Formamidine lead triiodide(FAPbI_(3))perovskites have become the most promising photovoltaic materials for perovskite solar cells with record power conversion efficiency(PCE).However,random nucleation,phase transition...Formamidine lead triiodide(FAPbI_(3))perovskites have become the most promising photovoltaic materials for perovskite solar cells with record power conversion efficiency(PCE).However,random nucleation,phase transition,and lattice defects are still the key challenges limiting the quality of FAPbI_(3) films.Previous studies show that the introduction or adding of seeds in the precursor is effective to promote the nucleation and crystallization of perovskite films.Nevertheless,the seed-assisted approach focuses on heterogeneous seeds or hetero-composites,which inevitably induce a lattice-mismatch,the genera-tion of strain or defects,and the phase segregation in the perovskite films.Herein,we first demonstrate that high-quality perovskite films are controllably prepared using α-and δ-phases mixed FAPbI_(3) micro-crystal as the homogeneous seeds with the one-step antisolvent method.The partially dissolved seeds with suitable sizes improve the crystallinity of the perovskite flm with preferable orientation,improved carrier lifetime,and increased carrier mobility.More importantly,the α-phase-containing seeds promote the formation of α-phase FAPbI_(3) films,leading to the reduction of residual lattice strain and the suppres-sion of I-ion migration.Besides,the adding of dimethyl 2,6-pyridine dicarboxylate(DPD)into the pre-cursor further suppresses the generation of defects,contributing to the PCE of devices prepared in air ambient being significantly improved to 23.75%,among the highest PCEs for fully air-processed FAPbI_(3) solar cells.The unpackaged target devices possess a high stability,maintaining 80%of the initial PCE under simulated solar illumination exceeding 800 h.展开更多
Recently,hybrid organic-inorganic perovskite materials have drawn widespread attention because of their outstanding optoelectrical properties(i.e.,high absorption coefficient,long carrier diffusion distance),hence the...Recently,hybrid organic-inorganic perovskite materials have drawn widespread attention because of their outstanding optoelectrical properties(i.e.,high absorption coefficient,long carrier diffusion distance),hence they are suitable light-absorbing materials for photovoltaic application.Among all perovskite materials,formamidinium lead iodide(FAPbI3)based solar cells exhibit impressive power conversion efficiency(PCE)at laboratory stage,showing great potential to compete with silicon-based solar cell.However,FAPbI3 still suffers from poor phase stability which is the prior problem that needs to be addressed before its further commercialization.To be precise,the photoactive phase(αphase)is thermodynamically metastable at room temperature,which not only makesαphase tend to transform into photoinactive phase(δphase),but also causes competitive crystallization between two phases during the film preparation process,making it hard to fabricate pureα-FAPbI3 films.In our review,we summarized key factors that are vital for obtaining high-quality FAPbI3 perovskite thin films and enhancing the stability of FAPbI3 photoactive phase.First of all,precursor solution stability is of great importance since the conditions of precursor solution determine the nucleation and crystal growth process of perovskite.By introducing coordinating additives,using FAPbI3 single crystal as raw material or applying co-solution strategy,the impurities formed by side reaction during precursor solution aging can be effectively suppressed,thus the stability of FAPbI3 solution can be greatly prolonged.Second,the crystallization kinetics of FAPbI3 have been systematically manipulated to obtain dense and large grain size perovskite films.Through introducing intermediate phase,regulating the surface energy,and retarding the crystal growth of FAPbI3 in crystallization process,not only films without pinholes and fewer grain boundaries can be obtained,the pre-formedδphase at room temperature can also be well-suppressed,thus high-qualityα-FAPbI3 films can be obtained.Third,how to thermodynamically enhance the phase stability of acquired FAPbI3 film has been extensively studied.The Gibbs free energy of FAPbI3 photoactive phase can be reduced through composition engineering,dimension engineering and external additives engineering,hence the phase transition barrier fromαphase toδphase has been significantly improved,which further enhance the phase stability ofα-FAPbI3.Lastly,we pointed out challenges of each method and proposed potential applications of mentioned strategies on improving the stability of all kinds of perovskite materials,thus further boost the commercialization of perovskite solar cell devices.展开更多
