- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Upper limit to the photovoltaic efficiency of imperfect crystals from first principles
摘要： The Shockley-Queisser (SQ) limit provides a convenient metric for predicting light-to-electricity conversion efficiency of a solar cell based on the band gap of the light-absorbing layer. In reality, few materials approach this radiative limit. We develop a formalism and computational method to predict the maximum photovoltaic efficiency of imperfect crystals from first principles. The trap-limited conversion efficiency includes equilibrium populations of native defects, their carrier-capture coefficients, and the associated recombination rates. When applied to kesterite solar cells, we reveal an intrinsic limit of 20% for Cu2ZnSnSe4, which falls far below the SQ limit of 32%. The effects of atomic substitution and extrinsic doping are studied, leading to pathways for an enhanced efficiency of 31%. This approach can be applied to support targeted-materials selection for future solar-energy technologies.
关键词： recombination rates,kesterite solar cells,Shockley-Queisser limit,native defects,carrier-capture coefficients,photovoltaic efficiency
更新于2025-09-19 17:13:59
-
Stability, reliability, upscaling and possible technological applications of Kesterite solar cells
摘要： We review the stability and reliability results of Kesterite (Cu2ZnSn(S,Se)4, CZTSSe) based solar cells and we complete the reviewed data with additional as yet unpublished data on these matters. We also review published and new data on upscaling and the possible technological applications for this material. The Kesterite material is composed of mainly earth abundant elements and therefore very attractive for large scale applications. Stability data are so far quite scarce and the main results are the accelerated ageing tests carried out for the CZTSSe monograin technology, as well as yet unpublished data on long indoors and outdoors irradiance tests carried out on thin film CZTSSe technology deposited by a wet processing method. On upscaling and technological applications we point out the works on three main large scale photovoltaic technologies (monograin, in-line vacuum thin film, and wet-deposited thin film), as well as some work on water splitting applications.
关键词： applications,Cu2ZnSn(S,Se)4,Kesterite,stability,review,photovoltaics
更新于2025-09-19 17:13:59
-
Suppressed Deep Traps and Bandgap Fluctuations in Cu <sub/>2</sub> CdSnS <sub/>4</sub> Solar Cells with ≈8% Efficiency
摘要： The identification of performance-limiting factors is a crucial step in the development of solar cell technologies. Cu2ZnSn(S,Se)4-based solar cells have shown promising power conversion efficiencies in recent years, but their performance remains inferior compared to other thin-film solar cells. Moreover, the fundamental material characteristics that contribute to this inferior performance are unclear. In this paper, the performance-limiting role of deep-trap-level-inducing 2CuZn+SnZn defect clusters is revealed by comparing the defect formation energies and optoelectronic characteristics of Cu2ZnSnS4 and Cu2CdSnS4. It is shown that these deleterious defect clusters can be suppressed by substituting Zn with Cd in a Cu-poor compositional region. The substitution of Zn with Cd also significantly reduces the bandgap fluctuations, despite the similarity in the formation energy of the CuZn+ZnCu and CuCd+CdCu antisites. Detailed investigation of the Cu2CdSnS4 series with varying Cu/[Cd+Sn] ratios highlights the importance of Cu-poor composition, presumably via the presence of VCu, in improving the optoelectronic properties of the cation-substituted absorber. Finally, a 7.96% efficient Cu2CdSnS4 solar cell is demonstrated, which shows the highest efficiency among fully cation-substituted absorbers based on Cu2ZnSnS4.
关键词： DFT,kesterite,CZTS,bandgap fluctuations,antisite defects
更新于2025-09-19 17:13:59
-
Uncovering details behind the formation mechanisms of Cu <sub/>2</sub> ZnGeSe <sub/>4</sub> photovoltaic absorbers
摘要： Among the thin film chalcogenide photovoltaic community there is an increasing interest in the study of cationic and anionic substitution in the di?erent absorber materials, including CdTe, chalcopyrites – Cu(In,Ga)(S,Se)2 and kesterites – Cu2ZnSn(S,Se)4. In the last case, cationic substitution has been revealed as a key factor to solve or palliate to some extent part of the fundamental problems of the kesterite technology. Among the different possibilities, the partial or total substitution of Sn by Ge is one of the most promising options, with proved excellent results from very small up to almost complete replacement. In view of the relevance of Ge in kesterite, this work presents the complete analysis of the reaction formation of the Cu2ZnGeSe4 (CZGeSe) compound using a sequential process based on the sputtering of elemental stacked layers followed by reactive annealing under Se atmosphere, by implementing a break-off experiment. An unusual solid–liquid–vapor extended growth mechanism is observed, thanks to the previous formation of a eutectic GeSe9 liquid phase that melts at temperatures above 212 1C. Driven by this liquid phase, it is demonstrated that CZGeSe formation mechanisms follow a strict sequence, starting from more simple molecules (binary compounds), then evolving to the ternary one, and finally to the quaternary alloy which is formed through the reaction of Cu2GeSe3 and ZnSe solid phases. The relevance of the study is supported by the solar cells prepared with these absorbers, demonstrating conversion efficiency at the level of the best reports in the literature. Finally, possible strategies to manage this singular formation pathway are discussed.
