Efficiency Enhancement Of Solar Cells Research Articles

Photovoltaic Efficiency Enhancement of Indium-Free Wide-Bandgap Chalcopyrite Solar Cells via an Aluminum-Induced Back-Surface Field Effect.

Wide-bandgap chalcopyrite materials are attractive candidates for a wide variety of energy conversion devices such as the top cell of tandem-type photovoltaic devices and photoelectrochemical water splitting hydrogen evolution devices. Nevertheless, simultaneous realization of high open circuit voltage (VOC) and high fill factor (FF) values has been challenging, and thus, the photovoltaic performance has been limited. In this article, high VOC and high FF values of wide-gap chalcopyrite CuGaSe2 thin-film solar cells are simultaneously demonstrated using an aluminum-induced back-surface field effect. An independently certified photovoltaic efficiency of 12.25% was obtained from an elemental In-free CuGaSe2:Al (bandgap energy ∼1.7 eV) solar cell (VOC: 0.959 V, short circuit current density: 17.64 mA cm-2, FF: 72.5%). In addition, an over 1 V-VOC CuGaSe2 cell (FF: 74.5%) was obtained even with the use of a conventional CdS buffer layer. Although incorporation of aluminum often leads to degradation of the chalcopyrite solar cell performance, the addition of a small amount of aluminum is found to be effective in enhancing wide-gap chalcopyrite photovoltaic performance.

SCAPS numerical modeling of CBTS/WO3 thin film solar cell

The quaternary compound Cu2BaSnS4 (CBTS) has emerged as a suitable and attractive light-harvesting material due to its promising optoelectronic features as well as nontoxic and low-cost constituent elements. Yet efficiency of CBTS-based solar cells did not reach the Shockley-Queisser limit. Here, what we believe to be a novel structure ITO/WO3/CBTS heterojunction solar cell is designed and modeled using a solar cell capacitance simulator in one-dimension (SCAPS-1D). In this work, a what we also believe to be a novel WO3 as a buffer layer is proposed for the first time for the efficiency enhancement of CBTS thin film solar cells. Numerical investigation of the performance of CBTS-based solar cells without and with cuprous oxide (Cu2O) back surface field (BSF) is explored. The impact of thickness, doping density, bulk, and interface defect density of an absorber, buffer and window layer, working temperature, shunt and series resistance, back contact work function, and back surface recombination velocity were analyzed and optimized without and with the BSF layer. In this work, the optimized solar cell achieved an efficiency of 18.8%, fill factor (FF) of 83.79%, short-circuit current density (JSC) of 15.99 mA/cm2, and open circuit voltage (VOC) of 1.4 V without Cu2O BSF layer at optimal CBTS absorber and WO3 buffer layer thickness of 2 µm and 0.04 µm respectively. Furthermore, the efficiency boosted to 21.12% with VOC of 1.43 V, JSC of 16.8 mA/cm2 and FF of 87.77% by inserting 0.1 µm Cu2O BSF layer. Therefore, these results will facilitate the fabrication of an efficient and low-cost CBTS-based solar cell with promising WO3 and Cu2O as buffer and BSF layer, respectively.

Performance improvement tactics of sensitized solar cells based on CuInS2 quantum dots prepared by high temperature hot injection

To reveal the ways and causes of conversion efficiency enhancement for quantum dot-sensitized solar cells (QDSSCs), chalcopyrite structure CuInS2 quantum dots (QDs) was synthesized in oil phase by the high temperature hot injection method. Then, QDs were transferred from oil phase to water phase with 3-mercaptopropionic acid as a ligand exchange reagent and loaded inducer of QDs. 3-mercaptopropionic acid coated QDs in water phase were sensitized on TiO2 nanocrystalline thin films to fabricate QDSSCs. The sensitization time of QDs and pH value in QDs solution are two important factors to affect the loading amounts of QDs and performance of the final assembled QDSSCs. Long-time sensitization of QDs on the TiO2 porous thin film will cause QDs to agglomerate and stack on the film. The pH of QDs aqueous solution influences the stable existence in solution of QDs and adsorption on the surface of TiO2. By balancing the influence of the above two factors, the optimal sensitization condition of CuInS2 QDs is adsorption in pH = 11 QDs solution for 2 h. In addition, the interface between QD-sensitized TiO2 porous thin film and FTO is another factor to affect the photoelectric conversion efficiency of QDSSCs. By adding Zn-doped TiO2 compact layer with high conductivity and electron mobility on QDSSCs to modify this interface, the photoelectric conversion efficiency of QDSSCs was further increased by 66.4 %.

