Conventional Silicon Solar Cells Research Articles

Investigating the influence of natural dye extracts from Ocimum gratissimum, Solanum melongena, Piper guineese, and their blend in the fabrication of perovskite solar cells

Perovskite solar cells (PSCs) represent a promising alternative to conventional silicon solar cells but face challenges like instability stemming from structural defects, environmental toxicity due to the selection of precursors and additives, and concerns regarding long-term reliability. To address these issues, we investigated the viability of cost-effective and eco-friendly PSCs by strategically incorporating natural dyes derived from indigenous plants, including Ocimum gratisimum, Solanum melongena, and Piper guineese, into the MAPbI3 perovskite crystal, using a two-step sequential drop-casting technique. The resulting perovskite films underwent comprehensive analysis for their structural, morphological, optical and elemental composition using an X-ray diffractometer (XRD), scanning electron microscopy (SEM), UV–visible spectrophotometer (UV–Vis) and energy dispersive X-ray microscopy (EDX). Performance evaluation was conducted through J-V curve analysis using a solar simulator. The XRD analysis revealed polycrystalline films with enhanced diffraction intensities corresponding to a hexagonal structure, and the UV–Vis analysis demonstrated substantial improvements in light absorption with improved optical properties. SEM studies provided crucial correlations between morphology and performance, with each sample exhibiting unique attributes, and EDX analysis confirmed essential elements within the films. The current density-voltage analysis demonstrated a 1.83 % power conversion efficiency (PCE) for the natural dye-doped device under air, surpassing the pristine device. This study advances the understanding of the synergies between natural dyes and perovskite materials, emphasizing their potential to enhance PSC efficiency. The findings underscore the considerations for designing and optimizing PSCs, paving the way for further exploration of natural dye-based approaches in sustainable photovoltaic technologies.

Passivating defects in SnO2 electron transport layer through SnF2 incorporation in perovskite solar cells

Metal halide perovskite solar cells have received a lot of attention from researchers because of their excellent performance, and their efficiency has increased rapidly over the past decade and is now comparable to that of conventional crystalline silicon solar cells. Perovskite solar cells (PSCs) are currently most commonly constructed with SnO2 as an electron transport layer (ETL). Nevertheless, its existence of bulk phase defects and surface defects pose an impediment to developing a higher level as the most favorable electron transport layer. This paper suggests an efficient technique to decrease the defects of SnO2 through incorporating a metal halide SnF2 in planar (n-i-p type) perovskite solar cells. Divalent Sn in SnF2 is easily oxidized to tetravalent Sn, leading to more conversion of divalent Sn to tetravalent Sn, which inhibits the formation of oxygen vacancies from the source. F replaces defective sites, passivates oxygen vacancy defects, and reduces the content of hydroxyl oxygen on the surface. Doping SnF2 enhances the conduction band value and conductivity of SnO2, making the energy levels of the ETL and perovskite interfaces more compatible. This eliminates energy barriers in charge transport. Consequently, the fill factor of planar PSCs that were prepared through SnO2:SnF2 ETL exhibited an increase from 80.01% to 82.12%. Furthermore, the efficiency of PCE underwent an improvement from 21.43% to 22.65%.

Recent advances in the approaches for improving the photovoltaic performance of porphyrin-based DSSCs.

Among other photovoltaic techniques including perovskite solar cells and organic solar cells, dye-sensitized solar cells (DSSCs) are considered to be a potential alternative to conventional silicon solar cells. Porphyrins are promising dyes with the properties of easy modification and superior light-harvesting capability. However, porphyrin dyes still suffer from a number of unfavorable aspects, which need to be addressed in order to improve the photovoltaic performance. This feature article briefly summarizes the recent progress in improving the Voc and Jsc of porphyrin-based DSSCs in terms of molecular engineering by modifying the porphyrin macrocycle, donor and acceptor moieties of the porphyrin dyes, coadsorption of the porphrin dyes with bulky coadsorbents like chenodeoxycholic acid (CDCA), and cosensitization of the porphyrin dyes with metal-free organic dyes. Notably, concerted companion (CC) dyes are described in detail, which have been constructed by linking a porphyrin dye subunit and a metal-free organic dye subunit with flexible alkoxy chains to achieve panchromatic absorption and concerted enhancement of Voc and Jsc. In one sentence, this article is expected to provide further insights into the development of high performance DSSCs through the design and syntheses of efficient porphyrin dyes and CC dyes in combination with device optimization to achieve simultaneously elevated Voc and Jsc, which may inspire and promote further progress in the commercialization of the DSSCs.

