Even though the mesoporous-type perovskite solar cell (PSC) is known for high efficiency, its planar-type counterpart exhibits lower efficiency and hysteretic response. Herein, we report success in suppressing hysteresis and record efficiency for planar-type devices using EDTA-complexed tin oxide (SnO2) electron-transport layer. The Fermi level of EDTA-complexed SnO2 is better matched with the conduction band of perovskite, leading to high open-circuit voltage. Its electron mobility is about three times larger than that of the SnO2. The record power conversion efficiency of planar-type PSCs with EDTA-complexed SnO2 increases to 21.60% (certified at 21.52% by Newport) with negligible hysteresis. Meanwhile, the low-temperature processed EDTA-complexed SnO2 enables 18.28% efficiency for a flexible device. Moreover, the unsealed PSCs with EDTA-complexed SnO2 degrade only by 8% exposed in an ambient atmosphere after 2880 h, and only by 14% after 120 h under irradiation at 100 mW cm−2. The development of high efficiency planar-type perovskite solar cell has been lagging behind the mesoporous-type counterpart. Here Yang et al. modify the oxide based electron transporting layer with organic acid and obtain planar-type cells with high certified efficiency of 21.5% and decent stability.

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High efficiency planar-type perovskite solar cells with negligible hysteresis using EDTA-complexed SnO2

This review article examines the current state of understanding in how metal halide perovskite solar cells can degrade when exposed to moisture, oxygen, heat, light, mechanical stress, and reverse bias. It also highlights strategies for improving stability, such as tuning the composition of the perovskite, introducing hydrophobic coatings, replacing metal electrodes with carbon or transparent conducting oxides, and packaging. The article concludes with recommendations on how accelerated testing should be performed to rapidly develop solar cells that are both extraordinarily efficient and stable.

Understanding Degradation Mechanisms and Improving Stability of Perovskite Photovoltaics.

Improving the long-term stability of perovskite solar cells is critical to the deployment of this technology. Despite the great emphasis laid on stability-related investigations, publications lack consistency in experimental procedures and parameters reported. It is therefore challenging to reproduce and compare results and thereby develop a deep understanding of degradation mechanisms. Here, we report a consensus between researchers in the field on procedures for testing perovskite solar cell stability, which are based on the International Summit on Organic Photovoltaic Stability (ISOS) protocols. We propose additional procedures to account for properties specific to PSCs such as ion redistribution under electric fields, reversible degradation and to distinguish ambient-induced degradation from other stress factors. These protocols are not intended as a replacement of the existing qualification standards, but rather they aim to unify the stability assessment and to understand failure modes. Finally, we identify key procedural information which we suggest reporting in publications to improve reproducibility and enable large data set analysis. Reliability of stability data for perovskite solar cells is undermined by a lack of consistency in the test conditions and reporting. This Consensus Statement outlines practices for testing and reporting stability tailoring ISOS protocols for perovskite devices.

/pdf/consensus-statement-for-stability-assessment-and-reporting-37ng2o1dmx.pdf

Consensus statement for stability assessment and reporting for perovskite photovoltaics based on ISOS procedures

The solution of electromagnetic scattering by a homogeneous prolate (or oblate) spheroidal particle with an arbitrary size and refractive index is obtained for any angle of incidence by solving Maxwell's equations under given boundary conditions. The method used is that of separating the vector wave equations in the spheroidal coordinates and expanding them in terms of the spheroidal wavefunctions. The unknown coefficients for the expansion are determined by a system of equations derived from the boundary conditions regarding the continuity of tangential components of the electric and magnetic vectors across the surface of the spheroid. The solutions both in the prolate and oblate spheroidal coordinate systems result in a same form, and the equations for the oblate spheroidal system can be obtained from those for the prolate one by replacing the prolate spheroidal wavefunctions with the oblate ones and vice versa. For an oblique incidence, the polarized incident wave is resolved into two components, the TM mode for which the magnetic vector vibrates perpendicularly to the incident plane and the TE mode for which the electric vector vibrates perpendicularly to this plane. For the incidence along the rotation axis the resultant equations are given in the form similar to the one for a sphere given by the Mie theory. The physical parameters involved are the following five quantities: the size parameter defined by the product of the semifocal distance of the spheroid and the propagation constant of the incident wave, the eccentricity, the refractive index of the spheroid relative to the surrounding medium, the incident angle between the direction of the incident wave and the rotation axis, and the angles that specify the direction of the scattered wave.

