High-efficiency Solar Cell Devices Research Articles

Dynamic Reconstruction of Fluid Interface Manipulated by Fluid Balancing Agent for Scalable Efficient Perovskite Solar Cells.

Laboratory-scale spin-coating techniques are widely employed for fabricating small-size, high-efficiency perovskite solar cells. However, achieving large-area, high-uniformity perovskite films and thus high-efficiency solar cell devices remain challenging due to the complex fluid dynamics and drying behaviors of perovskite precursor solutions during large-area fabrication processes. In this work, a high-quality, pinhole-free, large-area FAPbI3 perovskite film is successfully obtained via scalable blade-coating technology, assisted by a novel bidirectional Marangoni convection strategy. By incorporating methanol (MeOH) as a fluid balance agent, the direction of Marangoni convection is effectively regulated, mitigating the disordered motion of colloidal precursor particles during the printing process. As a result, champion power conversion efficiencies (PCEs) of 24.45% and 20.32% are achieved for small-area FAPbI3 devices (0.07cm2) and large-area modules (21cm2), respectively. Notably, under steady illumination, the device reached a stabilized PCE of 24.28%. Furthermore, the unencapsulated device exhibited remarkable operational stability, retaining 92.03% of its initial PCE after 1800h under ambient conditions (35±5% relative humidity, 30°C). To demonstrate the universality of this strategy, a blue perovskite light-emitting diode is fabricated, showing an external quantum efficiency (EQE) of 14.78% and an electroluminescence wavelength (EL) of 494nm. This work provides a significant technique for advancing solution-processed, industrial-scale production of high-quality and stable perovskite films and solar cells.

Enhanced charge separation at the interface of Cu2O/CuSCN composite thin films synthesized by electrodeposition technique

This study focuses on the synthesis and characterization of hole transport layers (HTLs) for solar cells, par- ticularly copper(I) thiocyanate (CuSCN) and cuprous oxide (Cu2O), synthesized via electrodeposition tech- niques. CuSCN and Cu2O offer promising properties for efficient charge transport in photovoltaic devices. The synthesis processes involve precise control of deposition parameters to achieve desired film morpholo- gies and properties. Characterization techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), and ultraviolet-visible (UV-Vis) spectroscopy provide insights into film morphology and optical properties. Optimization of synthesis parameters for Cu2O films is explored to enhance their electrical properties. Photoelectric response measurements indicate improved charge separation at the interface of Cu2O/CuSCN composite films. These findings can contribute to the advancement of solar cell technology. Furthermore, the study extends its exploration to the fabrication of Cu2O by electrodeposition at different pH levels. SEM and X-ray diffraction (XRD) analyses reveal the impact of deposition parameters on film mor- phology and crystal structure, providing valuable insights for tailored synthesis approaches. Overall, this comprehensive study not only advances the understanding of HTL materials synthesis and optimization but also provides valuable guidance for the development of high-efficiency and stable solar cell devices.

Tuning of Optoelectronic Characteristics of Quinoxalineimide-based Novel Non-Fullerene Acceptors for Organic Photovoltaic Applications

Organic solar cells (OSCs) have made remarkable progress due to developing novel materials and device architectures. Herein, we designed six new non-fullerene acceptors (QM1–QM6) having a quinoxalineimide (QI) as the central-building-block. We aimed to explore the potential of QI-containing structures for developing high-performance acceptors for OSCs. These designed molecules possess a fusion of the QI unit with a thienylthiophene backbone and are equipped with various efficient end-capping groups. Extensive theoretical calculations were carried out to evaluate the structural and charge distribution characteristics, including the optical, optoelectronics, density of states, transition density matrix, molecular electrostatic potential (ESP), reorganization energies, and photovoltaic properties. The results revealed that the designed series exhibited improved electron–hole pair coherences, efficient charge transportation, and favorable ESP patterns, suggesting their suitability for enhanced optical and electronic characteristics. Furthermore, the hole and electron overlap analyses demonstrated significant overlap in QM1–QM6, indicating efficient charge transfer and higher charge mobilities. Additionally, the analysis of reorganization energies showed low reorganization energy values, indicating favorable charge mobility rates and potential for high-efficiency solar cell devices. This research establishes a strong foundation for utilizing QI-containing fused units as central building blocks for designing high-performance acceptors, opening up new avenues for advancements in OSCs technology.

A Review: Application of Doped Hydrogenated Nanocrystalline Silicon Oxide in High Efficiency Solar Cell Devices.

