Improved Power Conversion Efficiency Research Articles

Investigating Dopant Effects in ZnO as an Electron Transport Layer for Enhanced Efficiency in Organic Photovoltaics

AbstractThe power conversion efficiencies of organic solar cells greatly depend on the device architecture and choice of charge transporting materials. Improved power conversion efficiency (PCE) for inverted organic solar cells is observed when using Sn‐doped ZnO as the electron transporting layer. By doping the elements with different numbers of valence electrons (Al3+ and Sn4+ ions) into the ZnO matrix, device conversion efficiencies of 8.69% and 9.21%, respectively, are achieved. Conductive atomic force microscopy (CAFM) observations reveal that the Sn‐doped ZnO film exhibits better conductivity due to its larger number of carrier charges. X‐ray photoemission spectroscopy (XPS) indicates larger oxygen vacancies (OV) in Sn‐doped ZnO. Electrochemical characterization exhibits that there is a reduction in series resistance and charge transfer (CT) resistance for SZO, indicating the optimal charge transport capability of the electron transport layer (ETL). Ultrafast time‐resolved studies further show that, in comparison with Al‐doped ZnO and un‐doped ZnO, the elevated carrier concentration in Sn‐doped ZnO plays a significant role in augmenting the photocurrent. Thus, it is determined how dopants in ETL influence CT mechanisms, enhancing the photovoltaic conversion efficiency, thus contributing to the development of cost‐effective and efficient photovoltaic technologies.

MXenes in Perovskite Solar Cells: Emerging Applications and Performance Enhancements

Perovskite solar cells (PSCs) have emerged as promising candidates for next-generation photovoltaic technology due to their remarkable power-conversion efficiencies (PCEs). Since their introduction, the PCE of PSCs has advanced from 3.8% to over 26%. Nonetheless, challenges pertaining to stability and reliability continue to impede their commercial viability. Recent progress in interface engineering and materials science has underscored the potential of two-dimensional (2D) materials, particularly MXenes, in mitigating these challenges. MXenes represent a class of two-dimensional materials with significant potential for application in PSCs, attributed to their exceptional electrical conductivity, high carrier mobility, remarkable optical transparency, chemical stability, and tunable surface chemical properties. When employed as electron transport layers, MXenes enhance charge transfer and extraction efficiency, leading to substantial improvements in PCEs. Furthermore, their integration into hole transport layers and use as interfacial modifiers contribute to the mitigation of degradation pathways, thereby enhancing device longevity. The unique structural and electronic characteristics of MXenes facilitate their application as transparent electrodes, presenting opportunities for cost reduction and improved optical properties. This review provides a comprehensive overview of the current advancements in MXene-based PSCs, emphasizing significant accomplishments and exploring future research directions aimed at enhancing the efficiency and stability of these devices.

Highly accurate, efficient, and fabrication tolerance-aware nanostructure prediction for high-performance optoelectronic devices

Despite extensive efforts to predict optimal nanostructures for enhancing optical devices, a more accurate, efficient, and practical method for nanostructure optimisation is required. In particular, fabrication tolerance is a promising avenue for significantly improving manufacturing efficiency; however, research in this area is limited. In this study, we introduce a practical approach for enhancing the performance of optoelectronic devices using an artificial intelligence (AI)-based nanostructure optimisation strategy. We optimised a support vector regression (SVR) model to capture the complex and nonlinear relationships between the transmittance and nanograting structure variables with the goal of improving optoelectronic devices. Our versatile model accurately predicted the continuous transmittance data with high precision (R2 = 0.995) using only 216 training data points. It can also make predictions under untrained conditions, thereby enabling the creation of a transmittance nanostructure contour map (R2 = 0.949). This method facilitates the design of nanostructures tailored to specific optical properties and provides valuable insights into fabrication tolerance. Through experimental validation, we identified an optimal nanograting structure with the highest transmittance in the visible-light spectrum. When integrated into optoelectronic devices such as organic light-emitting diodes (OLEDs) and organic solar cells (OSCs), their performance is significantly improved by increasing the light transmittance. Specifically, devices using the fabricated nanograting film exhibited a 17% improvement in external quantum efficiency (EQE) for solution-processed organic light-emitting diodes (SP-OLEDs) and a 10.7% improvement in power-conversion efficiency (PCE) for OSCs.