Luminescence coupling in 28.4%-efficient tandem solar cell utilizing 20.8%-efficient perovskite minimodule stacked on silicon cell

The total power conversion efficiency (PCE) of 28.4% with an aperture area of 64 cm2 on a four-terminal (4T) tandem solar cell with a 20.8% efficiency-semitransparent perovskite module (SPM) with a series interconnection structure and a conventional passivated emitter and rear cell type crystalline silicon solar cell is independently confirmed. This is the independently confirmed record PCE of a 4T perovskite and crystalline silicon tandem solar cell with a structure having the same active area for both top and bottom cells. The impact of the luminescence coupling monitored by the silicon solar cell in the 4T tandem solar cell was investigated based on electrical properties of the top SPM analyzed by a simple one-diode equivalent circuit model.

Perovskite Photovoltaics: Navigating Stability Challenges for Enhanced Efficiency

In the field of photovoltaics (PVs), perovskite‐based solar cells (PSCs) have become a game‐changing technology, boasting impressive improvements in cell efficiency and providing a promising substitute for conventional silicon, inorganic, and organic solar cells. Herein, the in‐depth analysis over the numerous stability problems that PSCs face, including both extrinsic problems like moisture, UV light, and temperature stability and intrinsic problems like hysteresis effects and metal–perovskite reactions, is examined. This article illuminates the cutting‐edge techniques used to improve PSC stability, thereby paving the way for their commercial viability. This review makes a significant contribution to the ongoing search for higher PV performance by offering a thorough analysis of the developments, challenges, and potential of perovskite‐based solar cells. It investigates printing methods, stability issues, uses, and the special qualities of perovskite materials, ultimately advancing comprehension and the creation of high‐efficiency PSCs.

Improving efficiency of silicon solar cells by integrating SiO2-coated lead-free Cs3Bi2Br9 perovskites quantum dots as luminescence down-shifting layer

Lead-based perovskite quantum dots (QDs) have promising applications in optoelectronic devices, but commercial applications are limited by the potential toxicity and poor stability of lead. Meanwhile, there are lattice, polarity, and thermal expansion coefficient mismatches in integrating semiconductor materials onto the surface of photoelectronic circuit devices, resulting in high-density defects limiting the reliability of photoelectronic devices. Therefore, there is a need to investigate perovskite alternatives that are non-toxic, stable, and can be effectively coupled to silicon photonic circuits. In this paper, lead-free perovskite Cs3Bi2Br9/SiO2 QDs were synthesized. The emission wavelength falls within the 400–560 nm range, exhibiting vibrant blue photoluminescence and demonstrating exceptional air stability for a duration exceeding 60 days. Optical tests and density-functional theory (DFT) calculations show that the silica shell layer effectively binds the electron and hole wave functions, prevents photon-generated carriers from escaping, reduces surface defects, and improves the carrier recombination probability. Meanwhile, using Cs3Bi2Br9/SiO2 QDs as a luminescent down-shifting (LDS) layer in combination with a conventional silicon solar cell, the photovoltaic conversion power was increased by 1.82%. Hence, the core-shell structure is designed by the green environmental protection method to control the improvement of the PL characteristics of QDs, which opens a window for the synthesis of new barrier materials in ethanol and water systems, making the Cs3Bi2Br9/SiO2 QDs have great potential for the application of novel optoelectronic devices in the future.

