier for hole extraction. The PCE of target devices increased from 22.82% to 24.46%, which also remained 93% for 5460 h under high humidity (65% RH), 87% for 1060 h under 75 °C, and 77% for 420 h under maximum power point (MPP) operation at 50 °C, indicating both excellent efficiency and long-term stabilities. This work displays the value of both firm and hole-conductive features in in-situ reactive interface modification.

Highly Doped Conjugated Polyelectrolytes with Large Work Function for Efficient Hole Injection/Collection in Organic Photoelectric Devices

The existing deficiencies in traditional hole‐transporting layer (HTL) materials poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and molybdenum oxide restrict the further advance in the photoelectric conversion efficiency of organic photoelectric devices. Although conjugated polyelectrolytes (CPEs) display great advantage in serving as HTLs, the low work function (WF) and poor conductivity lead to the inferior performances of CPE‐modified devices. Herein, the important influence of electrostatic potential on p‐doping property of CPEs is revealed, and hence a series of CPEs with obvious p‐type self‐doping property based on simple chemical structures of benzene and thiophene derivatives are designed and synthesized. With a higher electron density of conjugated backbone, the CPE PB3T shows an improved doping effect. Moreover, a simultaneous enhancement of WF and conductivity can be achieved by doping the CPE with polyoxometalate (POM). The resulting CPE composite PB3T:POM exhibits good hole injection/collection ability and is compatible with large‐area production technique. The organic solar cells with active areas of 0.04 and 1.00 cm2 exhibit power conversion efficiency values of 18.1% and 15.6%, respectively. PB3T:POM is also used as HTL to fabricate organic light‐emitting diode (OLED) device, and the OLED exhibits a superior luminous efficiency to the PEDOT:PSS device but with a significantly reduced turn‐on voltage from 4.2 to 3.4 V.

A new alcohol-soluble dye-tetraphenyl porphyrin functionalized copolymer: Inside the role as a third component/cathode interlayer in halogen-free OSCs

Development and step-by-step characterizations of a novel cationic thiophene based copolymer (P1buP), including ionic phosphonium salt and dye-tetraphenylporphyrin (TPP) moiety in side chains, with an iconic property of solubility in a wide range of polar solvents is reported. Synthesized by using simple, low-cost, and straightforward procedures, the material is used to fabricate completely halogen-free (i.e., from ethanol) ternary organic solar cells (OSCs), in the presence of an alcohol-soluble ionic 3,4-dialkoxythiophene based homopolymer (P2buP) and a serinol-fullerene derivative (C60-Ser). Indeed, thanks to co-sensitization techniques, where multiple dyes harvest different parts of the solar spectrum, the power conversion efficiency of the best final device dramatically increases up to nearly 5.0%, as the light absorption is usually optimized. Additionally, since the use of a cathode interlayer in OSCs also plays a pivotal role in electron extraction and device stability, a possible application of the ionic TPP material as the interfacial layer is also investigated. Furthermore, to improve and optimize the best performing device, a successful post-metalation with Zn of the porphyrin core is carried out, and a ternary OSC (P1buP:P2buP:C60-Ser = 0.33:0.67:1 w/w) is fabricated, resulting in a photoconversion efficiency (PCE) of ~6.0%.

Effects of neodymium or ytterbium addition to CH3NH3PbI3 perovskite solar cells inserted with decaphenylcyclopentasilane

Perovskite solar cells have attained high photoconversion efficiencies by changing chemical compositions of the perovskites and layered structures of the devices. However, the perovskite compounds easily decompose in air atmosphere even at the room temperature, and the photovoltaic properties are degraded by the formed defects. The motivation of this work is to solve these instability problems, and the objective the present work is to improve the film quality of the perovskite compounds by introducing lanthanide elements and decaphenylcyclopentasilane (DPPS), which were expected to contribute to decrease of the defects by the passivation effects. Here, effects of neodymium trifluoride (NdF3) or ytterbium trifluoride (YbF3) addition to CH3NH3PbI3 perovskite solar cells inserted with DPPS were investigated. Introduction of NdF3 or YbF3 increased the lattice constants and promoted crystal growth of the perovskites, and surface treatment by DPPS suppressed the PbI2 formation as surface passivation. Combined additions of NdF3 or YbF3 and DPPS contributed to the improvement of both the conversion efficiencies of the present perovskite devices and the stabilities of the photovoltaic properties by inhibiting the decomposition.

