CH3NH3PbI3 perovskite solar cells with 2TPA-n-DP （TPA = 4,4＇-（（1E, I＇E,3E,3＇E）- [1,1＇-biphenyl]4,4＇-diylbis（buta-1,3-diene-4,1-diyl））; DP = bis（N,N-di-p-tolylaniline）; n = 1, 2, 3, 4） as hole-transporti...CH3NH3PbI3 perovskite solar cells with 2TPA-n-DP （TPA = 4,4＇-（（1E, I＇E,3E,3＇E）- [1,1＇-biphenyl]4,4＇-diylbis（buta-1,3-diene-4,1-diyl））; DP = bis（N,N-di-p-tolylaniline）; n = 1, 2, 3, 4） as hole-transporting materials （HTMs） have been fabricated. After optimization of the mesoporous TiO2 film thickness, devices based on 2TPA- 2-DP with power conversion efficiencies （PCEs） of up to 12.96% have been achieved, comparable to those of devices with （2,2＇,7,7＇-tetrakis（N,N-di-p- methoxyphenylamine）-9,9＇-spirobifluorene） （spiro-OMeTAD） as HTM under similar conditions. Further time-resolved photoluminescence （PL） measurements showed a fast charge transfer process at the perovskite/2TPA-2-DP interface. With the aid of electrochemical impedance spectra, a study of the electron blocking ability of 2TPA-2-DP in the device reveals that the presence of 2TPA-2-DP can greatly increase charge transfer resistance at the HTM/Au interface in the device, thus reducing the recombination. Furthermore, the perovskite solar cells based on these four HTMs exhibit ~ood stability after testin~ for one month.展开更多
As a route to improving the energy conversion of organic-inorganic hybrid-solar cells, we have tested the performance of poly(phenylene vinylene)(PPV), poly(2,5-thienylene vinylene)(PWTV) polymers and CdTe nanocrystal...As a route to improving the energy conversion of organic-inorganic hybrid-solar cells, we have tested the performance of poly(phenylene vinylene)(PPV), poly(2,5-thienylene vinylene)(PWTV) polymers and CdTe nanocrystal devices produced via aqueous-processing. It is found that small differences in the conformation of the sensitizer lead to dramatic effects on the solar cell efficiency. Using a combination of UV-Vis absorption spectroscopy and first-principles non-adiabatic molecular dynamics(NAMD) based on time-dependent density-functional theory(TDDFT), PPV is found to have a longer electron injection and recombination time despite seeming to have a better energy alignment with the substrate, which leads to a higher devices performance than PWTV. The present results shed new light on the understanding of organic-inorganic hybrid-solar cells and will trigger further experimental and theoretical investigations.展开更多
This article presents our experimental studies to unravel the dynamic photovoltaic processes occurring at donor:acceptor(D:A)and electrode:active layer(E:A)interfaces under device-operating conditions by using two uni...This article presents our experimental studies to unravel the dynamic photovoltaic processes occurring at donor:acceptor(D:A)and electrode:active layer(E:A)interfaces under device-operating conditions by using two unique magneto-optical measurements,namely photo-induced capacitance and magnetic field effect measurement.First,we have found that a higher surface polarization of dielectric thin film can decrease the surface charge accumulation at E:A interface.The photo-induced capacitance results indicate that dielectric thin film plays a crucial role in the charge collection in generating photocurrent in organic solar cells.Second,our experimental results from magnetic field effect show that the binding energies of charge transfer(CT)states at D:A interface can be evaluated by using the critical bias required to completely dissociate the CT states.This is the first experimental demonstration that the binding energies of CT states can be measured under deviceoperating conditions.Furthermore,we use our measurement of magnetic field effect to investigate the most popular organic photovoltaic solar cells,organometal halide perovskite photovoltaic devices.The results of magneto-photoluminescence show that the photogenerated electrons and holes are inevitably recombined into electron–hole pairs through a spin-dependent process in the perovskites.Therefore,using spin polarizations can present a new design to control the photovoltaic loss in perovskites-based photovoltaic devices.Also,we found that introducing D:A interface can largely affect the bulk charge dissociation and recombination in perovskite solar cells.This indicates that the interfacial and bulk photovoltaic processes are internally coupled in developing photovoltaic actions in perovskite devices.Clearly,these magneto-optical measurements show a great potential to unravel the deeper photovoltaic processes occurring at D:A and E:A interfaces in both organic bulk-heterojunction and perovskite solar cells under device-operating conditions.展开更多
文摘CH3NH3PbI3 perovskite solar cells with 2TPA-n-DP （TPA = 4,4＇-（（1E, I＇E,3E,3＇E）- [1,1＇-biphenyl]4,4＇-diylbis（buta-1,3-diene-4,1-diyl））; DP = bis（N,N-di-p-tolylaniline）; n = 1, 2, 3, 4） as hole-transporting materials （HTMs） have been fabricated. After optimization of the mesoporous TiO2 film thickness, devices based on 2TPA- 2-DP with power conversion efficiencies （PCEs） of up to 12.96% have been achieved, comparable to those of devices with （2,2＇,7,7＇-tetrakis（N,N-di-p- methoxyphenylamine）-9,9＇-spirobifluorene） （spiro-OMeTAD） as HTM under similar conditions. Further time-resolved photoluminescence （PL） measurements showed a fast charge transfer process at the perovskite/2TPA-2-DP interface. With the aid of electrochemical impedance spectra, a study of the electron blocking ability of 2TPA-2-DP in the device reveals that the presence of 2TPA-2-DP can greatly increase charge transfer resistance at the HTM/Au interface in the device, thus reducing the recombination. Furthermore, the perovskite solar cells based on these four HTMs exhibit ~ood stability after testin~ for one month.