Due to the unique microstructure of hydrogenated nanocrystalline silicon oxide (nc-SiOx:H), the optoelectronic properties of this material can be tuned over a wide range, which makes it adaptable to different solar cell applications. In this work, the authors review the material properties of nc-SiOx:H and the versatility of its applications in different types of solar cells. The review starts by introducing the growth principle of doped nc-SiOx:H layers, the effect of oxygen content on the material properties, and the relationship between optoelectronic properties and its microstructure. A theoretical analysis of charge carrier transport mechanisms in silicon heterojunction (SHJ) solar cells with wide band gap layers is then presented. Afterwards, the authors focus on the recent developments in the implementation of nc-SiOx:H and hydrogenated amorphous silicon oxide (a-SiOx:H) films for SHJ, passivating contacts, and perovskite/silicon tandem devices.

Optimisation and numerical analysis of highly efficient CGSe-based thin film solar cell

Among the various chalcopyrites compounds used in photovoltaic devices, Copper Gallium Selenium (CGSe) turns out as an underperformer due to its limited photovoltaic performance, So far highest efficiency measured is about 11.9%. This paper investigates the possibilities for efficiency enhancement for the CuGSe layer in Cu2O/CGSe/TiO2/ZnO thin film solar cell structure using the SCAPS-1D simulation program. The short circuit current (Jsc) and power conversion efficiency (PCE) is 30.77 mA cm−2 and 27.10%, with open-circuit voltage (Voc) and fill factor (FF) of 1.03 V and 84.72% respectively. Furthermore, we evaluated some specific parameters of TiO2/CGSe heterostructure, such as the influence of layer thickness, operating temperature, the effect of defect density and acceptor density of CGSe layer, metal work function, and the effect of series and shunt resistance on cell performance. We investigated that combining TiO2 as an ETL and Cu2O as HTL with a CGSe absorber layer is novel and promising, which results in higher power conversation efficiency and improves other PV parameters. The application of CGSe/TiO2 heterojunction in a simulated model offers a viable method for the development of high-efficiency solar cell 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.

Designing spiro-bifluorene core-based promising molecules with enhanced optoelectronic attributes for high efficiency solar cell devices

Organic solar cells are green and cost-effective alternatives to fulfill the energy requirements of conventional energy sources. They have grabbed the attention of the research community owing to their good power conversion efficiency. The aim of present research work was to increase the efficiency of previously synthesised reference (R) molecule. For this, eight new X-shaped molecules were successfully designed by structural modifications of Spiro-OMeTAD. Structural modifications of R were made by using 9,9’-spirobifuorene as a core material with eight different end-capped acceptor moieties. Among different DFT-based functionals, MPW1PW91 functional with 6-31G (d,p) basis set was selected to determine the optoelectronic properties. Interestingly, all newly designed molecules had a smaller energy gap (Egap), lower excitation energy (Ex) and greater absorption maxima (λmax) which illustrated the superior potential of the designed molecules (X1 to X8) than R. Among different molecules, X4 showed the most appropriate frontier molecular orbitals with the highest λmax (592.74 nm), best fill factor (86.43%), greater power conversion efficiency (10.04), improved open circuit voltage (0.83 eV) and the least Ex (2.09 eV). All newly created molecules showed better results than R, elucidating the potential of these modified Spiro-OMeTAD-based hole transport materials as pioneering materials in the fabrication of efficient next-generation SCs devices.

Laterally Grown Strain-Engineered Semitransparent Perovskite Solar Cells with 16.01% Efficiency

Hybrid organometallic halide perovskite-based semitransparent solar cell research has garnered significant attention recently due to their promising applications for smart windows, tandem devices, wearable electronics, displays, and sustainable internet-of-things. Though considerable progress has been made, stability, controlling the crystalline qualities, and growth orientation in perovskite thin films play crucial roles in improving the photovoltaic (PV) performance. Recently, strain modulation within the perovskite gathers an immense interest that is achieved by the ex situ process. However, little work is reported on in situ strain modulation, which is presented here. Apart from the challenges in the fabrication of high-efficiency perovskite solar cell (PSC) devices under ambient conditions, the stability of organic hole-transporting materials needs urgent attention. Herein, a single-step deposition of formamidiniumchloride (FACl)-mediated CH3NH3PbI3 (MAPbI3) thin films without an inert atmosphere and CuI as the inorganic hole-transporting material is demonstrated for their potential application toward semitransparent PSCs. The FACl amount in MAPbI3 (mg/mL) plays a critical role in controlling the crystallinity, growth orientations, and in situ strains, which modulate the charge carrier transport dynamics, thereby improving the efficiency of the PSC device. A photoconversion efficiency of 16.01% has been achieved from MAPbI3 with 20 mg/mL of FACl additive incorporation. The modification of the structural, electronic, and optical properties and the origin of strain in the as-synthesized MAPbI3 domains due to the addition of FACl are further validated with experimental findings in detail using density functional theory simulations.

