Enhancing the crystallinity and stability of perovskite solar cells with 4-tert-butylpyridine induction for efficiency exceeding 24%

Perovskite solar cells(PSCs)have emerged as a promising photovoltaic technology because of their high light absorption coefficient,long carrier diffusion distance,and tunable bandgap.However,PSCs face challenges such as hysteresis effects and stability issues.In this study,we introduced a novel approach to improve film crystallization by leveraging 4-tert-butylpyridine(TBP)molecules,thereby enhancing the performance and stability of PSCs.Our findings demonstrate the effective removal of PbI_(2)from the perovskite surface through strong coordination with TBP molecules.Additionally,by carefully adjusting the concentration of the TBP solution,we achieved enhanced film crystallinity without disrupting the perovskite structure.The TBP-treated perovskite films exhibit a low defect density,improved crystallinity,and improved carrier lifetime.As a result,the PSCs manufactured with TBP treatment achieve power conversion efficiency(PCE)exceeding 24%.Moreover,we obtained the PCE of 21.39%for the 12.25 cm^(2)module.

Enhancing performance of low-temperature processed CsPbI2Br all-inorganic perovskite solar cells using polyethylene oxide-modified TiO_(2)

CsPbX_(3)-based(X=I,Br,Cl)inorganic perovskite solar cells(PSCs)prepared by low-temperature process have attracted much attention because of their low cost and excellent thermal stability.However,the high trap state density and serious charge recombination between low-temperature processed TiO_(2)film and inorganic perovskite layer interface seriously restrict the performance of all-inorganic PSCs.Here a thin polyethylene oxide(PEO)layer is employed to modify TiO_(2)film to passivate traps and promote carrier collection.The impacts of PEO layer on microstructure and photoelectric characteristics of TiO_(2)film and related devices are systematically studied.Characterization results suggest that PEO modification can reduce the surface roughness of TiO_(2)film,decrease its average surface potential,and passivate trap states.At optimal conditions,the champion efficiency of CsPbI_(2)Br PSCs with PEO-modified TiO_(2)(PEO-PSCs)has been improved to 11.24%from 9.03%of reference PSCs.Moreover,the hysteresis behavior and charge recombination have been suppressed in PEO-PSCs.

Numerical Study and Optimization of CZTS-Based Thin-Film Solar Cell Structure with Different Novel Buffer-Layer Materials Using SCAPS-1D Software

This study explored the performances of CZTS-based thin-film solar cell with three novel buffer layer materials ZnS, CdS, and CdZnS, as well as with variation in thickness of buffer and absorber-layer, doping concentrations of absorber-layer material and operating temperature. Our aims focused to identify the most optimal thin-film solar cell structure that offers high efficiency and lower toxicity which are desirable for sustainable and eco-friendly energy sources globally. SCAPS-1D, widely used software for modeling and simulating solar cells, has been used and solar cell fundamental performance parameters such as open-circuited voltage (), short-circuited current density (), fill-factor() and efficiency() have been optimized in this study. Based on our simulation results, it was found that CZTS solar cell with Cd0.4Zn0.6S as buffer-layer offers the most optimal combination of high efficiency and lower toxicity in comparison to other structure investigated in our study. Although the efficiency of Cd0.4Zn0.6S, ZnS and CdS are comparable, Cd0.4Zn0.6S is preferable to use as buffer-layer for its non-toxic property. In addition, evaluation of performance as a function of buffer-layer thickness for Cd0.4Zn0.6S, ZnS and CdS showed that optimum buffer-layer thickness for Cd0.4Zn0.6S was in the range from 50 to 150nm while ZnS offered only 50 – 75 nm. Furthermore, the temperature dependence performance parameters evaluation revealed that it is better to operate solar cell at temperature 290K for stable operation with optimum performances. This study would provide valuable insights into design and optimization of nanotechnology-based solar energy technology for minimizing global energy crisis and developing eco-friendly energy sources sustainable and simultaneously.