SiNPs Decoration of Silicon Solar Cells and Size Analysis on the Downshifting Mechanism Response for the Enhancement of Solar Cells Efficiency

SiNPs Decoration of Silicon Solar Cells and Size Analysis on the Downshifting Mechanism Response for the Enhancement of Solar Cells Efficiency

Exploring the efficiency enhancement of perovskite solar cells by chemical bath depositing SnO2 on mesoporous TiO2 electrode

This study presents a groundbreaking approach to enhance the efficiency of perovskite solar cells (PSCs) by employing Chemical Bath Deposited (CBD) SnO2 on mesoporous TiO2 (m-TiO2) as an electron transport layer (ETL) without a traditional compact TiO2 (c-TiO2) layer between FTO (fluorine-doped tin oxide) and m-TiO2 ETL. Our investigation reveals that this method significantly improves carrier dynamics, as evidenced by reduced time constants compared to traditional ETLs. The CBD SnO2 not only augments electron transport but also effectively reduces defect density in m-TiO2 films. These enhancements are reflected in the improved photovoltaic parameters of the cells, including higher open-circuit voltage (VOC), short-circuit current (JSC), fill factor (FF), and an impressive power conversion efficiency (PCE) exceeding 23.62 %. The study further underscores the scalability of this technology, highlighting advancements in screen printing and chemical bath deposition techniques vital for large-area PSC applications. Remarkably, the uniformity of PCE across large-area cells confirms the efficacy and consistency of this approach, which provides a new and general strategy for preparing high-efficiency PSCs.

Design of experiments with the support of machine learning for process parameter optimization of all‐small‐molecule organic solar cells

AbstractTraditionally, squaraine dyes have been studied and employed in biomedical research due to their excellent optical properties, and the molecules are being adopted in different research fields such as organic solar cells. In this study, we investigate correlations between solar cell performance and processing parameters of all‐small‐molecule bulk heterojunction solar cells comprising squaraine (SQ) as electron donor (D) and non‐fullerene small molecules (e.g., ITIC) as electron acceptor (A) with the help of machine learning (ML) and design of experiment (DoE) methods. Among the five predictive ML models tested with the selected parameters, the eXtreme gradient boosting model shows the satisfactory results with quite high coefficient of determination of 0.999 and 0.997 in training and testing sets, respectively. By measuring the contribution of each input variable to solar cell efficiency, four process parameters, that is, the total concentration, the ratio of D/A, the rotational speed of spin coating, and the annealing temperature, are found to be the key features strongly correlated to solar cell efficiency. From contour plots in DoE, the highest solar cell efficiency of approximately 5% can be predicted under the conditions of 15 mg mL−1 in solution concentration, a 1:2 mix ratio of D and A, rotational speeds ranging from 800 to 900 rpm, and annealing temperatures within 100–110°C. Using the suggested parameter conditions, we fabricated solar cells, achieving a quite high efficiency of approximately 4%. Besides the global optimization conditions, we also employ the solvent vapor annealing combination to the thermal annealing to facilitate further mobilization of molecules and more optimized microstructure of bulk heterojunction films, resulting in a further enhancement in solar cell efficiency of more than 20%.

Efficiency enhancement and optimization of lead-free Cs2PtI6 perovskite solar cell

Perovskite solar cells (PSCs) are famous for their potential to produce efficient, flexible, and low-cost solar energy. This study explores the possibility of eco-friendly, lead-free, inorganic solar cells using Cs2PtI6 as the light-absorbing layer and NiO as the hole transport layer (HTL). It carefully optimizes various factors, including the thickness, doping concentration, defect density, and the effects of radiative recombination of the absorber layer, along with different hole and electron transport layers. The study also examines interfacial defects and resistances within the device. The density of defects at the interface between the HTL and the absorber layer is a crucial factor influencing the device’s performance. Additionally, the study evaluates different metal back contacts, changes in temperature, light intensity, and the spectrum of light. The optimized structure (FTO/ZnO/Cs2PtI6/NiO/Au) achieves an open circuit voltage (VOC) of 1.34 V, a short-circuit current (JSC) of 32.34 mAcm−2, a fill factor (FF) of 75.70%, and an excellent power conversion efficiency (PCE) of 32.70%, showing great promise in solar cell technology.

Efficiency Enhancement of Lead-Free CsSnGeI3-Based Perovskite Solar Cells Using ZnSe as an Electron Transport Material and Spiro-MeOTAD as the Hole Transport Material

Efficiency Enhancement of Lead-Free CsSnGeI3-Based Perovskite Solar Cells Using ZnSe as an Electron Transport Material and Spiro-MeOTAD as the Hole Transport Material

Unraveling Interfacial Photoinduced Charge Transfer and Localization in CsPbBr3 Nanocrystals/Naphthalenediimide.