Synchronous effect of coordination and hydrogen bonds boosting the photovoltaic performance of perovskite solar cells

Superior quality of perovskite film with perfect crystalline and low defect density is crucial for achieving excellent photovoltaic performance and durability of perovskite solar cells (PSCs), and regulation of growth of perovskite crystal and defects passivation by additive is remain challenge. Herein, two acyl molecules (Succinimide: SCI, and Hydantoin: HDT) were incorporated into perovskite precursor solution as additive. It can be found that the HDT molecule can not only passivate undercoordinated Pb2+ defects in perovskite films by the -C=O groups with coordination bonds, but also formed hydrogen bonds with I− by -NH- group, which effectively inhibited the formation of iodine vacancy defects and regulated growth rate of perovskite crystals, and the quality of perovskite films was optimized with enlarging grain size and reduced trap-density. Consequently, power conversion efficiency of HDT-based device was enhanced from 19.47 % to 21.00 %, with an enhancement of JSC and VOC. Moreover, the HDT-based device without encapsulation retained 83.7 % of its initial PCE after being aged at 10–20 % RH for 60 days. Obviously, such a study could provide a new strategy to optimize quality of perovskite film for boosting performance of PSCs.

Tailoring atomically local electric field of NiFe layered double hydroxides with Ag dopants to boost oxygen evolution kinetics

The demand for clean energy sources has driven focus towards advanced electrochemical systems. However, the sluggish kinetics of the oxygen evolution reaction (OER) constrain the energy conversion efficiency of relevant devices. Herein, a one-step method is reported to grow oxygen vacancies (Vo) rich NiFeAg layered double hydroxides nanoclusters on carbon cloth (Vo-NiFeAg-LDH/CC) for serving as the self-supporting electrode to catalyze OER. The OER performance of Vo-NiFeAg-LDH/CC has been remarkably enhanced through Ag and Vo co-modification compared with pristine NiFe-LDH, achieving a low Tafel slope of 49.7 mV dec−1 in 1 m KOH solution. Additionally, the current density of Vo-NiFeAg-LDH/CC is 3.23 times higher than that of the state-of-art IrO2 at 2 V under an alkaline flow electrolyzer setup. Theoretical calculations and experimental results collectively demonstrate that Ag dopant and Vo strengthen the O* adsorption with active sites, further promoting the deprotonation step from OH* to O* and accelerating the catalytic reaction. In a word, this work clarifies the structural correlation and synergistic mechanism of Ag dopant and Vo, providing valuable insights for the rational design of catalyst for renewable energy applications.

Structurally Flexible 2D Spacer for Suppressing the Electron–Phonon Coupling Induced Non-Radiative Decay in Perovskite Solar Cells

HighlightsThe soft 2D material reduces the coupling strength between carriers and longitudinal optical phonons, releasing the mechanical stress of lattice vibration.The power conversion efficiency of rigid devices and flexible devices reaches 25.5% and 23.4%, respectively.

Utilizing Metal Oxide Thin Films for Device Engineering of Solution-Processed Organic Multi-Junction Solar Cells

Electron and hole transporting layers play a major role in high-performance and stable organic-based optoelectronic devices. This paper demonstrates detailed device engineering of multi-junction organic photovoltaics built on two different metal oxide-based electron and hole transport (buffer) layers prepared by thermal or solution-processed methods. The main focus is on the device processing parameters as well as practical details of preparation of buffer layers to give the research community a clear, step-by-step recipe to successfully replicate and build series and parallel connected multi-junction solution-based organic solar cells for their needs. Here, the recipes and deposition conditions of two metal oxide buffer layers are presented in detail, based on basic commercially available materials and tools, to achieve well-engineered tandem (multi-junction) solution-processed organic solar cells. The buffer layers have appropriate energy levels for electrical selectivity of anode and cathode electrodes, and they are highly stable and chemically compatible with processing of solution-based polymer solar cells. To demonstrate the engineering steps of multi-junction devices, the PCE10:PC70BM blend is used as the active layer for all subcells. Then, to improve the power conversion efficiency of the single-junction photovoltaic device, PCE10:PC70BM blend is used in combination with DPPx:PC70BM with different absorption spectra for bottom and top subcell active layers. An optimized series tandem device with 10.6% power conversion efficiency is demonstrated. Generally, the device structures reported here can also be used for other types of optoelectronic devices, such as light emitting diodes and photodetectors.

