The emerging lead-free halide double perovskite solar cells have attracted widespread attentions due to their long-term stability and non-toxicity, but suffer from the low device performance. One efficiencylimiting fa...The emerging lead-free halide double perovskite solar cells have attracted widespread attentions due to their long-term stability and non-toxicity, but suffer from the low device performance. One efficiencylimiting factor is the improper contacts between the halide double perovskite and anode/cathode electrodes. Here, we improve the efficiency and stability of the bismuth-halide double perovskite based solar cells by a synergistic interface design for both electron and hole transport layers(ETL/HTL). The results show that the modification of the TiO_2 ETL with a thin hydrophobic C60 layer and replacement of the lithium-doped small molecule HTL with an un-doped conjugated polymer lead to higher surface quality of perovskite film and better energy-level alignment at the contacts. As a result, the optimized device shows reduced trap density, suppressed charge recombination and enhanced charge extraction, leading to an increase of 69% in device efficiency. In addition, the device also exhibits superior stability in ambient environment, heat stress and light bias after interface optimization. This work provides an efficient strategy for the device optimization of the emerging lead-free perovskite solar cells.展开更多
We demonstrate applications of a novel setup which is used for measuring the relative phase difference between S and P polarization at an oblique incidence point in optically denser medium by analyzing the relative fr...We demonstrate applications of a novel setup which is used for measuring the relative phase difference between S and P polarization at an oblique incidence point in optically denser medium by analyzing the relative frequency shift of adjacent axial modes of S and P resonances of a monolithic folded Fabry-Perot cavity (MFC). The relative phase difference at a reflection point A in an optically denser medium is inferred to be around -167.4°<span "=""> for a confocal cavity and -201.1° for a parallel cavity. Given the <i>n</i><sub>1</sub>, <i>n</i><sub>3</sub>, <i>φ</i><sub>1</sub>, <i>φ</i><sub>3</sub>, <i>λ</i></span><span "="">, and Δ, the elliptic formula tan(<i>ψ</i>)exp(<i>i</i>Δ) = <i>R<sub>p</sub></i>/<i>R<sub>s</sub></i> is used to find a solution for thickness d and refractive index </span><i>n</i><sub>2</sub><span "=""> of the thin film coated on point A, where <i>R<sub>s</sub></i> and <i>R<sub>p</sub></i> are total refractive index of <i>s</i> and<i> p</i> component of light related to two unknown values. Since it is hard to deduce an analytical solution for thickness and refractive index of the film, we firstly used exhaustion method to find the set of solution about thickness and refractive index when assumed there is no light absorption by the film and then Particle Swarm Optimization (PSO) to find a set of solution of thickness and complex refractive index which accounts the light absorption by the film.展开更多
Eco-friendly printing is important for mass manufacturing of thin-film photovoltaic(PV)devices to preserve human safety and the environment and to reduce energy consumption and capital expense.However,it is challengin...Eco-friendly printing is important for mass manufacturing of thin-film photovoltaic(PV)devices to preserve human safety and the environment and to reduce energy consumption and capital expense.However,it is challenging for perovskite PVs due to the lack of eco-friendly solvents for ambient fast printing.In this study,we demonstrate for the first time an eco-friendly printing concept for high-performance perovskite solar cells.Both the perovskite and charge transport layers were fabricated from eco-friendly solvents via scalable fast blade coating under ambient conditions.The perovskite dynamic crystallization during blade coating investigated using in situ grazing incidence wide-angle X-ray scattering(GIWAXS)reveals a long sol-gel window prior to phase transformation and a strong interaction between the precursors and the eco-friendly solvents.The insights enable the achievement of high quality coatings for both the perovskite and charge transport layers by controlling film formation during scalable coating.The excellent optoelectronic properties of these coatings translate to a power conversion efficiency of 18.26%for eco-friendly printed solar cells,which is on par with the conventional devices fabricated via spin coating from toxic solvents under inert atmosphere.The eco-friendly printing paradigm presented in this work paves the way for future green and highthroughput fabrication on an industrial scale for perovskite PVs.展开更多
基金supported by the National Key Research and DevelopmentProgramofChina(2016YFA0202403, 2017YFA0204800)the Key Program project of the National Natural Science Foundation of China (51933010)+3 种基金the National Natural Science Foundation of China (61604092, 61974085, 91733301)the National University Research Fund (GK201802005)the 111 Project (B14041)the National 1000 Talents Plan program (1110010341)。
文摘The emerging lead-free halide double perovskite solar cells have attracted widespread attentions due to their long-term stability and non-toxicity, but suffer from the low device performance. One efficiencylimiting factor is the improper contacts between the halide double perovskite and anode/cathode electrodes. Here, we improve the efficiency and stability of the bismuth-halide double perovskite based solar cells by a synergistic interface design for both electron and hole transport layers(ETL/HTL). The results show that the modification of the TiO_2 ETL with a thin hydrophobic C60 layer and replacement of the lithium-doped small molecule HTL with an un-doped conjugated polymer lead to higher surface quality of perovskite film and better energy-level alignment at the contacts. As a result, the optimized device shows reduced trap density, suppressed charge recombination and enhanced charge extraction, leading to an increase of 69% in device efficiency. In addition, the device also exhibits superior stability in ambient environment, heat stress and light bias after interface optimization. This work provides an efficient strategy for the device optimization of the emerging lead-free perovskite solar cells.