Light Scattering by a Spheroidal Particle

There has been an enormous infusion of new ideas in the field of solar cells over the last 15 years; discourse on energy transfer has gotten much richer, and nanostructures and nanomaterials have revolutionized the possibilities for new technological developments. However, solar energy cannot become ubiquitous in the world's power markets unless it can become economically competitive with legacy generation methods such as fossil fuels. The new edition of Dr. Stephen Fonash's definitive text points the way toward greater efficiency and cheaper production by adding coverage of cutting-edge topics in plasmonics, multi-exiton generation processes, nanostructures and nanomaterials such as quantum dots. This book's new structure improves readability by shifting many detailed equations to appendices, and balances the first edition's semiconductor coverage with an emphasis on thin-films. Further, it now demonstrates physical principles with simulations in the well-known AMPS computer code developed by the author. This classic text is now updated with new advances in nanomaterials and thin films that point the way to cheaper, more efficient solar energy production and, many of the detailed equations from the first edition have been shifted to appendices in order to improve readability. It carries important theoretical points are now accompanied by concrete demonstrations via included simulations created with the well-known AMPS computer code.

太阳电池器件物理 = Solar cell device physics

Epitaxial layers of InSb have been grown on Si substrates by molecular beam epitaxy. Room‐temperature electron mobilities are 48 000 and 39 000 cm2/V s for 3.2 μm‐thick InSb with and without a thin GaAs buffer, respectively. The corresponding carrier concentrations are 2.2×1016 and 2.7×1016 cm−3. A sample with an InSb thickness of 8 μm exhibited room‐temperature mobilities as high as 55 000 cm2/V s with carrier concentrations of about 2.0×1016 cm−3. A sharp band‐edge transmission spectrum is observed at room temperature for the 8 μm layer.

Molecular beam epitaxial growth and characterization of InSb on Si

Analysis of Ion-Diffusion-Induced Interface Degradation in Inverted Perovskite Solar Cells via Restoration of the Ag Electrode

Over the past decade, colloidal quantum dot solar cells (CQD-SCs) have been developed rapidly, with their performances reaching over 16% power conversion efficiency. Accompanied by the development in materials engineering (CQD surface chemistry) and device physics (structures and defect engineering), CQD-SCs are moving towards commercialization. A broad overview of the requirements for commercialization is thus timely and imperative. Broad comprehension of structure engineering, upscaling techniques, stability and the manufacturing cost of CQD-SCs is necessary and should be established. In this review, the development of device structures is presented with their corresponding charge transfer mechanisms. Then, we overview the upscaling methods for the mass production of CQD-SCs. Comparisons between each of the upscaling techniques suggest the most advanced process close to industrialization. In addition, we have investigated the origin of the photovoltaic (PV) performance degradation. The possible degradation sources are categorized according to external environmental factors. Moreover, strategies for improving the stability of CQD-SCs are presented. In the conclusion, we have reviewed the cost-effectiveness of CQD-SCs in terms of the niche PV market. Step-wise manufacturing cost analysis for the commercial CQD-SCs is presented. In the conclusion, the future direction for environment-friendly CQD-SCs is discussed.

Towards the commercialization of colloidal quantum dot solar cells: perspectives on device structures and manufacturing

Plasmonic effects associated with localized surface plasmon (LSP) resonances such as strong light trapping, large scattering cross-section, and giant electric field enhancement have received much attention for the more efficient harvesting of solar energy. Notably, even as the thickness of the active layer is significantly reduced, the optical absorption capability of a solar cell could be maintained with the incorporation of plasmonic effects. This is especially important for the development of bulk heterojunction (BHJ) organic solar cells (OSCs), where the short exciton diffusion length, low carrier mobility, and strong charge recombination in organic materials strongly favors the use of optically thin active layers ( 100 nm), the optical absorption is alr...

Enhanced Light Trapping and Power Conversion Efficiency in Ultrathin Plasmonic Organic Solar Cells: A Coupled Optical-Electrical Multiphysics Study on the Effect of Nanoparticle Geometry

Low operational lifetime is a critical issue in perovskite light-emitting diodes. The forward-bias currents for light emission accelerate device degradation, which needs to be identified and unders...

Hyunho Lee

Papers

Molecular beam epitaxial growth and characterization of InSb on Si

Analysis of Ion-Diffusion-Induced Interface Degradation in Inverted Perovskite Solar Cells via Restoration of the Ag Electrode

Towards the commercialization of colloidal quantum dot solar cells: perspectives on device structures and manufacturing

Enhanced Light Trapping and Power Conversion Efficiency in Ultrathin Plasmonic Organic Solar Cells: A Coupled Optical-Electrical Multiphysics Study on the Effect of Nanoparticle Geometry

Direct Evidence of Ion-Migration-Induced Degradation of Ultrabright Perovskite Light-Emitting Diodes.