Realization of High Efficient Ferroelectric Perovskite Nanoparticles in Biopolymer-Matrix Solar Cells under Low Lighting

The idea to use ferroelectric materials (PZN-PT) came from the fact that the ferroelectric nature could facilitate electric charges accumulation on the interfaces of the solar cell. Thus, it would increase the open circuit voltage Voc which could reach more than 10 V. This would directly impact the efficiency which is proportional to Voc, thus hoping to obtain solar efficiency never equaled by the halide perovskites which are less stable and less resistant in aggressive environments. In this work, the solar cells produced gave an exceptional record efficiency of 39.32% with a very high open circuit voltage (Voc) of 3.50 V, a short-circuit current density (Jsc) of 0.118 mA/cm2 and an FF of 0.72 measured in the positive polarization direction under 3825 lux (5.6 W/m2) lighting. The negative polarization direction under 4781 lux (7 W/m2) lightning gave a current density of 2 mA/cm2, an open circuit voltage of 2.30 V and an FF of 0.35.

Preparation and characterization of Cd_(1-x)Zn_xS buffer layers for thin film solar cells

Cd1_xZnxS （x = 0, 0.1, 0.2, 0.3, 1.0） thin films have been grown successfully on soda-lime glass substrates by chemical bath deposition technique as a very promising buffer layer material for optoelectronic device applications. The composition, structural properties, surface morphol- ogy, and optical properties of Cd~_xZnxS thin films were characterized by energy dispersive analysis of X-ray tech- nique （EDAX）, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and UV-Vis spectrophotometer tech- niques, respectively. The annealed films were observed to possess the deficient sulfur composition. The results of XRD show that the Cdl_xZnxS （x = 0. l） thin film annealed at 450 ~C forms hexagonal （wurtzite） structure with lattice parameters a = 0.408814 nm, c ： 0.666059 nm, and its average grain size is 24.9902 nm. The diffraction peaks become strong with the increasing annealing temperatures. The surface of Cdl_~ZnxS （x = 0.1） thin film annealed at 450 ~C is uninterrupted and homogenous as compared to other temperatures. From optical properties, it is observed that the presence of small amount of Zn results in marked changes in the optical band gap of CdS. The band gaps of the Cdl_xZnxS thin films vary from 2.42 to 3.51 eV as composition varies from x = 0.0 to 1.0.

Additives in metal halide perovskite films and their applications in solar cells

The booming growth of organic-inorganic hybrid lead halide perovskite solar cells have made this promising photovoltaic technology to leap towards commercialization.One of the most important issues for the evolution from research to practical application of this technology is to achieve high-throughput manufacturing of large-scale perovskite solar modules.In particular,realization of scalable fabrication of large-area perovskite films is one of the essential steps.During the past ten years,a great number of approaches have been developed to deposit high quality perovskite films,to which additives are introduced during the fabrication process of perovskite layers in terms of the perovskite grain growth control,defect reduction,stability enhancement,etc.Herein,we first review the recent progress on additives during the fabrication of large area perovskite films for large scale perovskite solar cells and modules.We then focus on a comprehensive and in-depth understanding of the roles of additives for perovskite grain growth control,defects reduction,and stability enhancement.Further advancement of the scalable fabrication of high-quality perovskite films and solar cells using additives to further develop large area,stable perovskite solar cells are discussed.

A Study on the Efficiency Gain of CsSnGeI3 Solar Cells with Graphene Doping

This paper presents a newly designed ultra-thin, lead-free, and all-inorganic solar cell structure. The structure was optimized using the SCAPS-1D simulator, incorporating solid-state layers arranged as n-graphene/CsSnGeI3/p-graphene. The objective was to investigate the potential of utilizing n-graphene as the electron transport layer and p-graphene as the hole transport layer to achieve maximum power conversion efficiency. Various materials for the electron transport layer were evaluated. The optimized cell structure achieved a maximum power conversion efficiency of 20.97%. The proposed solar cell structure demonstrates promising potential as an efficient, inorganic photovoltaic device. These findings provide important insights for developing and optimizing inorganic photovoltaic cells based on CsSnGeI3, with n-graphene electron transport layers and p-graphene hole transport layers.