Exploring the impact of different annealing conditions on physical properties of CdSeTe thin films for solar cell absorber layer applications

The perovskite and Silicon based single junction solar cells certainly showed higher efficiency but the perovskite solar cells are highly degradable and unstable in environment whereas conventional Silicon solar cells are relatively costly. The CdTe absorber based thin film solar cells have attained efficiency of greater than 22% where doping of Selenium into the CdTe absorber layer seems to improve the photovoltaic performance. The CdCl2 treatment is proven to be critical process which induces the grain growth and recrystallization in CdSeTe films. Thus herein, air and CdCl2 annealing is performed over thermally evaporated CdSeTe thin films to seek out their applicability as an effective absorber for Cd-based thin film photovoltaics. The XRD diffractograms exposed the appearance of cubic phase with (111) preferred orientation where crystallite size is increased with annealing temperature. The optical absorbance is found to be altered with temperature of annealing and Tauc’s plots exhibited that bandgap is found to be changed in the range of 1.40–1.52 eV with increasing annealing temperature. Electrical analysis divulges Ohmic character of films where electrical resistivity and conductivity are affected by nature and temperature of post-deposition annealing. The EDS patterns confirmed the deposition of CdSeTe thin films and post deposition CdCl2 activation treatment. The FESEM images demonstrated alteration in surface morphology by grain growth where the grain size of CdSeTe films is increased from 70 nm to 235 nm with CdCl2 annealing temperature. The findings confirm that annealed CdSeTe thin films showed demanding behavior for solar cell devices as prominent light harvesting absorber layers.

Supramolecular Polyurethane "Ligaments" Enabling Room-Temperature Self-Healing Flexible Perovskite Solar Cells and Mini-Modules.

Flexible perovskite solar cells (F-PSCs) have emerged as promising alternatives to conventional silicon solar cells for applications in portable and wearable electronics. However, the mechanical stability of inherently brittle perovskite, due to residual lattice stress and ductile fracture formation, poses significant challenges to the long-term photovoltaic performance and device lifetime. In this paper, to address this issue, a dynamic "ligament" composed of supramolecular poly(dimethylsiloxane) polyurethane (DSSP-PPU) is introduced into the grain boundaries of the PSCs, facilitating the release of residual stress and softening of the grain boundaries. Remarkably, this dynamic "ligament" exhibits excellent self-healing properties and enables the healing of cracks in perovskite films at room temperature. The obtained PSCs have achieved power conversion efficiencies of 23.73% and 22.24% for rigid substrates and flexible substrates, respectively, also 17.32% for flexible mini-modules. Notably, the F-PSCs retain nearly 80% of their initial efficiency even after subjecting the F-PSCs to 8000 bending cycles (r = 2 mm), which can further recover to almost 90% of the initial efficiency through the self-healing process. This remarkable improvement in device stability and longevity holds great promise for extending the overall lifetime of F-PSCs.

Charge pumping in solar cell structure

Modern understanding of the material science of semiconductor silicon allowed the authors to propose a new concept of the so-called “charge pumping” in the structures of photovoltaic converters or solar cells. This paper presents theoretical estimates of the rate of separation and collection of light-generated charge carriers in the structures of conventional silicon solar cells and charge-pumped solar cells. Relatively cheaper so-called “solar silicon” of p-type conductivity is typically used in the industrial production of solar cells. This type of silicon is particularly prone to the formation of thermodonor centers. Partial or, at higher temperatures (about 400 °C), even complete overcompensation of the hole type of conductivity in the base region may occur as a result of prolonged heating. This paper presents an original model describing the local formation of n+ regions in the solar cell structure by the so-called “local photon annealing”. These regions were named “charge pumps”. Experimental data on the formation of n+ regions as a result of Li diffusion are reported as an experimental confirmation of the theoretical estimations made in this work. Comparative volt-ampere characteristics of experimental charge-pumped photovoltaic converters and conventional solar cells are presented, showing an up to 30% increase in the short-circuit current Js.c for the experimental structures under standard illumination (AM1.5). The proposed technological aspects of charge-pumped photovoltaic converter fabrication deliver a cheap process and can be implemented in the industrial production of solar cells with little effort.