关键词： Ge substitution,photovoltaic,Cu2ZnGeSe4,formation mechanisms,thin film,kesterite
更新于2025-09-19 17:13:59
-
[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Synthesis of Cu <sub/>2</sub> ZnSnSn <sub/>4</sub> nanoparticles for solar cell applications
摘要： Cu2ZnSnS4 are synthesized using hot injection method at different durations such as 3, 6, 9 and 12h. With increase in the duration to 6h, Cu3SnS4 phase appeared to be prominent together with CZTS phase. Fixing the deposition time at 3 h, the composition is varied to get a Cu poor sample Cu(Zn+Sn) ratio of 0.78 which is known to be in the optimum range for device fabricaton. These films showed tetragonal kesterite structure of CZTS with traces of wurtzite phase. Band gap varied from 1.55 to 1.3 eV and the nanoparticles have a size of ~ 8 nm. The optimized film had a resistivity of 15 (cid:2)(cid:2)cm and mobility of 8 cm2/Vs suitable for solar cells.
关键词： mobility,solar cell,kesterite,nanoparticle,Raman
更新于2025-09-16 10:30:52
-
Highlights in Applied Mineralogy || 4. Microstructure analysis of chalcopyrite-type Cu2ZnSe4 and kesterite-type Cu2ZnSnSe4 absorber layers in thin film solar cells
摘要： Thin film solar cells equipped with polycrystalline compound semiconductors as functional layer for light absorption have continuously been improved in terms of solar energy conversion efficiency, such that they became a competitive alternative to well-established silicon-based solar cells. In 1905, Einstein published a comprehensive, physical description of the photoelectric effect [1] and thus provided the theoretical framework for upcoming research of photovoltaic technologies. The emergence of photovoltaic devices, however, only started about 50 years later, and for several decades, it persisted a niche technology mainly for aerospace applications. Among others, silicon (Si) was known to belong to the group of (extrinsic) elemental semiconductors, and due to its abundance, it was the very first absorber material to be used in solar cells. Triggered by the oil crisis in the 1970s, the research of solar energy conversion technologies finally got a tremendous stimulus. As a result, research not only of silicon-based solar cells but also of other absorber layer materials based on compound semiconductors have been much more extensively endeavored. The latter were also brought into focus in order to address some severe drawbacks of silicon-based solar cells. First of all, the high energy consumption in fabricating single crystal silicon results in a quite long energy amortization time. In addition, the requirements on crystallinity and purity are extremely high while a considerable amount of material is wasted upon slicing silicon wafers. Also, during the growth of silicon single crystals a certain concentration of dopants has to be incorporated in order to induce either extrinsic p-type or n-type conductivity. Despite the energy of the band gap of silicon fitting quite well with the optimal energy determined by the solar spectrum, silicon is an indirect semiconductor whose photonic electron transition from the valence band to the conduction band needs to be assisted by a phononic momentum transfer. This requirement of coincidence between a photon of appropriate energy being absorbed and a phonon transferring impulse to the electron leads to a reduced probability of events of photoelectric charge carrier generation. Correspondingly, the absorber thickness must be augmented in order to compensate the low absorption coefficient. These aforementioned issues, eventually, gave rise to reconsider photovoltaic technologies, being both economical and ecological reasonably applicable in a more widely spread manner. These demands have paved the way for thin film solar cell technologies using compound semiconductors. Those compound semiconductors are intrinsically conductive, and they possess a higher absorption coefficient due to direct electron band transitions (Fig. 4.1).