Photovoltaic properties of Cu_2O-based heterojunction solar cells using n-type oxide semiconductor nano thin films prepared by low damage magnetron sputtering method

We improved the photovoltaic properties of Cu_2O-based heterojunction solar cells using n-type oxide semiconductor thin films prepared by a sputtering apparatus with our newly developed multi-chamber system. We also obtained the highest efficiency(3.21%) in an AZO/p-Cu_2O heterojunction solar cell prepared with optimized pre-sputtering conditions using our newly developed multi-chamber sputtering system. This value achieves the same or higher characteristics than AZO/Cu_2O solar cells with a similar structure prepared by the pulse laser deposition method.

Moth-eye Structured Polydimethylsiloxane Films for High-Efficiency Perovskite Solar Cells

Large-area polydimethylsiloxane(PDMS)films with variably sized moth-eye structures were fabricated to improve the efficiency of perovskite solar cells.An approach that incorporated photolithography,bilayer PDMS deposition and replication was used in the fabrication process.By simply attaching the moth-eye PDMS films to the transparent substrates of perovskite solar cells,the optical properties of the devices could be tuned by changing the size of the moth-eye structures.The device with 300-nm moth-eye PDMS films greatly enhanced power conversion efficiency of ~21 % due to the antireflective effect of the moth-eye structure.Furthermore,beautiful coloration was observed on the 1000-nm moth-eye PDMS films through optical interference caused by the diffraction grating effect.Our results imply that moth-eye PDMS films can greatly enhance the efficiency of perovskite solar cells and building-integrated photovoltaics.

Microstructure and optical properties of sprayed γ-CuI thin films for CuInS_2 solar cells

γ-CuI thin films were prepared by a spraying method using acetonitrile as a solvent,CuI and iodine as reagents.The influences of substrate temperature on the structure,topography,and optical properties of CuI films were investigated.Scanning electron microscope（SEM） photos revealed that the shape and grain size of CuI grains were related to substrate temperature.X-ray diffraction results showed that substrate temperature affected the crystalline quality of CuI films.When the substrate temperature was 110°C,CuI thin films showed γ-phase zinkblende structure with（111） preferred orientation.The dimension of the globular CuI crystallite was approximately 35 nm,the energy band gap was 2.97 eV,the maximum transmittance was 87.3% in the part of the visible region,and the open circuit voltage was close to 380 mV.This opened a route for a cadmium-free buffer layer for CuInS2 solar cells.

Research on the optimum hydrogenated silicon thin films for application in solar cells

Hydrogenated silicon （Si：H） thin films for application in solar ceils were deposited by using very high frequency plasma enhanced chemical vapour deposition （VHF PECVD） at a substrate temperature of about 170 ℃, The electrical, structural, and optical properties of the films were investigated. The deposited films were then applied as i-layers for p-i-n single junction solar cells. The current-voltage （I - V） characteristics of the cells were measured before and after the light soaking. The results suggest that the films deposited near the transition region have an optimum properties for application in solar cells. The cell with an i-layer prepared near the transition region shows the best stable performance.

Absorption enhancement in thin film a-Si solar cells with double-sided SiO_2 particle layers

Light absorption enhancement is very important for improving the power conversion efficiency of a thin film a-Si solar cell. In this paper, a thin-film a-Si solar cell model with double-sided SiO2 particle layers is designed, and then the underlying mechanism of absorption enhancement is investigated by finite difference time domain（FDTD） simulation;finally the feasible experimental scheme for preparing the SiO2 particle layer is discussed. It is found that the top and bottom SiO2 particle layers play an important role in anti-reflection and light trapping, respectively. The light absorption of the cell with double-sided SiO2 layers greatly increases in a wavelength range of 300 nm-800 nm, and the ultimate efficiency increases more than 22% compared with that of the flat device. The cell model with double-sided SiO2 particle layers reported here can be used in varieties of thin film solar cells to further improve their performances.