Solution‐Processed PEDOT:PSS/p‐Si/ZnO Heterojunction Solar Cells

With the introduction of the concept of dopant‐free carrier‐selective contact for c‐Si photovoltaics, Si‐based heterojunction solar cells can greatly reduce production costs by optimizing the manufacturing process while maintaining high power conversion efficiency. Compared with processes that rely on complex vacuum equipment, low‐temperature solution processing has many advantages over conventional silicon solar cells. However, research on low‐cost and high‐efficiency solar cells based on p‐type crystalline silicon is relatively rare. From the point of view regards energy band matching, the inorganic metal oxide semiconductor material ZnO is well suited for low‐cost solution method studies due to its easy preparation, very high transmittance in the visible spectrum, low cost, and suitable energy levels matching p‐Si. Herein, ZnO is spin coated on the back of p‐Si to form a heterojunction, together with spin coating of PEDOT:PSS on the front side as the hole transport layer and passivation layer, a PEDOT:PSS/p‐Si/ZnO‐structured p‐Si‐based backcontact hybrid solar cell is successfully fabricated at low temperature (≤135 °C) via solution process with a PCE of 9.77% (Voc = 0.56 V, Jsc = 25.99 mA cm−2, fill factor = 67.10%). This work provides a promising approach for fabricating high‐performance and low‐cost silicon‐based heterojunction solar cells.

AC back surface recombination, as applied to determine (p) base thickness of both conventional and vertical series junction (n+/p/p+) silicon solar cells under white illumination

AC back surface recombination, as applied to determine (p) base thickness of both conventional and vertical series junction (n+/p/p+) silicon solar cells under white illumination

Ultra-thin Ag/Si heterojunction hot-carrier photovoltaic conversion Schottky devices for harvesting solar energy at wavelength above 1.1 µm

Traditional silicon solar cells can only absorb the solar spectrum at wavelengths below 1.1 μm. Here we proposed a breakthrough in harvesting solar energy below Si bandgap through conversion of hot carriers generated in the metal into a current using an energy barrier at the metal–semiconductor junction. Under appropriate conditions, the photo-excited hot carriers can quickly pass through the energy barrier and lead to photocurrent, maximizing the use of excitation energy and reducing waste heat consumption. Compared with conventional silicon solar cells, hot-carrier photovoltaic conversion Schottky device has better absorption and conversion efficiency for an infrared regime above 1.1 μm, expands the absorption wavelength range of silicon-based solar cells, makes more effective use of the entire solar spectrum, and further improves the photovoltaic performance of metal–silicon interface components by controlling the evaporation rate, deposition thickness, and annealing temperature of the metal layer. Finally, the conversion efficiency 3.316% is achieved under the infrared regime with a wavelength of more than 1100 nm and an irradiance of 13.85 mW/cm2.

Broadband Photon Harvesting in Organic Photovoltaic Devices Induced by Large-Area Nanogrooved Templates.

Thin-film organic photovoltaic (OPV) devices represent an attractive alternative to conventional silicon solar cells due to their lightweight, flexibility, and low cost. However, the relatively low optical absorption of the OPV active layers still represents an open issue in view of efficient devices that cannot be addressed by adopting conventional light coupling strategies derived from thick PV absorbers. The light coupling to thin-film solar cells can be boosted by nanostructuring the device interfaces at the subwavelength scale. Here, we demonstrate broadband and omnidirectional photon harvesting in thin-film OPV devices enabled by highly ordered one-dimensional (1D) arrays of nanogrooves. Laser interference lithography, in combination with reactive ion etching (RIE), provides the controlled tailoring of the height and periodicity of the silica grooves, enabling effective tuning of the anti-reflection properties in the active organic layer (PTB7:PCBM). With this strategy, we demonstrate a strong enhancement of the optical absorption, as high as 19% with respect to a flat device, over a broadband visible and near-infrared spectrum. The OPV device supported on these optimized nanogrooved substrates yields a 14% increase in short-circuit current over the corresponding flat device, highlighting the potential of this large-scale light-harvesting strategy in the broader context of thin-film technologies.

Demonstration of 12 Years Outdoor Working of Highly Durable Dye-Sensitized Solar Cell Modules Employing Hydrophobic Surface Passivation and Suppression of Biased Distribution of Iodine Ions

Dye-sensitized solar cells (DSCs) outperform conventional silicon solar cells in terms of weight and design flexibility. Therefore, besides standard rooftop installation, DSCs are suitable for new applications, including windows and walls. However, insufficient durability remains a critical issue, and outdoor working over 10 years is yet to be realized. In this study, we developed two approaches to improve the durability. The first involves hydrophobic surface passivation on the TiO2 surfaces by adopting alkylbenzimidazole (CnH2n+1BI) with long alkyl chains instead of the conventional additive (N-methylbenzimidazole) used for high open-circuit voltage in an ionic liquid-based electrolyte. The additive with a suitable alkyl-chain length (N-butylbenzimidazole and N-hexylbenzimidazole) notably improved the resistance against infiltrating water. The second approach refers to the DSC module arrangement. A unique problem of large-sized modules is that the I3– distribution often becomes biased over time, lowering the conversion efficiency. Horizontal module arrangements and/or the strip-shaped single cells in the modules solved this problem. By adopting these two approaches, we have demonstrated that the 10 cm × 11 cm-sized DSC modules have high durability to maintain 75% of their initial performance after the 12 year outdoor working test. This is the longest demonstrated lifetime for DSC modules outdoors.