关键词： kesterite-type,chalcopyrite-type,absorber layer materials,light absorption,microstructure analysis,photovoltaic technologies,solar energy conversion efficiency,compound semiconductors,thin film solar cells,silicon-based solar cells
更新于2025-09-16 10:30:52
-
Synthesis of Cu <sub/>2</sub> ZnSnSe <sub/>4</sub> from nitrate and selenite inks for use as an absorbent layer in the design of solar cells
摘要： This research was conducted to identify two acceptable precursors and methods of synthesis for the manufacture of photovoltaic cells. The kesterite Cu2ZnSnSe4, a promising material for solar cell applications, was synthesized from metal salts of Cu, Zn, Sn, and Se, by two low-cost routes: the direct dissolution of metal nitrates, and coprecipitation of selenites. In both cases, inks were obtained and deposited as thin-films by the Doctor Blade technique on glass substrates coated with molybdenum. The films were annealed in an oven at 550°C by 30 minutes. The phases of each thin film were analyzed by X-ray diffraction and Raman scattering. The morphology and the thickness of the layers were observed using a scanning electron microscope. The optical band gap was determined by ultraviolet-visible spectroscopy and the Tauc equation. The results confirmed the main phase of kesterite material, consistent with a tetragonal crystalline system oriented along the plane (1 1 2). These values are consistent with those found by Raman spectroscopy, where the main vibrational mode was identified at 173 cm-1 and 196 cm-1, characteristic of mode A vibration, and 243 cm-1 of mode B vibration; typical of kesterite. Simultaneously, a band gap of 0.89 eV was identified. These results demonstrate the effectiveness of the selenite′s coprecipitation method for synthesis of kesterite, without evidence of secondary phases. This determines the possibility of using this material in solar cell applications.
关键词： solar cells,Cu2ZnSnSe4,selenite coprecipitation,Doctor Blade technique,kesterite
更新于2025-09-16 10:30:52
-
Engineering of effective back-contact barrier of CZTSe: Nanoscale Ge solar cells – MoSe2 defects implication
摘要： Using temperature-dependent measurements and device modeling, we systematically study the e?ective back-contact barrier of CZTSe devices to improve the property of the back-contact interface. By comparing with CZTSe devices with various nanoscale Ge con?gurations, CZTSe nanoscale Ge bi-layers devices show the improved power conversion e?ciency by 1.1%. DC magnetron sputtering is used to fabricate CZTSe: nanolayer Ge devices. Critical device parameters are characterized to understand the impact of nanoscale Ge ?lms on the back-contact device characteristics. Based on empirical results, modeling is performed for the in?uence of MoSe2 defects on the e?ective back-contact barrier. Analysis of experimental results of Ge bi-layers devices with the improved back-contact barrier makes a good agreement with modeling and Sentaurus TCAD simulation at the 95% con?dence-level. The conversion e?ciency of CZTSe: nanoscale Ge bi-layers devices is improved up to 8.3%.
关键词： Schottky barrier,Thin ?lm solar cells,CZTSe,Kesterite,Back-contact,Ge nanolayer
更新于2025-09-12 10:27:22
-
Real-Time Electron Nanoscopy of Photovoltaic Absorber Formation from Kesterite Nanoparticles
摘要： Cu2ZnSnS4 nanocrystals are annealed in a Se-rich atmosphere inside a transmission electron microscope. During the heating phase, a complete S-Se exchange reaction occurs while the cation sublattice and morphology of the nanocrystals are preserved. At the annealing temperature, growth of large Cu2ZnSnSe4 grains with increased cation ordering is observed in real-time. This yields an annealing protocol which is transferred to an industrially-similar solar cell fabrication process resulting in a 33% increase in the device open circuit voltage. The approach can be applied to improve the performance of any photovoltaic technology that requires annealing because of the criticality of the process step.
关键词： cation ordering,Kesterite,photovoltaics,in situ transmission electron microscopy (TEM),annealing
更新于2025-09-12 10:27:22
-
TaS <sub/>2</sub> Back Contact Improving Oxide-Converted Cu <sub/>2</sub> BaSnS <sub/>4</sub> Solar Cells
摘要： Solar cells based on the wide band-gap Cu2BaSnS4 (CBTS) photoabsorber have achieved open circuit voltages up to 1.1 V over a short development period, making CBTS an attractive material for tandem photovoltaic and photoelectrochemical cells. In this work, we explore an alternative CBTS growth route based on oxide precursors, and we propose TaS2 as an alternative back contact material to the commonly used Mo/MoS2. The oxide precursor route does not require higher sulfurization temperatures than other more common fabrication routes, and it yields CBTS films with negligible Stokes shift between photoluminescence maximum and band gap energy, while at the same time avoiding sulfur contamination of vacuum systems. The high work-function metallic TaS2 compound is selected as a prospective hole-selective contact, which could also prevent the losses associated with carrier transport across the semiconducting MoS2 layer. By comparing CBTS solar cells with Mo and TaS2 back contacts, the latter shows a significantly lower series resistance, resulting in a 10% relative efficiency improvement. Finally, we fabricate a proof-of-concept monolithic CBTS/Si tandem cell using a thin Ti(O,N) interlayer intended both as a diffusion barrier and as a recombination layer between the two subcells.
关键词： wide band gap absorber,back contact,kesterite,cation substitution,tandem solar cell,silicon,TaS2,sputtering
更新于2025-09-12 10:27:22