Preparation and Properties of CdTe Polycrystalline Films for Solar Cells

The structure and characteristics of CdTe thin filrns are closely dependent on the whole deposition process in close-space sublimation （CSS）. The physical mechanism of CSS was analyzed aud the temperature distribution in CSS system was measured, and the influences of the increasing-temperature process and pressure on the preliminary nucleus creation were studied. The resuits indicate ： tire samples deposited at different pressures hare a cubical structure of CdTe and the diffraction peaks of CdS and SnO2 ： F. As the atmosphere pressure increases, the crystal size of CdTe decreases, the rate of the transparency of the thin film decreases and the absorption side moves towards the short-wave direction. After a 4-minute depositing process with a substrate teraw.rature of 500℃ and a source temperature of 620 ℃, the polycostallinc thin films can be mmade , so the production of high-quality integrated cell with StrO2： F/ CdS/ CdTe/ Au structure is hopeful.

PEROVSKITE SEMICONDUCTOR OPTOELECTRONIC DEVICES Surface passivation of perovskite film for efficient solar cells

The power conversion efficiency (PCE) of perovskite solar cells (PSCs) swiftly increased from 3.8% to more than 20% during last 10 years, thanks to the advancement of perovskite film growth, device and interface engineering. However, solution-processed perovskites are usually polycrystalline, that is the photoactive films contain substantial structural disorders, such as grain boundaries, interfaces and crystallographic defects. These defects have detrimental impacts on the performance and stability of PSCs.

First-principles study on the alkali chalcogenide secondary compounds in Cu(In,Ga)Se_2 and Cu_2ZnSn(S,Se)_4 thin film solar cells

The beneficial effect of the alkali metals such as Na and K on the Cu（In.Ga）Se2 （CIGS） and Cu2ZnSn（S,Se）4 （CZTSSe） solar cells has been extensively investigated in the past two decades, however, in most of the studies the alkali metals were treated as dopants. Several recent studies have showed that the alkali metals may not only act as dopants but also form secondary phases in the absorber layer or on the surfaces of the films. Using the first-principles calculations, we screened out the most probable secondary phases of Na and K in CIGS and CZTSSe, and studied their electronic structures and optical properties. We found that all these alkali chalcogenide compounds have larger band gaps and lower VBM levels than CIGS and CZTSSe, because the existence of strong p-d coupling in CIS and CZTS pushes the valence band maximum （VBM） level up and reduces the band-gaps, while there is no such p-d coupling in these alkali chalcogenides. This band alignment repels the photo-generated holes from the secondary phases and prevents the electron-hole recombination. Moreover, the study on the optical properties of the secondary phases showed that the absorption coefficients of these alkali chalcogenides are much lower than those of CIGS and CZTSSe in the energy range of 0-3.4eV, which means that the alkali chalcogenides may not influence the absorption of solar light. Since the alkali metal dopants can passivate the grain boundaries and increase the hole carrier concentration, and meanwhile their related secondary phases have innocuous effect on the optical absorption and band alignment, we can understand why the alkali metal dopants can improve the CIGS and CZTSSe solar cell performance.