Halide perovskites have attracted much attention for energy conversion. However, efficient charge carrier generation, separation, and mobility remain the most important issues limiting the higher efficiency of solar cells. An efficient interfacial charge transfer process associated with exciton dynamics between all-inorganic CsPbBr3 nanocrystals and organic electron acceptors has been suggested. We observed a strong PL quenching of 78% in thin films when silane-functionalized naphthalenediimides (SNDI), used as electron-acceptors, are anchored on CsPbBr3 nanocrystals. Optical and structural characterizations confirm the charge transfer process without QDs degradation. The issue of whether these transferred charges are indeed available for utilization in solar cells remains uncertain. Our results reveal that the CsPbBr3 nanocrystals capped with these electron-acceptor SNDI molecules show a drastic increase in the electrical resistance and the absence of a photoconductivity effect. The results suggest charge transfer followed by strong localization of the charge carriers, preventing their extraction toward the electrodes of solar cell devices. We hope that this crucial aspect to attract attention and unveil a potential mechanism for charge delocalization, which could, in turn, lead to a groundbreaking enhancement in solar cell efficiency.

Efficiency enhancement of ultrathin CIGS solar cells by optimal bandgap grading. Part III: piecewise-homogeneous grading

In Parts I [ Appl. Opt. 58, 6067 (2019)APOPAI0003-693510.1364/AO.58.006067] and II [ Appl. Opt. 61, 10049 (2022)APOPAI0003-693510.1364/AO.474920], we used a coupled optoelectronic model to optimize a thin-film CIGS solar cell with a graded-bandgap photon-absorbing layer, periodically corrugated backreflector, and multilayered antireflection coatings. Bandgap grading of the CIGS photon-absorbing layer was continuous and either linear or nonlinear, in the thickness direction. Periodic corrugation and multilayered antireflection coatings were found to engender slight improvements in the efficiency. In contrast, bandgap grading of the CIGS photon-absorbing layer leads to significant enhancement of efficiency, especially when the grading is continuous and nonlinear. However, practical implementation of continuous nonlinear grading is challenging compared to piecewise-homogeneous grading. Hence, for this study, we investigated piecewise-homogeneous approximations of the optimal linear and nonlinear grading profiles, and found that an equivalent efficiency is achieved using piecewise-homogeneous grading. An efficiency of 30.15% is predicted with a three-layered piecewise-homogeneous CIGS photon-absorbing layer. The results will help experimentalists to implement optimal designs for highly efficient CIGS thin-film solar cells.

Perovskite half tandem v-shaped grating nanostructure solar cells: Improvement by light trapping and carrier transfer towards efficiency enhancement

In this paper, the enhancement of the perovskite solar cells (PSCs) efficiency through the implementation of a half-tandem structure featuring two absorbent layers of MAPbI3 and MoTe2 with a V-shaped nanostructured grating was investigated. MoTe2 was utilized as the second lower absorbent with a smaller bandgap than the first and upper absorbent, MAPbI3, to cover the incident light absorption in the infrared wavelength range. Additionally, the structure was also optimized by introducing a nanostructured V-shaped grating to increase the light propagation path and improve the absorption in the active layers. Also, the critical role of the electron transfer layer (ETL) and hole transfer layer (HTL) in carrier transfer and prevention of charge leakage was examined for materials including TiO2, TiO2-Gr (5%) nanocomposite, and Al-doped ZnO (AZO) as ETLs, and Cu2FeSnS4 (CFTS) and reduced Graphene Oxide (rGO) as HTLs in four distinct cell configurations. In this study, the optical and electrical models were solved to determine the optimal solar cell structure and materials through a comparative analysis of structures. Our findings revealed substantial improvements in short-circuit current density (Jsc), open-circuit voltage (Voc), and power conversion efficiency (PCE), where they increased from 15.27 to 31.55 mA/cm2, 0.91 to 1.30 V, and 11.78 to 27.63%, respectively. This resulted in a 2.35 times efficiency enhancement for the nanostructured V-shaped half-tandem solar cell with MAPbI3 (250 nm) and MoTe2 (150 nm) as absorbent layers, AZO (40 nm) as ETL and rGo (40 nm) as HTL compared to the planar non-tandem solar cell with MAPbI3 (250 nm) as absorbent layer, TiO2 (40 nm) as ETL and CFTS (40 nm) as HTL.