Enhancement of hot carrier effect and signatures of confinement in terms of thermalization power in quantum well solar cell

A theoretical model using electron–phonon scattering rate equations is developed for assessing carrier thermalization under steady-state conditions in two-dimensional systems. The model is applied to investigate the hot carrier effect in III–V hot-carrier solar cells with a quantum well absorber. The question underlying the proposed investigation is: what is the power required to maintain two populations of electron and hole carriers in a quasi-equilibrium state at fixed temperatures and quasi-Fermi level splitting? The obtained answer is that the thermalization power density is reduced in two-dimensional systems compared to their bulk counterpart, which demonstrates a confinement-induced enhancement of the hot carrier effect in quantum wells. This power overall increases with the well thickness, and it is moreover shown that the intra-subband contribution dominates at small thicknesses while the inter-subband contribution increases with thickness and dominates in the bulk limit. Finally, the effects of the thermodynamic state of phonons and screening are clarified. In particular, the two-dimensional thermalization power density exhibits a non-monotonic dependence on the thickness of the quantum well layer, when both out-of-equilibrium longitudinal optical phonons and screening effects are taken into account. Our theoretical and numerical results provide tracks to interpret intriguing experimental observations in quantum well physics. They will also offer guidelines to increase the yield of photovoltaic effect based on the hot carrier effect using quantum well heterostructures, a result critical to the research toward high-efficiency solar cell devices.

Design and simulation of high efficiency lead-free heterostructure perovskite solar cell using SCAPS-1D

Perovskite materials still show a great interest in solar cell applications due to their promising performance. One of the prime candidates that have been widely investigated by several studies is CH3NH3PbI3. However, the toxicity of the lead used in this class of material limits its applications in large-scale perovskite solar cells industry, and force to search on alternative lead-free perovskite materials. In this paper, we designed and simulated a lead-free p-i-n type heterostructure perovskite solar cell formed from CH3NH3SnI3 as a i- and p-layer and CH3NH3SnCl3 as an n layer by employing the one-dimensional solar cell capacitance simulator (SCAPS-1D). The results show that a moderate thickness of 200 nm of the absorber layer is necessary for achieving a good cell efficiency. The simulations showed that high-doping concentration in the absorber layer is not desirable due to its influence in reducing the efficiency, and increasing the defect density in the absorber layer leads to deterioration in the device performance. In addition, a significant efficiency decrease was observed upon increasing the operating device temperature. Careful optimization of the device parameters has resulted in a significant improvement of the performance parameters and the optimal performance of the solar cell was obtained at PCE of 24.81 %, JSC of 28.11 mA/cm2, VOC of 1.00 V, and FF of 87.69 %. The simulated model concludes a great potential toward the fabrication of high-efficiency solar cell devices using lead-free perovskite materials.

Defect-mediated metastability and carrier lifetimes in polycrystalline (Ag,Cu)(In,Ga)Se2 absorber materials

Using a combination of optical and electrical measurements, we develop a model for metastable defects in Ag-alloyed Cu(In,Ga)Se2, one of the leading thin film photovoltaic materials. By controlling the pre-selenization conditions of the back contact prior to the growth of polycrystalline (Ag,Cu)(In,Ga)Se2 absorbers and subsequently exposing them to various stresses (light soaking and dark-heat), we explore the nature and role of metastable defects on the electro-optical and photovoltaic performance of high-efficiency solar cell materials and devices. Positron annihilation spectroscopy indicates that dark-heat exposure results in an increase in the concentration of the selenium–copper divacancy complex (VSe–VCu), attributed to depassivation of donor defects. Deep-level optical spectroscopy finds a corresponding increase of a defect at Ev + 0.98 eV, and deep-level transient spectroscopy suggests that this increase is accompanied by a decrease in the concentration of mid-bandgap recombination centers. Time-resolved photoluminescence excitation spectroscopy data are consistent with the presence of the VSe–VCu divacancy complex, which may act as a shallow trap for the minority carriers. Light-soaking experiments are consistent with the VSe–VCu optical cycle proposed by Lany and Zunger, resulting in the conversion of shallow traps into recombination states that limit the effective minority carrier recombination time (and the associated carrier diffusion length) and an increase in the doping density that limits carrier extraction in photovoltaic devices.