Inverted organic solar cells with solvothermal synthesized vanadium-doped TiO2 thin films as efficient electron transport layer

We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly（3-hexylthiophene） P3HT：[6-6] phenyl-（6） butyric acid methyl ester（PCBM）. 1% vanadium-doped TiO2nanoparticles were synthesized via the solvothermal method. Crystalline structure, morphology, and optical properties of pure and vanadium-doped TiO2 thin films were studied by different techniques such as x-ray diffraction, scanning electron microscopy, transmittance electron microscopy, and UV–visible transmission spectrum. The doctor blade method which is compatible with roll-2-roll printing was used for deposition of pure and vanadium-doped TiO2 thin films with thicknesses of 30 nm and 60 nm. The final results revealed that the best thickness of TiO2 thin films for our fabricated cells was 30 nm. The cell with vanadium-doped TiO2 thin film showed slightly higher power conversion efficiency and great Jsc of 10.7 mA/cm^2 compared with its pure counterpart. In the cells using 60 nm pure and vanadium-doped TiO2 layers, the cell using the doped layer showed much higher efficiency. It is remarkable that the external quantum efficiency of vanadium-doped TiO2 thin film was better in all wavelengths.

Comparing Crystalline Silicon Solar Cells with Thin Film

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Design of periodic metal-insulator-metal waveguide back structures for the enhancement of light absorption in thin-film solar cells

To increase the absorption in a thin layer of absorbing material （amorphous silicon, a-Si）, a light trapping design is presented. The designed structure incorporates periodic metal-insulator-metal waveguides to enhance the optical path length of light within the solar cells. The new design can result in broadband optical absorption enhancement not only for transverse magnetic （TM）-polarized light, but also for transverse electric （TE）-polarized light. No plasmonic modes can be excited in TE-polarization, but because of the coupling into the a-Si planar waveguide guiding modes and the diffraction of light by the bottom periodic structures into higher diffraction orders, the total absorption in the active region is also increased. The results from rigorous coupled wave analysis show that the overall optical absorption in the active layer can be greatly enhanced by up to 40%. The designed structures presented in this paper can be integrated with back contact technology to potentially produce high-efficiency thin-film solar cell devices.

Light scattering of nanocrystalline TiO_2 film used in dye-sensitized solar cells

This paper studies the light scattering and adsorption of nanocrystalline TiO2 porous films used in dye-sensitized solar cells composed of anatase and/or rutile particles by using an optical four-flux radiative transfer model. These light properties are difficult to measure directly on the functioning solar cells and they can not be calculated easily from the first-principle computational or quantitative theoretical evaluations. These simulation results indicate that the light scattering of 1 25 nm TiO2 particles is negligible, but it is effective in the range of 80 and 180 nm. A suitable mixture of small particles （10 nm radius）, which are resulted in a large effective surface, and of larger particles （150 nm radius）, which are effective light scatterers, have the potential to enhance solar absorption significantly. The futile crystals have a larger refractive index and thus the light harvest of the mixtures of such larger rutile and relatively small anatase particles is improved in comparison with that of pure anatase films. The light absorption of the 10μm double-layered films is also examined. A maximal light absorption of double-layered film is gotten when the thickness of the first layer of 10 urn-sized anatase particles is comparable to that of the second larger rutile layer.

Synthesis of the CuInSe_2 thin film for solar cells using the electrodeposition technique and Taguchi method

The Taguchi method was used to obtain the optimum electrodeposition parameters for the synthesis of the CuInSe2 thin film for solar cells. The parameters consist of annealing temperature, current density, CuCl2 concentration, FeCl3 concentration, H2SeO3 concentration, TEA amount, pH value, and deposition time. The experiments were carried out according to an L18（2^13^7） table An X-ray diffractometer （XRD） and a scanning electron microscope （SEM） were respectively used to analyze the phases and observe the microstructure and the grain size of the CuInSe2 film before and after annealing treatment. The results showed that the CuInSe2 phase was deposited with a preferred plane （112） parallel to the substrate surface. The optimum parameters are as follows： current density, 7 mA/cm^2; CuCl2 concentration, 10 mM; FeCl3 concentration, 50 mM; H2SeO3 concentration, 15 mM; TEA amount, 0 mL; pH value, 1.65; deposition time, 10 min; and annealing temperature, 500℃.