Locally Available Natural Dyes for Dyesensitized Solar Cells

Different types of natural dyes are commonly used to fabricate dyesensitized solar cells which are cheaper, simpler, and environmentally friendlier than conventional crystalline silicon solar cells. This paper objectifies the performance of locally grown natural dyes from Dhaka, Bangladesh using a simple fabrication design. Four natural dyes were obtained separately from spinach, turmeric, pomegranate, and beetroot which contain chlorophyll, curcumin, anthocyanin, and betanin pigments respectively. Ultraviolet-visible spectroscopy illustrated the optical properties of these dyes diluted in ethanol. Spinach and turmeric extracts showed sharper absorption peaks which qualify them as better sensitizers than pomegranate and beetroot extracts. Photoanodes (of thickness 15-20 μm) were prepared by employing the doctor blade technique on fluorine-doped tin oxides using TiO2 nanoparticles of anatase form and graphite coated fluorine-doped tin oxides were used as counter electrodes. The photoelectric measurements of the fabricated cells were done under air mass (AM) 1.5 and power density of 100 mW/cm2. The fabricated cell of turmeric extracted dye showed the highest efficiency of 0.031% (Open circuit voltage, VOC = 380 mV, Short circuit current density, JSC = 0.234 mA/cm2) and the cell using beetroot extract gave the highest fill factor (FF) of about 50% among the prepared dyesensitized solar cells. DUJASE Vol. 7(1) 38-44, 2022 (January)

Derivatized photosensitizer for an improved performance of the dye-sensitized solar cell

In recent years, Dye-Sensitized Solar Cell (DSSC) has drawn enormous attention due to its advantages over conventional silicon solar cells in terms of technological, financial, and environmental sustainability. In this work, experimental and computational methods were employed to investigate the effect of derivatization of dyes—cyanoacetic acid derivatives of cinnamaldehyde (HB1) photosensitizers on the performance of the TiO2-based DSSCs. The optical properties and the functional groups of the two dyes were determined by using UV–vis spectrophotometer and FT-IR spectroscopy, respectively. The J-V characterization and power-conversion efficiency of dyes in TiO2-based DSSCs containing I-/I3- electrolyte, and Graphite-carbon based FTO-glass (counter electrode) were examined. The study revealed that the HB1 (derivatized dye) was shown to improve the DSSC performance compared to cinnamic acid (underivatized dye). The HOMO-LUMO energy bandgap was estimated using the density functional theory density (DFT) tool as implemented in Gaussian09 software with a basis set of B3LYP/6-31G (d, p) level of theory. The bandgap of dyes before and after derivatization were found to be 4.93 and 3.73 eV, respectively, higher than the bandgap of TiO2 (3.2 eV). HB1 offers the highest VOC, JSC, fill factor (%FF), and power-conversion efficiency of 0.48 V, 0.19 mA/cm2, 0.61, and 0.50 %, respectively. The study found that the derivatization technique greatly improved the conversion efficiency of the DSSCs by about 22 % in comparison to the cinnamic acid dye (0.39 %).

Estimating the potential for semitransparent organic solar cells in agrophotovoltaic greenhouses