Tuning of the Polymeric Nanofibril Geometry via Side-Chain Interaction toward 20.1% Efficiency of Organic Solar Cells.

Constructing fibril morphology has been believed to be an effective method of achieving efficient exciton dissociation and charge transport in organic solar cells (OSCs). Despite emerging endeavors on the fibrillization of organic semiconductors via chemical structural design or physical manipulation, tuning of the fibril geometry, i.e., width and length, for tailored optoelectronic properties remains to be studied in depth. In this work, a series of alkoxythiophene additives featuring varied alkyl side chains connected to thiophene are designed to modulate the growth of fibril aggregates in cutting-edge polymer donors PM6 and D18. Molecular dynamics simulations and morphological characterizations reveal that these additives preferentially locate near and entangle with the side chains of polymer donors, which enhance the conjugated backbone stacking of polymer donors to form nanofibrils with the width expanding from 12.6 to 21.8 nm and the length increasing from 98.3 to 232.7 nm. This nanofibril structure is feasible to acquire efficient exciton dissociation and charge transport simultaneously. By integrating the fibril PM6 and L8-BO as the donor and acceptor layers in pseudo-bulk heterojunction (p-BHJ) OSCs via layer-by-layer deposition, an improvement of power conversion efficiency (PCE) from 18.7% to 19.8% is observed, contributed by enhanced light absorption, charge transport, and reduced charge recombination. The versatility of these additives is also verified in D18:L8-BO OSCs, with enhanced PCE from 19.3% to 20.1%, which is among the highest values reported for OSCs.

Construction of ultra-smooth and void-free buried interface via bilateral chemical bridging for efficient and hysteresis-suppressed perovskite solar cells

The surface properties are vital aspects in improving photovoltaic performance of perovskite solar cells (PSCs). Except for the upper surface of perovskite, the hidden buried interface which supports the beginning of perovskite film crystallization is of equal great importance for the construction of high-efficiency PSCs. Herein, we use urea phosphate (UPP) to build a bilateral chemical bridge in the buried interface under perovskite layer, to simultaneously improve the properties of SnO2 ETL and the upper perovskite. On one hand, the interaction between UPP and SnO2 passivates the defects of the SnO2 and facilitates the formation of ultra-smooth surface for superior interfacial contact. On the other hand, the chemical interaction between UPP and perovskite contributes to the optimization of crystal nucleation and growth, which improves the crystalline quality of perovskite, inhibits the formation of voids at the buried interface and reduces the defects of the grain boundary. Benefiting from the optimized buried interfacial contact, suppressed defects, accelerated charge extraction and modified energy level alignment, the UPP-processed device delivers an improved power conversion efficiency of 24.54 %, with effective suppression of hysteresis. Moreover, the stability of device is also improved owing to the reduction of trap defects. This work provides a feasible strategy to tune the buried interface between the charge transfer layer and perovskite layer for fabrication of efficient and stable PSCs.

U-Shaped Dimeric Acceptors for Balancing Efficiency and Stability in Organic Solar Cells.

Despite significant improvements in power conversion efficiencies (PCEs) of organic solar cells (OSCs), achieving excellent stability remains a great challenge to their commercial feasibility. Here, U-shaped dimeric acceptors (5-IDT and 6-IDT) with different molecular lengths are introduced into the binary OSCs as a third component, respectively. The introduction of the third component effectively reduces the energetic disorder and non-radiative voltage losses and improves the exciton dissociation and charge transport of the devices. Consequently, the PCEs of the 6-IDT- and 5-IDT-treated OSCs are significantly improved to 19.32% and 19.96%, respectively, which is the highest PCE for oligomeric acceptors-based ternary OSCs to date. Meanwhile, the thermal stability of the treated devices is dramatically improved, with the initial efficiency retention of the 6-IDT- and 5-IDT-treated devices increasing from 18% to 32% and 75%, respectively, after 1000h of thermal stress. This is mainly attributed to the ability of the smaller molecular length of 5-IDT to stabilize the phase-separated morphology of the polymeric donor and small molecular acceptor, rather than the high glass transition temperature and low diffusion coefficient.