Enhance the performance of ZnO-based perovskite solar cells under ambient conditions

The ETL layer is used to transport electrons and block holes in the perovskite solar cell (PSC), and the uniformity of the dense layer affects the open circuit voltage (Voc) of the battery. The PSC open circuit voltage prepared by the solution method was 0.68 V, and the open circuit voltage of the PSC prepared by the sol method was remarkably improved to 0.95 V. The quality of the perovskite layer is critical for obtaining high-performance perovskite solar cells (PSC). In the process of preparing PSC by sequential deposition, the MAI solution was formed by IPA-n-hexane instead of isopropyl alcohol (IPA) as a solvent to grow CH3NH3PbI3(MAPI). The MAPI prepared by the mixed solvent was characterized by scanning electron microscopy (SEM). The mixed solvent inhibited the Oswald ripening process, and the perovskite layer showed a uniform and dense morphology. The PL characterization implied that the MAPI film with low defect concentration, which prepared from the mixed solvent. Compared to the single solvent PSC (PCE = 4.2%), the efficiency was significantly improved by 1.5 times to 6.2%. This study provides the possibility to prepare ZnO-based high-efficiency solar cell devices in the air.

Role of co-sensitization in dye-sensitized and quantum dot-sensitized solar cells

Novel materials for third generation solar cells have emerged as one of the major scientific contribution in alternative energy approaches. In this scenario, semiconductor nanomaterials and organic dye molecules have greatly acknowledged for their vast contribution to the solar energy applications. Research on semiconductor nanomaterials for fabricating future generation solar cells is still fascinating due to their extraordinary structural and optical properties. Moreover, functionalization of organic dye molecules helps to harvest large amount of photons in order to apply them for high efficiency solar cell devices. Various attempts have been made to improve efficiency of quantum dot-sensitized solar cells and dye-sensitized solar cells using semiconductor inorganic nanomaterials and organic/organometallic dye molecules. Out of these, co-sensitization has been looking as most promising approach to improve the efficiency considerably. A record of over 14% of efficiency has been achieved in recent years through co-sensitization strategy. The energy transfer process during co-sensitization is also a very crucial and interesting. This review deals about materials, methods, various approaches and role of co-sensitization in enhancing the efficiency of dye-sensitized and quantum dot sensitized solar cells. The critical issues existing in the co-sensitization approach are also elaborately discussed.

Cu2ZnSnSe4 based solar cells combining co-electrodeposition and rapid thermal processing

In this work, a fast two-step process combining co-electrodeposition of a CuZnSn precursor plus a reactive selenization step with a rapid thermal annealing to synthesize Cu2ZnSnSe4 thin films is presented. By tuning the electrochemical procedure is feasible to obtain with a short electrodeposition time (15 min) the precursor composition required for high efficiency solar cell devices. XRD characterization reveals that the precursor is mainly composed of binary Cu-Zn and Cu-Sn alloys that after thermal treatment completely react to form a kesterite thin film. Raman spectra and Raman mappings demonstrate that best quality kesterite films are obtained after selective chemical etching necessary to remove secondary phases, like ZnSe and SnSe, which are detrimental for solar cell performance. Best solar cells prototypes achieve efficiencies of 5% with a current density of 30.9 mA/cm2, an open circuit potential of 327 mV and a fill factor of 51.5%. The low value of open circuit voltage is attributed to the presence of voids and partial delamination observed in the Mo/Cu2ZnSnSe4 interface.

Photoexcitations dynamics in pristine low bandgap π-conjugated copolymers

We present a comprehensive review on the optical properties in pristine low bandgap copolymers, namely PTB7 and PDTP–DFBT, which are used as electron donors in copolymer/phenyl C71 butyric acid methyl ester blends for high efficiency solar cell devices. The copolymer backbone chain comprises of donor (D) and acceptor (A) moieties, which lower the band gap to the near-IR spectral region. Unlike traditional π-conjugated polymers in which the primary photoexcitations are singlet excitons (SE), in D–A copolymers we find at short times coexistence of two primary photoexcitation species, namely SE and triplet–triplet (TT) pairs, which are directly photogenerated upon photon absorption from the ground state within 300 fs, our transient time resolution. Using the transient magnetophotoinduced absorption (t-MPA) spectroscopy, we reveal the spin coupling between the SE and TT spin states from their correlated t-MPA responses. In addition, we show that the TT species dissociates into two individual triplet excitons (TE) in the picosecond time scale; however, the two-geminate TEs are entangled and maintain their spin coherence into the microsecond time domain.