The stabilization of the formamidinium lead iodide(FAPbI_(3))structure is pivotal for the development of efficient photovoltaic devices.Employing two-dimensional(2D)layers to passivate the threedimensional(3D)perovski...The stabilization of the formamidinium lead iodide(FAPbI_(3))structure is pivotal for the development of efficient photovoltaic devices.Employing two-dimensional(2D)layers to passivate the threedimensional(3D)perovskite is essential for maintaining the a-phase of FAPbI_(3) and enhancing the power conversion efficiency(PCE)of perovskite solar cells(PSCs).However,the role of bulky ligands in the phase management of 2D perovskites,crucial for the stabilization of FAPbI_(3),has not yet been elucidated.In this study,we synthesized nanoscale 2D perovskite capping crusts with<n>=1 and 2 Ruddlesden-Popper(RP)perovskite layers,respectively,which form a type-Ⅱ 2D/3D heterostructure.This heterostructure stabilizes the a-phase of FAPbI_(3),and facilitates ultrafast carrier extraction from the 3D perovskite network to transport contact layer.We introduced tri-fluorinated ligands to mitigate defects caused by the halide vacancies and uncoordinated Pb^(2+)ions,thereby reducing nonradiative carrier recombination and extending carrier lifetime.The films produced were incorporated into PSCs that not only achieved a PCE of 25.39%but also maintained 95%of their initial efficiency after 2000 h of continuous light exposure without encapsulation.These findings underscore the effectiveness of a phase-pure 2D/3D heterostructure-terminated film in inhibiting phase transitions passivating the iodide anion vacancy defects,facilitating the charge carrier extraction,and boosting the performance of optoelectronic devices.展开更多
Formamidinium lead triiodide(FAPbI_(3))perovskite quantum dots(PQDs)show great advantages in photovoltaic applications due to their ideal bandgap energy,high stability and solution processability.The anti-solvent used...Formamidinium lead triiodide(FAPbI_(3))perovskite quantum dots(PQDs)show great advantages in photovoltaic applications due to their ideal bandgap energy,high stability and solution processability.The anti-solvent used for the post-treatment of FAPbI_(3) PQD solid flms signifcantly afects the surface chemistry of the PQDs,and thus the vacancies caused by surface ligand removal inhibit the optoelectronic properties and stability of PQDs.Here,we study the efects of diferent anti-solvents with diferent polarities on FAPbI_(3) PQDs and select a series of organic molecules for surface passivation of PQDs.The results show that methyl acetate could efectively remove surface ligands from the PQD surface without destroying its crystal structure during the post-treatment.The benzamidine hydrochloride(PhFACl)applied as short ligands of PQDs during the post-treatment could fll the A-site and X-site vacancies of PQDs and thus improve the electronic coupling of PQDs.Finally,the PhFACl-based PQD solar cell(PQDSC)achieves a power conversion efciency of 6.4%,compared to that of 4.63%for the conventional PQDSC.This work provides a reference for insights into the surface passivation of PQDs and the improvement in device performance of PQDSCs.展开更多
The extreme instability of pureα-phase FAPbI_(3) under high humidity conditions restricts the highthroughput fabrication in unmodified air environments,resulting in poor performance ofα-phase FAPbI_(3) perovskite de...The extreme instability of pureα-phase FAPbI_(3) under high humidity conditions restricts the highthroughput fabrication in unmodified air environments,resulting in poor performance ofα-phase FAPbI_(3) perovskite devices obtained by scalable fabrication methods.Here we synthesized hyperbranched copper phthalocyanine(HCuPc)as a supramolecular additive with twisted phthalocyanine units to realize the molecular-level encapsulation at the grain boundaries through supramolecular interaction,which greatly broadened the processing window of FAPbI_(3) under high humidity.At the same time,unlike traditional encapsulation layer that carrier can only be collected by tunneling effect,the twisted phthalocyanine ring of HCu Pc in perovskite films is more conducive to hole extraction.Finally,a record efficiency was achieved in pure FAPbI_(3) based inverted structured solar cell by blade-coating to the best of our knowledge,even under unmodified humid air conditions(relative humidity of 65%–85%).The best operational stability of 3D pure FAPbI_(3) devices can also be achieved at the same time and unencapsulated HCuPc-FAPbI_(3) device can even operate with negligible degradation for 100 h in the open air(RH 30%–40%).展开更多