文摘We demonstrate applications of a novel setup which is used for measuring the relative phase difference between S and P polarization at an oblique incidence point in optically denser medium by analyzing the relative frequency shift of adjacent axial modes of S and P resonances of a monolithic folded Fabry-Perot cavity (MFC). The relative phase difference at a reflection point A in an optically denser medium is inferred to be around -167.4°<span "=""> for a confocal cavity and -201.1° for a parallel cavity. Given the <i>n</i><sub>1</sub>, <i>n</i><sub>3</sub>, <i>φ</i><sub>1</sub>, <i>φ</i><sub>3</sub>, <i>λ</i></span><span "="">, and Δ, the elliptic formula tan(<i>ψ</i>)exp(<i>i</i>Δ) = <i>R<sub>p</sub></i>/<i>R<sub>s</sub></i> is used to find a solution for thickness d and refractive index </span><i>n</i><sub>2</sub><span "=""> of the thin film coated on point A, where <i>R<sub>s</sub></i> and <i>R<sub>p</sub></i> are total refractive index of <i>s</i> and<i> p</i> component of light related to two unknown values. Since it is hard to deduce an analytical solution for thickness and refractive index of the film, we firstly used exhaustion method to find the set of solution about thickness and refractive index when assumed there is no light absorption by the film and then Particle Swarm Optimization (PSO) to find a set of solution of thickness and complex refractive index which accounts the light absorption by the film.
基金supported by the National Key Research and Development Program of China(2016YFA0202403,2017YFA0204800)the Key Program Project of the National Natural Science Foundation of China(51933010)+4 种基金the National Natural Science Foundation of China(61974085)the National University Research Fund(GK201802005)the 111 Project(B14041)the National 1000-Talent-Plan Program(1110010341)CHESS is supported by the NSF Award DMR-1332208.
文摘Eco-friendly printing is important for mass manufacturing of thin-film photovoltaic(PV)devices to preserve human safety and the environment and to reduce energy consumption and capital expense.However,it is challenging for perovskite PVs due to the lack of eco-friendly solvents for ambient fast printing.In this study,we demonstrate for the first time an eco-friendly printing concept for high-performance perovskite solar cells.Both the perovskite and charge transport layers were fabricated from eco-friendly solvents via scalable fast blade coating under ambient conditions.The perovskite dynamic crystallization during blade coating investigated using in situ grazing incidence wide-angle X-ray scattering(GIWAXS)reveals a long sol-gel window prior to phase transformation and a strong interaction between the precursors and the eco-friendly solvents.The insights enable the achievement of high quality coatings for both the perovskite and charge transport layers by controlling film formation during scalable coating.The excellent optoelectronic properties of these coatings translate to a power conversion efficiency of 18.26%for eco-friendly printed solar cells,which is on par with the conventional devices fabricated via spin coating from toxic solvents under inert atmosphere.The eco-friendly printing paradigm presented in this work paves the way for future green and highthroughput fabrication on an industrial scale for perovskite PVs.