Realization of high cryogenic thermoelectric performance for MgAgSb base alloy by regulation heat-treatment process

MgAgSb alloy has attracted wide attention due to its inherent low thermal conductivity, excellent thermoelectric (TE) properties, and environmental friendliness. Although the TE performance has been deeply investigated for the temperature range over 300–700 K, while cryogenic range has seldom report. In this study, a systematic investigation on cryogenic TE performance of α-MgAgSb has been performed. α-MgAgSb alloy has been synthesized by ordinary ball milling followed spark plasma sintering process and then further regulated by heat treatment. The power factor of MgAgSb alloy after 10 days of heat-treating increased by 230%, which is attributed to the reduction of the impurity phase and the improvement of the crystallinity achieved by the optimization of heat treatment. The total thermal conductivity decreased by 18% to 1.15 W m−1 K−1, and the maximum ZT reached 0.264 at 173 K, which is 300% enhancement to untreated one. The ZTavg reached to 0.45 over 173–298 K, located at the pinnacle among cryogenic TE materials. In addition, the ZTeng value of 0.23 related to the highest device conversion efficiency of 5.2% demonstrates good device potential. This work reveals that the purity and the cryogenic TE properties of α-MgAgSb alloy can be effectively improved by heat-treating, and demonstrates the greatly potential of MgAgSb materials in the field of liquefied natural gas's cold energy recovery.

A benzobisoxazole-based polymer assisting high efficiency polymer solar cells

Ternary strategy is an effective method to optimize photovoltaic process and improve device performance. In this work, a benzobisoxazole-based conjugated polymer PBBO was designed and employed as the guest component for PM6:BTP-eC9 based devices. The polymer PBBO shows a large band gap of 2.16 eV and strong photoluminescence property, with efficient energy transfer observed between PBBO and PM6. The ternary blends not only form a cascaded energy level distribution, but also an alloy-like structure, which can effectively promote the exciton dissociation, charge transfer and efficiently suppress charge recombination. As a result, the power conversion efficiency (PCE) of the ternary device is substantially improved from 17.50% to 18.66% with the incorporation of PBBO guest component. Meanwhile, the ternary device shows good stability with retaining 86% of initial efficiency after storage for 2000 hours. This research demonstrates that the polymer PBBO would be an excellent photovoltaic material to optimize the performance of polymer solar cells.

Analytical description of the charge-to-photon conversion efficiency for electroluminescent devices based on thermally activated delayed fluorescence

Analytical description of the charge-to-photon conversion efficiency for electroluminescent devices based on thermally activated delayed fluorescence

Improving photovoltaic characteristics of CdS-based hybrid solar cells through Mn incorporation

CdS thin films, both with and without Mn-doping, were grown via chemical bath deposition on indium tin oxide-coated glass substrates for application in hybrid solar cells. X-ray diffraction analysis revealed that Mn doping led to a deterioration in the crystal quality of CdS samples, evidenced by increased microstrain and dislocation density. Mn atoms were interstitially incorporated into the CdS structure, resulting in an expansion of the unit cell volume. Morphological analysis indicated a decrease in grain size from 390 nm to 140 nm for 0 % and 2 % Mn-doped CdS samples, respectively, while maintaining the spherical shape of the CdS thin films. Mn doping also increased the transmittance of CdS thin films, with the highest transparency of 95 % at 580 nm achieved for the 2 % Mn-doped CdS sample. In comparison to undoped CdS (2.38 eV), the band gap of CdS samples initially decreased to 1.84 eV for 1 % Mn doping but significantly increased to 3.03 eV for 2 % Mn-doped CdS. Photoluminescence (PL) data indicated that 2 % Mn-doped CdS thin films exhibited the lowest peak intensity, suggesting that a high concentration of Mn atoms caused non-radiative charge recombination. Additionally, efficient exciton dissociation was observed between CdS:Mn and P3HT:PCBM (poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM)) layers in the 2 % Mn-doped CdS-based device, as per the PL results. Photovoltaic measurements demonstrated that compared to undoped CdS, 2 % Mn doping increased the power conversion efficiency of the CdS-based device from 0.070 % to 0.202 %, indicating an almost threefold increase in hybrid solar cell efficiency. This improvement is likely attributed to the development of a better interface between the CdS:Mn and P3HT:PCBM layers.