基金supported by the National Natural Science Foundation of China (61604131,62025403)the Natural Science Foundation of Zhejiang Province (LY19F040009)+1 种基金the Fundamental Research Funds of Zhejiang SciTech University (23062120-Y)the Open Project of Key Laboratory of Solar Energy Utilization and Energy Saving Technology of Zhejiang Province (ZJS-OP-2020-07)
文摘Formamidine lead triiodide(FAPbI_(3))perovskites have become the most promising photovoltaic materials for perovskite solar cells with record power conversion efficiency(PCE).However,random nucleation,phase transition,and lattice defects are still the key challenges limiting the quality of FAPbI_(3) films.Previous studies show that the introduction or adding of seeds in the precursor is effective to promote the nucleation and crystallization of perovskite films.Nevertheless,the seed-assisted approach focuses on heterogeneous seeds or hetero-composites,which inevitably induce a lattice-mismatch,the genera-tion of strain or defects,and the phase segregation in the perovskite films.Herein,we first demonstrate that high-quality perovskite films are controllably prepared using α-and δ-phases mixed FAPbI_(3) micro-crystal as the homogeneous seeds with the one-step antisolvent method.The partially dissolved seeds with suitable sizes improve the crystallinity of the perovskite flm with preferable orientation,improved carrier lifetime,and increased carrier mobility.More importantly,the α-phase-containing seeds promote the formation of α-phase FAPbI_(3) films,leading to the reduction of residual lattice strain and the suppres-sion of I-ion migration.Besides,the adding of dimethyl 2,6-pyridine dicarboxylate(DPD)into the pre-cursor further suppresses the generation of defects,contributing to the PCE of devices prepared in air ambient being significantly improved to 23.75%,among the highest PCEs for fully air-processed FAPbI_(3) solar cells.The unpackaged target devices possess a high stability,maintaining 80%of the initial PCE under simulated solar illumination exceeding 800 h.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.52125206,51972004)the National Key Research and Development Program of China(Grant No.2020YFB1506400)H.Z.acknowledges the support from the Tencent Foundation through the XRLORER PRIZE。
文摘Recently,hybrid organic-inorganic perovskite materials have drawn widespread attention because of their outstanding optoelectrical properties(i.e.,high absorption coefficient,long carrier diffusion distance),hence they are suitable light-absorbing materials for photovoltaic application.Among all perovskite materials,formamidinium lead iodide(FAPbI3)based solar cells exhibit impressive power conversion efficiency(PCE)at laboratory stage,showing great potential to compete with silicon-based solar cell.However,FAPbI3 still suffers from poor phase stability which is the prior problem that needs to be addressed before its further commercialization.To be precise,the photoactive phase(αphase)is thermodynamically metastable at room temperature,which not only makesαphase tend to transform into photoinactive phase(δphase),but also causes competitive crystallization between two phases during the film preparation process,making it hard to fabricate pureα-FAPbI3 films.In our review,we summarized key factors that are vital for obtaining high-quality FAPbI3 perovskite thin films and enhancing the stability of FAPbI3 photoactive phase.First of all,precursor solution stability is of great importance since the conditions of precursor solution determine the nucleation and crystal growth process of perovskite.By introducing coordinating additives,using FAPbI3 single crystal as raw material or applying co-solution strategy,the impurities formed by side reaction during precursor solution aging can be effectively suppressed,thus the stability of FAPbI3 solution can be greatly prolonged.Second,the crystallization kinetics of FAPbI3 have been systematically manipulated to obtain dense and large grain size perovskite films.Through introducing intermediate phase,regulating the surface energy,and retarding the crystal growth of FAPbI3 in crystallization process,not only films without pinholes and fewer grain boundaries can be obtained,the pre-formedδphase at room temperature can also be well-suppressed,thus high-qualityα-FAPbI3 films can be obtained.Third,how to thermodynamically enhance the phase stability of acquired FAPbI3 film has been extensively studied.The Gibbs free energy of FAPbI3 photoactive phase can be reduced through composition engineering,dimension engineering and external additives engineering,hence the phase transition barrier fromαphase toδphase has been significantly improved,which further enhance the phase stability ofα-FAPbI3.Lastly,we pointed out challenges of each method and proposed potential applications of mentioned strategies on improving the stability of all kinds of perovskite materials,thus further boost the commercialization of perovskite solar cell devices.