Efficiency and stability enhancement in FA-based perovskite solar cells using controlled reduction of graphene oxide interlayer – An experimental investigation

Reduced graphene oxide (rGO) as an interlayer and interface engineer, due to its conductivity and hydrophobicity, can be coated on top of perovskite layers to increase the photovoltaic performance and stability of perovskite solar cells. Herein, we employed reduced graphene oxide as an interlayer. By controlling the reduction level of rGO, its potential for boosting perovskite solar cells' efficiency was further increased. Results showed that increasing the reduction degree of rGO to an optimal level increased its conductivity and hole mobility, which induced charge transfer at perovskite/hole transport layer and increased the open-circuit voltage of solar cells. Our rGO reduction controlling strategy enables FAPbI3-based solar cells to record a PCE of 22.29%. In addition, increasing reduction degree increased hydrophobicity behavior of rGO. It increased perovskite solar cell resistance against humidity and heating degradation. The developed method in current study can push up perovskite solar cells to industrialization.

Influence of Eu3+ ion concentration on La2Al0.5Li0.5O4 phosphor for LEDs and solar cell efficiency enhancement

Eu-doped La2Al0.5Li0.5O4 samples were prepared using simple combustion method using urea-glycine as fuel, 800 °C of calcination follows. The samples are single phase and have crystallized into a tetragonal crystal structure with space group I4/mmm, according to Rietveld refinement analysis of XRD data. The transition peaks 5D0→7F0 and 5D0→7F2 found for peak at 593 nm and 614 nm in PL spectra. However PL emission intensity gets decreased on enhancing concentration of Eu3+ ion caused by concentration quenching phenomenon. Their intensity increases dramatically as a result of an efficient energy transfer from the oxygen vacancy state. The present sample can be used in UV-filter, UV-detector, optical devices, and WLEDs application applications by using these absorption states and emission states as metastable states. The initial efficiency of the silicon solar cell, on which this phosphor is coated, results in a 16.02% increase in intensity. This outcome shows that this phosphor is further useful in solar cell efficiency enhancement.

3% absolute efficiency gain on multicrystalline silicon solar cells by TiO2 antireflection coatings derived by APCVD process

This paper reports about the adaptation of the CVD thin films technology to the fabrication process of multicrystalline silicon (mc-Si) solar cells which is the key issue of modern method of photovoltaic power generation. In this contribution, the higher reflection of a mc-Si solar cell surface is strongly reduced by the deposition of TiO2 antireflection coating (ARC) on the front using CVD method at atmospheric pressure (APCVD). The surface morphology and elemental composition of the TiO2 antireflective layers were revealed using Scanning Electron Microscopy (SEM) in conjunction with Energy Dispersive X-ray Spectroscopy (EDS). The reflectivity was then reduced from 35% to 8.6% leading to the increase of the short circuit current Jsc which was about 33.86 mA/cm² with a benefit of 5.23 mA/cm² (surface area = 25 cm²) compared to reference cell (without ARC). This simple and low cost technology induces a 14.26% conversion efficiency which is a gain of + 3% absolute in comparison to reference cell. These results are encouraging and prove the effectiveness of the APCVD method for efficiency enhancement in silicon solar cells.

Improving Solar Cell Efficiency through Controlled Annealing Effects of TiO2 Thin Films

In the scope of this research, the impact of thermal annealing on the electrical and optical characteristics of TiO2 thin films is investigated through empirical analysis. Varied annealing temperatures are applied during the production of TiO2 thin films, and their reflection, transmission, absorption, and crystalline structure attributes are meticulously gauged. Through systematic analysis, the optimal annealing temperature is determined to be 500 °C. Remarkably, TiO2 thin films fabricated under this specific temperature exhibit notably reduced reflection values. Moreover, comprehensive scrutiny extends to encompass both electrical and structural attributes, such as carrier density, resistivity, and crystal size, in addition to optical attributes. In the outcome, it is revealed that TiO2 thin films subjected to annealing at 500 °C exhibit the highest carrier density and the lowest resistivity. X‐ray diffraction analyses unveil the anatase phase of TiO2 thin films developed at this temperature. Notably, ascending annealing temperatures correlate with amplified crystal sizes and increased surface roughness. Furthermore, the TiO2 thin films are subsequently integrated into crystalline silicon solar cells via employment of the SCAPS (a Solar Cell Capacitance Simulator) software, culminating in a noteworthy 8% enhancement in solar cell efficiency.

Modeling for Efficiency Enhancement of Perovskite Thin-Film Solar Cell by Using Double-Absorber and Buffer Layers

Perovskite solar cells appear to be the most promising candidate for thin-film solar cells. In this work, double layer Perovskite solar cells were simulated using a SCAPS-1D simulator in which different thickness of the perovskite layers was used, a buffer layer of PEDOT:PSS was used, the effect of defect density in absorbing layers, the influence of doping in Spiro-OMeTAD as well as the effect of temperature is studied. With this proposed simulated model, the maximum efficiency of the perovskite solar cell reaches 28.22%. Hence this simulation work will provide handy information in fabricating perovskite solar cells to reasonably choose material parameters and to achieve high efficiency.