Calculation on maximum output power of wave energy-PTO system

The energy conversion efficiency of wave energy device is one of the key problems in the large-scale utilization of wave energy. The study of the maximum output POWER of PTO (Power-Take-Off) system provides a theoretical reference for the efficient utilization of energy. In this paper, genetic algorithm and adaptive differential evolution algorithm based on neighborhood search are used to optimize the two-objective multi-order differential equations for the maximum output power of PTO system, and the global optimal solution is obtained. Compared with the traversal algorithm, the algorithm involved in this paper is efficient and the optimal output power obtained can provide a scientific basis for the structural optimization design and material selection of the wave energy device.

Impact of oxygen incorporation on interface optimization and defect suppression for efficiency enhancement in Cu2ZnSn(S,Se)4 solar cells

Kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells suffer from severe carrier recombination, limiting the photovoltaic performance. Unfavorable energy band alignment at the p-n junction and defective front interface are two main causes. Herein, oxygen incorporation in CZTSSe via absorber air-annealing was developed as a strategy to optimize its surface photoelectric property and reduce the defects. With optimized oxygen incorporation conditions, the carrier separation and collection behavior at the front interface of the device is improved. In particular, it is found that oxygen incorporated absorber exhibits increased band bending, larger depletion region width, and suppressed absorber defects. These indicate the dynamic factors for carrier separation become stronger. Meanwhile, the increased potential difference between grain boundaries and intra grains combined with the decreased concentration of interface deep level defect in the absorber provide a better path for carrier transport. As a consequence, the champion efficiency of CZTSSe solar cells has been improved from 9.74% to 12.04% with significantly improved open-circuit voltage after optimized air-annealing condition. This work provides a new insight for interface engineering to improve the photoelectric conversion efficiency of CZTSSe devices.

Research on Wave Energy Converters

With the acceleration of the global warming process, the clean energy crisis is becoming serious; conventional energy is unlikely to solve the current crisis, so people pay attention to new energy. As wave energy is widely distributed, renewable, and clean, hundreds of wave energy converters emerge. In order to understand the research progress of wave energy converters better, this paper divides wave energy converters into overtopping type, oscillating water column type, and oscillating body type according to the working principle and divides the oscillating body type into oscillating float type and oscillating pendulum type by different ways of energy capture. Based on the classification, various types of engineering cases, physical tests and digital simulation, and other academic research results are summarized, especially the generation power and energy conversion efficiency of various devices, and some shortcomings and suggestions are put forward, hoping to provide help for readers to study wave energy generation converters.

Study of Laser-Induced Multi-Exciton Generation and Dynamics by Multi-Photon Absorption in CdSe Quantum Dots.

Multi-exciton generation by multi-photon absorption under low-energy photons can be thought a reasonable method to reduce the risk of optical damage, especially in photoelectric quantum dot (QD) devices. The lifetime of the multi-exciton state plays a key role in the utilization of photon-induced carriers, which depends on the dynamics of the exciton generation process in materials. In this paper, the exciton generation dynamics of the photon absorption under low-frequency light in CdSe QDs are successfully detected and studied by the temporal resolution transient absorption (TA) spectroscopy method. Since the cooling time of hot excitons extends while the rate of auger recombination is accelerated when incident energy is increased, the filling time of defect states is irregular, and exciton generation experiences a transition from single-photon absorption to multi-photon absorption. This result shows how to change the excitation. Optical parameters can prolong the lifetime of excitons, thus fully extracting excitons and improving the photoelectric conversion efficiency of QD optoelectronic devices, which provides theoretical and experimental support for the development of QD optoelectronic devices.

Transferred Metal Electrodes for Perovskite Solar Cells with Doping‐Tuned Hole‐Transporting Layer

As an alternative technology to the standard evaporated metal top electrode in perovskite solar cells, the transfer method top electrode is featured with low cost, simple process, and ease of scalability. However, as the transfer method preparation of the less expensive metal electrodes (Ag and Cu) is explored, the mismatch between the hole‐transport layer and the top electrode results in anomalous photovoltaic properties. In this study, the work function of the hole‐transporting material is adjusted by changing the dopant content to achieve a good energy‐level match with either Ag or Cu electrode material. The power conversion efficiencies of perovskite devices based on transferred Ag and Cu electrodes can reach 18.41% and 17.25%, respectively, which are comparable to the performance of the evaporated top electrode devices.