Minimizing interfacial energy losses via fluorination strategy toward high-performance air-fabricated perovskite solar cells

Sub-bandgap state-induced radiative recombination and trap-assisted nonradiative recombination at the interface between the perovskite layer and hole transport layer in n-i-p perovskite solar cells (PSCs) significantly limit further improvements in power conversion efficiency (PCE) and stability. In this work, we introduce a simple yet effective fluorination strategy to mitigate these recombination losses by simultaneously achieving defect passivation, tensile strain release, and modulation of interfacial energy band alignment. The incorporation of fluorine (F) groups not only enhances defect passivation through strong chemical bonding but also improves the moisture resistance of perovskite films and devices. We reveal the critical influence of the number and position of F groups on the benzene ring in determining device photovoltaic performance. PSCs modified with 3,5-difluoro-benzamidine hydrochloride (3,5-DFBH) demonstrate a remarkable PCE of 24.57 %, coupled with enhanced long-term stability. These PSCs, among the highest-performing devices fabricated in ambient air, maintained over 90 % of their initial power conversion efficiency (PCE) after 2700 h of storage at 10 % to 20 % relative humidity, and withstood 1700 h of exposure to heat at 65 °C. This work provides a viable pathway to simultaneously improve both the photovoltaic performance and stability of PSCs by mitigating sub-bandgap and trap-assisted recombination through fluorination.

Photonic crystal surface emitting lasers with multiple-junction operating at high order waveguide mode

We propose a novel design for multi-junction photonic crystal surface emitting lasers (PCSELs) operating in higher-order waveguide modes to minimize internal losses. This paper details the design and simulation of a 2-junction PCSEL, including calculations of confinement factors, coupling coefficients, radiation loss, and threshold currents. We compare the performance of 2 J-PCSELs and 1 J-PCSELs, demonstrating the potential for highly efficient multi-junction PCSELs with improved power conversion efficiency and output power.

Eco-friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles for enhanced dye-sensitized solar cells utilizing oxalis Corniculata leaf extract

An environmentally friendly synthesis of Nd³⁺-doped Eu₂O₃ nanoparticles (NPs) was developed using Oxalis Corniculata leaf (OCL) extract to enhance the performance of dye-sensitized solar cells (DSSCs). The as-synthesized NPs were annealed at 600 °C to improve their crystallinity. X-ray diffraction and field-emission scanning electron microscopy revealed high crystallinity and a sub-100 nm spherical morphology. Annealing reduced the NP size from ∼85 nm to ∼45 nm and decreased the bandgap from 4.97 eV to 4.62 eV, enhancing low-energy photon absorption. Fourier-transform infrared spectroscopy showed changes in the chemical bonding environment, with a higher presence of dangling bonds in the as-prepared NPs compared to the 600 °C-annealed NPs, likely due to the OCL extract. Photoluminescence spectra confirmed strong red emission peaks at 580 nm and 612 nm, with a slight reduction in the full width at half maximum of the electric dipole transition after annealing. Integrating these NPs into TiO₂ matrices in DSSCs improved power conversion efficiency to 8.58%, outperforming both as-prepared NPs (6.88%) and bare TiO₂ cells (5.05%). This green synthesis approach offers a sustainable pathway for slightly enhancing performance of photovoltaic devices, with additional potential for UV-shielding applications when incorporated into PVA films.

High-performance CIGS solar cells using a double active layers approach – SCAPS 1D optoelectronic modeling approach

One of the properties of the CIGS solar cell is that it can have an adjustable band gap energy. The band gap varies in the range from 1.01 to 1.7 eV as a function of materials content. Enhancing the bandgap profile of the active layer, which is where the majority of charge carrier photo-generation occurs, should significantly improve cell performance. Superimposing absorber layers with different electrical characteristics is one way of refining the bandgap profile and achieving these results. It is possible to analyze the optoelectronic output properties and simulate this active multilayer approach using a reference cell thanks to the SCAPS numerical modeling tool. Considering this, we have successfully simulated the following structure: CIGS2/CIGS1/SDL/ZnS/ZnO. The SDL which stands for Surface Defect Layer, has been considered for the property discontinuity interface, mainly characterized by the formation of defect states. That enabled to achieve realistic-like device with an improvement of power conversion efficiency (PCE) up to 11.98 %, i.e. 29.22 % and a fill factor (FF) of 82 % employing a total thickness of active layer of 800 nm. All simulations were performed considering experimental environment parameters, an external temperature of 300 K, light illumination of AM1.5G and defects states were assumed in both the bulk and at interfaces.