Gold nanostructures/quantum dots for the enhanced efficiency of organic solar cells.

Incorporating gold nanoparticles (AuNPs) into organic solar cell (OSC) structures provides an effective means to manipulate light-matter interactions. AuNPs have been used as plasmonic-enhancement and light-trapping materials in OSCs and exhibit diverse single and mixed morphologies. Substantial near-field enhancement from metal periodic structures has consistently demonstrated high enhancement in solar cell efficiency. Additionally, coupling with atomic gold clusters in the form of gold quantum dots holds promise for light harvesting through fluorescence phenomena. The configured devices optimize light utilization in OSCs by considering factors such as the morphology, position, and hybridization of localized surface plasmon resonance, propagating surface plasmon resonance, and fluorescence phenomena. This optimization enhances light absorption, scattering, and efficient trapping facilitated by gold nanostructures/quantum dots. The configured setup exhibits multiple effects, concurrently improving plasmonic and fluorescence responses under solar irradiation, thereby enhancing energy conversion performance. Integrating plasmonic nanostructures with OSCs can address fundamental issues, providing opportunities to enhance the light-absorption intensity and charge transfer efficiency at intra and intermolecular levels. This comprehensive review demonstrates that the greatest improvement in solar cell efficiency exceeded 30% compared with the reference cells.

Bandgap reduction and efficiency enhancement in Cs2AgBiBr6 double perovskite solar cells through gallium substitution.

Lead-free halide double perovskite (LFHDP) Cs2AgBiBr6 has emerged as a promising alternative to traditional lead-based perovskites (LBPs), offering notable advantages in terms of chemical stability and non-toxicity. However, the efficiency of Cs2AgBiBr6 solar cells faces challenges due to their wide bandgap (Eg). As a viable strategy to settle this problem, we consider optimization of the optical and photovoltaic properties of Cs2AgBiBr6 by Gallium (Ga) substitution. The synthesized Cs2Ag0.95Ga0.05BiBr6 is rigorously characterized by means of X-ray diffraction (XRD), UV-vis spectroscopy, and solar simulator measurements. XRD analysis reveals shifts in peak positions, indicating changes in the crystal lattice due to Ga substitution. The optical analysis demonstrates a reduction in the Eg, leading to improvement of the light absorption within the visible spectrum. Importantly, the Cs2Ag0.95Ga0.05BiBr6 solar cell exhibits enhanced performance, as evidenced by higher values of open circuit voltage (Voc), short-circuit current (Jsc), and fill factor (FF), which are 0.94 V, 6.01 mA cm-2, and 0.80, respectively: this results in an increased power conversion efficiency (PCE) from 3.51% to 4.52%. This research not only helps to overcome film formation challenges, but also enables stable Cs2Ag0.95Ga0.05BiBr6 to be established as a high-performance material for photovoltaic applications. Overall, our development contributes to the advancement of environmentally friendly solar technologies.

Effective UV-protection and photovoltaic efficiency enhancement of polymer solar cells using diatom shells doped with Eu3+/Tb3+complexes

In this work, Eu3+/Tb3+complexes were anchored into diatom shells and mixed with cellulose acetate, and the resulting films with excellent UV-absorption were applied to polymer solar cells, improving the cell efficiency and lifetime.

Efficiency-enhancement of lead-free ASnI2Br perovskite solar cells by phenyltrihydrosilane passivation effective for Sn4+ reduction and hydrophobization

The efficiency enhancement of the tin perovskite solar cell consisting of ASnI2Br (ASnI2Br-PVK-PV) is discussed. The ASnI2Br-PVK-PV has a bandgap wider than 1.6 eV and is applicable to the top layer of Pb free perovskite/Si tandem solar cells. The low efficiency of the ASnI2Br-PVK-PV is due to the presence of Sn4+ and defects at the hetero interfaces. We found that PhSiH3 solution treatment (passivation) of the film surface decreases the Sn4+ concentrated on the surface of the perovskite film. At the same time, PhSiH3 treatment (passivation) made the surface of the perovskite layer hydrophobic, resulting in giving better contacts between the perovskite layer and the hydrophobic C60 layer. The efficiency was enhanced from 3.65% to 5.50% after the passivation, proving the effectiveness of the PhSiH3 treatment. The mechanism of the passivation is discussed.