基金the Science and Technology Development Fund,Macao SAR(FDCT-0082/2021/A2,0010/2022/AMJ,0060/2023/RIA1,0136/2022/A3,006/2022/ALC,and EF044/IAPME-HG/2022/MUST)UM’s research fund(MYRG2022-00241IAPME,MYRG-GRG2023-00065-IAPME-UMDF,and MYRGCRG2022-00009-FHS)+8 种基金the research fund from Wuyi University(EF38/IAPME-XGC/2022/WYU)Shaanxi Fundamental Science Research Project for Mathematics and Physics(22JSY015 and 23JSY005)Shaanxi Province science and technology activities for overseas students selected funding project(2023015)the State Key Laboratory for Strength and Vibration of Mechanical Structures(SV2023-KF-18)Guangdong Provincial Key Laboratory of Semiconductor Optoelectronic Materials and Intelligent Photonic Systems(2023B1212010003)the China Fundamental Research Funds for the Central Universities,Young Talent Fund of Xi’an Association for Science and Technology(959202313020)the project of Innovative Team of Shaanxi Province(2020TD-001)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(NY223053)the National Natural Science Foundation of China(61935017,62105292,62175268,62288102 and 62304111)。
文摘The stabilization of the formamidinium lead iodide(FAPbI_(3))structure is pivotal for the development of efficient photovoltaic devices.Employing two-dimensional(2D)layers to passivate the threedimensional(3D)perovskite is essential for maintaining the a-phase of FAPbI_(3) and enhancing the power conversion efficiency(PCE)of perovskite solar cells(PSCs).However,the role of bulky ligands in the phase management of 2D perovskites,crucial for the stabilization of FAPbI_(3),has not yet been elucidated.In this study,we synthesized nanoscale 2D perovskite capping crusts with<n>=1 and 2 Ruddlesden-Popper(RP)perovskite layers,respectively,which form a type-Ⅱ 2D/3D heterostructure.This heterostructure stabilizes the a-phase of FAPbI_(3),and facilitates ultrafast carrier extraction from the 3D perovskite network to transport contact layer.We introduced tri-fluorinated ligands to mitigate defects caused by the halide vacancies and uncoordinated Pb^(2+)ions,thereby reducing nonradiative carrier recombination and extending carrier lifetime.The films produced were incorporated into PSCs that not only achieved a PCE of 25.39%but also maintained 95%of their initial efficiency after 2000 h of continuous light exposure without encapsulation.These findings underscore the effectiveness of a phase-pure 2D/3D heterostructure-terminated film in inhibiting phase transitions passivating the iodide anion vacancy defects,facilitating the charge carrier extraction,and boosting the performance of optoelectronic devices.
基金supported by the National Natural Science Foundation of China(Grant No.51872014)the Recruitment Program of Global Experts,Fundamental Research Funds for the Central Universities and the“111”project(B17002).
文摘Formamidinium lead triiodide(FAPbI_(3))perovskite quantum dots(PQDs)show great advantages in photovoltaic applications due to their ideal bandgap energy,high stability and solution processability.The anti-solvent used for the post-treatment of FAPbI_(3) PQD solid flms signifcantly afects the surface chemistry of the PQDs,and thus the vacancies caused by surface ligand removal inhibit the optoelectronic properties and stability of PQDs.Here,we study the efects of diferent anti-solvents with diferent polarities on FAPbI_(3) PQDs and select a series of organic molecules for surface passivation of PQDs.The results show that methyl acetate could efectively remove surface ligands from the PQD surface without destroying its crystal structure during the post-treatment.The benzamidine hydrochloride(PhFACl)applied as short ligands of PQDs during the post-treatment could fll the A-site and X-site vacancies of PQDs and thus improve the electronic coupling of PQDs.Finally,the PhFACl-based PQD solar cell(PQDSC)achieves a power conversion efciency of 6.4%,compared to that of 4.63%for the conventional PQDSC.This work provides a reference for insights into the surface passivation of PQDs and the improvement in device performance of PQDSCs.
基金supported by the National Natural Science Foundation of China(22179050,21875089,51973080)。
文摘The extreme instability of pureα-phase FAPbI_(3) under high humidity conditions restricts the highthroughput fabrication in unmodified air environments,resulting in poor performance ofα-phase FAPbI_(3) perovskite devices obtained by scalable fabrication methods.Here we synthesized hyperbranched copper phthalocyanine(HCuPc)as a supramolecular additive with twisted phthalocyanine units to realize the molecular-level encapsulation at the grain boundaries through supramolecular interaction,which greatly broadened the processing window of FAPbI_(3) under high humidity.At the same time,unlike traditional encapsulation layer that carrier can only be collected by tunneling effect,the twisted phthalocyanine ring of HCu Pc in perovskite films is more conducive to hole extraction.Finally,a record efficiency was achieved in pure FAPbI_(3) based inverted structured solar cell by blade-coating to the best of our knowledge,even under unmodified humid air conditions(relative humidity of 65%–85%).The best operational stability of 3D pure FAPbI_(3) devices can also be achieved at the same time and unencapsulated HCuPc-FAPbI_(3) device can even operate with negligible degradation for 100 h in the open air(RH 30%–40%).