Enhancing photovoltaic cell design with multilayer sequential neural networks: A study on neodymium-doped ZnO nanoparticles

Multilayer sequential neural networks, a powerful machine learning model, demonstrate the ability to learn intricate relationships between input features and desired outputs. This study focuses on employing such models to design photovoltaic cells. Specifically, neodymium (Nd)-doped ZnO nanoparticles (NPs) were utilized as a photoanode for fabricating dye-sensitized solar cells (DSSCs). A natural dye extracted from Spinacia oleracea was employed, while two types of electrolytes, liquid and gel (polyethylene glycol-based), were used for comparative analysis. Extensive material characterization of the photoanode highlights the impact of Nd content on the physicochemical properties of ZnO. Notably, when the doped photoanode and gel electrolyte were combined, a substantial 110% improvement in power conversion efficiency (PCE) was achieved. Building on these findings, the machine learning model in this research accurately predicts the current-voltage (I-V) curve values for such photoanodes, with an impressive accuracy of 98%. Additionally, the model illuminates the significance of variables like crystal distortion, texture coefficient, and doping concentration, underscoring their importance in the context of photovoltaic cell design.

Advancements and Challenges in Antenna Design and Rectifying Circuits for Radio Frequency Energy Harvesting.

The proliferation of smart devices increases the demand for energy-efficient, battery-free technologies essential for sustaining IoT devices in Industry 4.0 and 5G networks, which require zero maintenance and sustainable operation. Integrating radio frequency (RF) energy harvesting with IoT and 5G technologies enables real-time data acquisition, reduces maintenance costs, and enhances productivity, supporting a carbon-free future. This survey reviews the challenges and advancements in RF energy harvesting, focusing on far-field wireless power transfer and powering low-energy devices. It examines miniaturization, circular polarization, fabrication challenges, and efficiency using the metamaterial-inspired antenna, concentrating on improving diode nonlinearity design. This study analyzes key components such as rectifiers, impedance matching networks, and antennas, and evaluates their applications in biomedical and IoT devices. The review concludes with future directions to increase bandwidth, improve power conversion efficiency, and optimize RF energy harvesting system designs.

Enhanced Performance of Close-Spaced Sublimation Processed Antimony Sulfide Solar Cells via Seed-Mediated Growth.

Antimony sulfide (Sb2S3) has attracted much attention due to its great prospect to construct highly efficient, cost-effective, and environment-friendly solar cells. The scalable close-spaced sublimation (CSS) is a well-developed physical deposition method to fabricate thin films for photovoltaics. However, the CSS-processed absorber films typically involve small grain size with high-density grain boundaries (GBs), resulting in severe defects-induced charge-carrier nonradiative recombination and further large open-circuit voltage (VOC) losses. In this work, it is demonstrated that a chemical bath deposited-Sb2S3 seed layer can serve as crystal nuclei and mediate the growth of large-grained, highly compact CSS-processed Sb2S3 films. This seed-mediated Sb2S3 film affords reduced defect density and enhanced charge-carrier transport, which yields an improved power conversion efficiency (PCE) of 4.78% for planar Sb2S3 solar cells. Moreover, the VOC of 0.755V that is obtained is the highest reported thus far for vacuum-based evaporation and sublimation processed Sb2S3 devices. This work demonstrates an effective strategy to deposit high-quality low-defect-density Sb2S3 films via vacuum-based physical methods for optoelectronic applications.