Agrophotovoltaic is a considerably new solar sharing concept between photovoltaic energy generation and agricultural production. Agrophotovoltaic aims to promote solar energy while producing crops on the same land. Currently, agrophotovoltaics employ conventional silicon solar cells at a high cost. However, organic PV offers convenient features like panel flexibility, semitransparency and an easier fabrication route at a lower price. This work assesses and analyses the potential for semitransparent organic solar cells in agrophotovoltaic greenhouses. Semitransparent solar cells transform agrophotovoltaic from a solar sharing technology to selective solar spectrum utilization. Organic semitransparent cells with 9.4% power conversion efficiency and 24.6% average visible transmittance are employed to design the greenhouse. For evaluation, a 3D greenhouse model is designed to simulate and compare light interaction and crop growth with both traditional and semitransparent technologies. This case study used ground-measured weather data from Geraldton (Australia), a tomato growth model, and transmittance data from a semitransparent organic solar cell having PTB7-Th: IEICO-4F as the active layer. The simulation results show a 46% increase in dry ground weight of tomato crops with the semitransparent organic solar cell compared to the conventional Silicon cell agrophotovoltaic greenhouse. The simulation model shows reasonable coherence when implemented for two other locations. A thorough model analysis with economic sensitivity is performed to assess the potential usage of semitransparent solar cells in a greenhouse to yield better crop growth.

Nano-optical designs for high-efficiency monolithic perovskite–silicon tandem solar cells

Perovskite–silicon tandem solar cells offer the possibility of overcoming the power conversion efficiency limit of conventional silicon solar cells. Various textured tandem devices have been presented aiming at improved optical performance, but optimizing film growth on surface-textured wafers remains challenging. Here we present perovskite–silicon tandem solar cells with periodic nanotextures that offer various advantages without compromising the material quality of solution-processed perovskite layers. We show a reduction in reflection losses in comparison to planar tandems, with the new devices being less sensitive to deviations from optimum layer thicknesses. The nanotextures also enable a greatly increased fabrication yield from 50% to 95%. Moreover, the open-circuit voltage is improved by 15 mV due to the enhanced optoelectronic properties of the perovskite top cell. Our optically advanced rear reflector with a dielectric buffer layer results in reduced parasitic absorption at near-infrared wavelengths. As a result, we demonstrate a certified power conversion efficiency of 29.80%.

Screen-Printable Cu–Ag Core–Shell Nanoparticle Paste for Reduced Silver Usage in Solar Cells: Particle Design, Paste Formulation, and Process Optimization

Copper–silver (Cu–Ag) core–shell nanoparticles are promising for replacing the silver particles and flakes used in printed conductors in current solar cells since they deliver good conductivity, chemical stability, and optical performance, while also reducing the silver content, thus significantly impacting the cost. The bare nanoparticles offer excellent air stability thanks to the silver-covered copper structure. We demonstrate a screen-printable paste for use in solar cell conductor applications. We report a printed morphology and light reflection properties similar to those achieved with commercial silver pastes. The reported Cu–Ag core–shell paste is uniquely formulated with an epoxy binder and an aliphatic hardener, delivering significantly improved electrical conductivity, while simultaneously reducing the overall silver content by ∼36 wt %. This is attributable to the cross-linked polymeric structure, low-temperature conversion, and improved loading of conductive core–shell nanoparticles. As needed for contact formation in conventional top-contact silicon solar cells, the paste is additionally loaded with lead bisilicate and delivers conductivity on par with that of commercial silver paste. Thus, by combining the reduction of the silver content with excellent electronic and optical properties, this Cu–Ag nanoparticle-based paste becomes attractive for low-cost printed-conductor applications, including photovoltaics and electronics.

Recent Advances and Challenges in Light Conversion Phosphor Materials for Third-Generation Quantum-Dot-Sensitized Photovoltaics

Photovoltaic (PV) technologies have received tremendous attention for producing clean and renewable energy from the Sun. Third-generation quantum-dot-sensitized solar cells (QDSCs) present promising alternatives to conventional silicon solar cells due to their unique properties such as simplicity in fabrication, lower processing temperature, high flexibility, semitransparent nature, and a theoretical conversion efficiency of up to 44%. However, the light-harvesting QD materials used in these SCs allow for the absorption of a small portion (from 300 to 800 nm) of the solar spectrum due to their narrow band gap. The nonabsorption of UV and near-infrared (NIR) light limits the power conversion efficiency (PCE) of these SCs. Hence, a PV technique that efficiently uses the entire solar spectrum becomes essential. The incorporation of light conversion phosphor materials (LCs) in QDSCs is a promising technology to absorb the whole part of the solar spectrum and enhance the PCE of these SCs. This review presents an overview of the advantages and limitations of QDSCs, different types of lanthanide-based light conversion phosphor materials, their synthesis and light conversion mechanism, and their influence on QDSCs.