An Optically Flat Conductive Outcoupler Using Core/Shell Ag/ZnO Nanochurros

Transparent conductive electrodes (TCEs) featuring a smooth surface are indispensable for preserving pristine electrical characteristics in optoelectronic and transparent electronic devices. For high-efficiency organic light emitting diodes (OLEDs), a high outcoupling efficiency, which is crucial, is only achieved by incorporating a wavelength-scale undulating surface into a TCE layer, but this inevitably degrades device performance. Here, an optically flat, high-conductivity TCE composed of core/shell Ag/ZnO nanochurros (NCs) is reported embedded within a resin film on a polyethylene terephthalate substrate, simultaneously serving as an efficient outcoupler and a flexible substrate. The ZnO NCs are epitaxially grown on the {100} planes of a pentagonal Ag core and the length of ZnO shells is precisely controlled by the exposure time of Xe lamp. Unlike Ag nanowires films, the Ag/ZnO NCs films markedly boost the optical tunneling of light. Green-emitting OLEDs (2.78 × 3.5 mm2 ) fabricated with the Ag/ZnO TCE exhibit an 86% higher power efficiency at 1000 cd m-2 than ones with an Sn-doped indium oxide TCE. A full-vectorial electromagnetic simulation suggests the suppression of plasmonic absorption losses within their Ag cores. These results provide a feasibility of multifunctional TCEs with synthetically controlled core/shell nanomaterials toward the development of high-efficiency LED and solar cell devices.

Review—Light Emission from Thin Film Solar Cell Materials: An Emerging Infrared and Visible Light Emitter

In the last decade, there have been extensive studies on fabrication and physics of thin-film solar cell materials and devices. Many high-efficiency solar cell devices have been developed, and the knowledge gained in these studies can be used advantageously to produce bright light-emitting devices. In this review, we summarize recent luminescence spectroscopic studies on new solar-cell materials and discuss their photocarrier dynamics with respect to efficient light emission.

Effect of Au nanoparticles on the performance of hybrid solar cells

Recently, organic/inorganic hybrid solar cells have been extensively studied as a means to fabricate low-cost, relatively high efficiency solar cell devices. Along this line of research, we report the observed enhancement in the power conversion efficiency of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on planar silicon (Si) hybrid heterojunction solar cell devices when incorporating gold (Au) nanoclusters in the PEDOT:PSS blend. The Au nanoclusters of size 3–5 nm were synthesized by wet chemical methods, and capped with 4-mercaptobenzoic acid (p-MBA). The power conversion efficiency (PCE) of the described structures with Au nanoclusters was measured to be 8.2%, which compares well to the PCE value of 7.3% for similar devices without the nanoclusters. The increased PCE of the devices is attributed to the measured increased electrical conductivity as well as near field plasmonic effects of the aforementioned films due to the incorporation of the Au nanoclusters, which is directly reflected in the improved fill factor and external quantum efficiency of the devices produced.

Radiative Thermal Annealing/in Situ X-ray Diffraction Study of Methylammonium Lead Triiodide: Effect of Antisolvent, Humidity, Annealing Temperature Profile, and Film Substrates

Organic–inorganic hybrid halide perovskites are one of the most promising emerging photovoltaic materials due to their high efficiency and potentially low processing cost. Here, we present a well-controlled, manufacturing relevant annealing method, radiative thermal annealing, for the methylammonium lead triiodide (MAPbI3) films formed by a solvent engineering process, with dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) as solvent and diethyl ether as the antisolvent. Radiative thermal annealing can produce high quality perovskite films, evidenced by high efficiency solar cell devices (∼18% power conversion efficiency), in a shorter time than the widely used hot plate annealing. Using in situ X-ray diffraction during the radiative annealing, we show that the role of the antisolvent is not to form an important intermediate compound (a PbI2-MAI-DMSO complex) by washing of the main solvent (DMF), but to achieve a pinhole free, uniform film of MAPbI3 with minimal intermediate compound. Importantly, we ...

Surface and Interface Aspects of Organometal Halide Perovskite Materials and Solar Cells.

The current challenges (e.g., stability, hysteresis, etc.) in organometal halide perovskite solar cell research are closely correlated with surfaces and interfaces. For instance, efficient generation of charges, extraction, and transport with minimum recombination through interlayer interfaces is crucial to attain high-efficiency solar cell devices. Furthermore, intralayer interfaces may be present in the form of grain boundaries within a film composed of the same material, for example, a polycrystalline perovskite layer. The adjacent grains may assume different crystal orientations and/or have different chemical compositions, which impacts charge excitation and dynamics and thereby the overall solar cell performance. In this Perspective, we present case studies to demonstrate (1) how surfaces and interfaces can impact material properties and device performance and (2) how these issues can be investigated by surface science techniques, such as scanning probe microscopy, photoelectron spectroscopy, and so forth. We end this Perspective by outlining the future research directions based on the reported results as well as the new trends in the field.