Researching Organic Solar Cells from the Perspective of Literature Big Data Analysis

Solar cell research aims to improve power conversion efficiency (PCE). This field has an extensive body of literature on the Web of Science. For researchers, it is impossible to understand the development of the entire field comprehensively through traditional reading methods. Knowledge is recorded in the literature by text and numbers. Researchers acquire knowledge through literature surveying, text reading, and thinking. The conversion from text and numbers to knowledge can be automatically completed by machines, which can avoid path‐dependent perspectives. In this work, an intelligent machine learning method for literature structure delineation and information extraction is proposed. As an example, a knowledge base of organic solar cells (OSCs) is extracted including topic analysis of literature, numerical characteristics of performance, and material information. Seven major research directions of OSCs are identified. The correlations between key performance parameters, including PCE, short‐circuit current density (JSC), open‐circuit voltage (VOC), and fill factor (FF), are revealed from text mining. A donor–acceptor material map of PCE is constructed which provides a road map for OSCs, indicating the bottleneck of this field. Moreover, the method of machine intelligence developed here can be used in any other materials field, aiding a comprehensive understanding of the development quickly.

Numerical optimization of inorganic p-Sb2Se3/n-ZrS2 heterojunction solar cells: achieving high efficiency through SCAPS-1D simulation

p-Sb2Se3 and n-ZrS2 materials show strong potential for cost-effective photovoltaic applications. This study presents a detailed numerical analysis of p-Sb2Se3/n-ZrS2 heterojunction solar cells using SCAPS-1D, focusing on how key parameters such as layer thickness, doping density, and bandgap have affected device performance. Critical photovoltaic metrics, such as built-in voltage (Vbi), carrier lifetime, depletion width (Wd), recombination rates, and photogenerated current, were examined. Our findings demonstrate that optimizing the p-Sb2Se3 absorber layer with a 1.0 eV bandgap, 5000 nm thickness, and doping density of 1020 cm−3 leads to a maximum efficiency of 32.14%, with a fill factor (FF) of 84.57%, short-circuit current density (Jsc) of 47.61 mA cm−2, and open-circuit voltage (Voc) of 0.792 V. For the ZrS2 buffer layer, the best performance was achieved with a 1.2 eV bandgap, 200 nm thickness, and doping density below 1 × 1020 cm−3. These optimized parameters significantly enhanced carrier separation and minimized recombination losses, leading to improved power conversion efficiency. In addition to theoretical optimization, this study emphasizes the practical potential of these materials for real-world applications. The combination of Sb2Se3 and ZrS2 offers a low-cost fabrication process suitable for scalable commercial solar cell production while maintaining high efficiency. These results underscore the viability of p-Sb2Se3/n-ZrS2 heterojunctions as promising candidates for next-generation clean energy solutions.

Design and Simulation for Minimizing Non-Radiative Recombination Losses in CsGeI2Br Perovskite Solar Cells.

CsGeI2Br-based perovskites, with their favorable band gap and high absorption coefficient, are promising candidates for the development of efficient lead-free perovskite solar cells (PSCs). However, bulk and interfacial carrier non-radiative recombination losses hinder the further improvement of power conversion efficiency and stability in PSCs. To overcome this challenge, the photovoltaic potential of the device is unlocked by optimizing the optical and electronic parameters through rigorous numerical simulation, which include tuning perovskite thickness, bulk defect density, and series and shunt resistance. Additionally, to make the simulation data as realistic as possible, recombination processes, such as Auger recombination, must be considered. In this simulation, when the Auger capture coefficient is increased to 10-29 cm6 s-1, the efficiency drops from 31.62% (without taking Auger recombination into account) to 29.10%. Since Auger recombination is unavoidable in experiments, carrier losses due to Auger recombination should be included in the analysis of the efficiency limit to avoid significantly overestimating the simulated device performance. Therefore, this paper provides valuable insights for designing realistic and efficient lead-free PSCs.

Room-Temperature Ripening Enabled by Hygroscopic Salts for Hole-conductor-Free Printable Perovskite Solar Cells with Efficiency Over 20 .

Solution-processed perovskite films generally possess small grain sizes and high density of grain boundaries, which intensify non-radiative recombination of carriers and limit the power conversion efficiency (PCE) of solar cells. In this study, we report the room-temperature ripening enabled by the synergy of hygroscopic salts and moisture in air for efficient hole-conductor-free printable mesoscopic perovskite solar cells (p-MPSCs). Treating perovskite films with proper hygroscopic salts in damp air induces obvious secondary recrystallization, which coarsens the grains size from hundreds of nanometers to several micrometers. It's proposed that the hygroscopic salt at grain boundaries could absorb moisture and form a complex which could not only serve as mass transfer channel but also assist in the dissolution of perovskite grains. This activates mass transfer between small grains and large grains since they possess different solubilities, and thus ripens the perovskite film. Consequently, p-MPSCs treated with the hygroscopic salt of NH4SCN show an improved power conversion efficiency of 20.13 % from 17.94 %, and maintain >98 % of the initial efficiency under maximum power point tracking at 55±5 °C for 350 hours.