基金supported by the National Natural Science Foundation of China(51433003)the National Basic Research Program of China(2014CB643503)
文摘As a route to improving the energy conversion of organic-inorganic hybrid-solar cells, we have tested the performance of poly(phenylene vinylene)(PPV), poly(2,5-thienylene vinylene)(PWTV) polymers and CdTe nanocrystal devices produced via aqueous-processing. It is found that small differences in the conformation of the sensitizer lead to dramatic effects on the solar cell efficiency. Using a combination of UV-Vis absorption spectroscopy and first-principles non-adiabatic molecular dynamics(NAMD) based on time-dependent density-functional theory(TDDFT), PPV is found to have a longer electron injection and recombination time despite seeming to have a better energy alignment with the substrate, which leads to a higher devices performance than PWTV. The present results shed new light on the understanding of organic-inorganic hybrid-solar cells and will trigger further experimental and theoretical investigations.
基金supported by the National Science Foundation of the United States(ECCS-1102011,ECCS-0644945,and CBET-1438181)the support from Sustainable Energy Education and Research Center and Center for Materials Processing at the University of Tennessee+1 种基金This research was partially conducted at the Center for Nanophase Materials Sciences based on user project(CNMS2012-106,CNMS2012-107,CNMS-2012-108),which is sponsored at Oak Ridge National Laboratory by the Division of Scientific User Facilities,U.S.Department of Energythe University of Tennessee also acknowledge the project support from the National Natural Science Foundation of China(21161160445,61077020)
文摘This article presents our experimental studies to unravel the dynamic photovoltaic processes occurring at donor:acceptor(D:A)and electrode:active layer(E:A)interfaces under device-operating conditions by using two unique magneto-optical measurements,namely photo-induced capacitance and magnetic field effect measurement.First,we have found that a higher surface polarization of dielectric thin film can decrease the surface charge accumulation at E:A interface.The photo-induced capacitance results indicate that dielectric thin film plays a crucial role in the charge collection in generating photocurrent in organic solar cells.Second,our experimental results from magnetic field effect show that the binding energies of charge transfer(CT)states at D:A interface can be evaluated by using the critical bias required to completely dissociate the CT states.This is the first experimental demonstration that the binding energies of CT states can be measured under deviceoperating conditions.Furthermore,we use our measurement of magnetic field effect to investigate the most popular organic photovoltaic solar cells,organometal halide perovskite photovoltaic devices.The results of magneto-photoluminescence show that the photogenerated electrons and holes are inevitably recombined into electron–hole pairs through a spin-dependent process in the perovskites.Therefore,using spin polarizations can present a new design to control the photovoltaic loss in perovskites-based photovoltaic devices.Also,we found that introducing D:A interface can largely affect the bulk charge dissociation and recombination in perovskite solar cells.This indicates that the interfacial and bulk photovoltaic processes are internally coupled in developing photovoltaic actions in perovskite devices.Clearly,these magneto-optical measurements show a great potential to unravel the deeper photovoltaic processes occurring at D:A and E:A interfaces in both organic bulk-heterojunction and perovskite solar cells under device-operating conditions.