Sputter-deposited TiOx thin film as a buried interface modification layer for efficient and stable perovskite solar cells

Despite perovskite solar cells (PSCs) based on a SnO2 hole-blocking layer (HBL) are achieving excellent performance, the non-perfect buried interface between the SnO2 HBL and the perovskite layer is still an obstacle in achieving further improvement in power conversion efficiency (PCE) and stability. The poor morphology with numerous defects and the energy level mismatch at the buried interface constrain the open circuit voltage and cause instability. Herein, a sputter-deposited TiOx thin film is used as a buried interface modification layer to address the aforementioned issues. Utilizing in situ grazing-incidence small-angle X-ray scattering (GISAXS) during the sputter deposition, we monitor and unveil the growth process of the TiOx thin film, identifying a 10 nm thickness optimum. The defects at the buried interface are passivated through tuning the growth, leading to a suppressed non-radiative recombination and improved PCE (from 22.19 % to 23.93 %). The evolution of the device performance and the degradation process of PSCs using operando grazing-incidence wide-angle X-ray scattering (GIWAXS) under the protocol ISOS-L-1I explains the enhanced stability introduced by the buried interface modification via a sputter-deposited TiOx thin layer. The perovskite decomposition process and the detrimental formation of PbI2 are both slowed down by the TiOx thin layer.

Organic Salt Buffer Layer Enables High‐Performance NiOx‐Based Inverted Perovskite Solar Cells

The merits of a low‐cost fabrication process, suitable band structure, excellent wettability to perovskite precursor, and outstanding stability ensure NiOx as a hole transport material with beneficial characteristics to construct high‐performance perovskite solar cells (PSCs). However, direct contact between perovskite and NiOx causes delamination and chemical instability and thus results in poor carrier transport and short device lifespan. Here, we propose a solution for this issue by introducing an organic salt additive 4‐(trifluoromethyl) benzylammonium formate (TFMBAFa) in the perovskite precursor to passivate perovskite film and NiOx@(2‐(3,6‐dimethyl‐9H‐carbazol‐9‐yl) ethyl) phosphonic acid (Me‐2PACz) composited hole transport layer (HTL), and thus construct a buffer layer between perovskite‐HTL interface. The effective diminishing of NiOx/perovskite interfacial reactions and defects results in enhanced carrier transport. Consequently, the target device achieves simultaneous improvements in power conversion efficiency (24.2%), storage stability (T100 > 1400 h), thermal stability (T80 > 1000 h), and operational stability (T70 > 850 h), where T100, T80, and T70 refer to the retention of 100%, 80%, and 70% of initial PCE, respectively. This work provides an effective strategy to advance the performance of NiOx‐based inverted PSCs.

Loading Precursors into Self‐Assembling Contacts for Improved Performance and Process Control in Evaporated Perovskite Solar Cells

Organo‐lead‐halide perovskites are promising materials for solar cell applications with efficiencies now exceeding 26% for single junction, and over 33% for silicon tandem devices. Evaporation has proven viable for industrial scale‐up but presents challenges for perovskite materials. Perovskite precursor is introduced into self‐assembling MeO‐2PACz hole transport layers for application to 4 source perovskite coevaporation. This allows precursors that can be difficult to add via evaporation, like methylammonium chloride. These precursor molecules influence growth during evaporation, film behavior during annealing as measured by photoluminescence, and aid the conversion to perovskite as shown by X‐Ray diffraction. Devices have improved power conversion efficiency and stability compared to a control sample within the same evaporation. The best cells reach ≈21% efficiency and comparable performing ≈20% cells maintain their original efficiency after 1000 h of maximum power tracking at 25 °C. This process provides significant process flexibility for perovskite evaporation and requires no additional steps.