Conventional titanium oxide(TiO2) as an electron transport layer(ETL) in hybrid organic-inorganic perovskite solar cells(PSCs) requires a sintering process at a high temperature to crystalize, which is not suitable fo...Conventional titanium oxide(TiO2) as an electron transport layer(ETL) in hybrid organic-inorganic perovskite solar cells(PSCs) requires a sintering process at a high temperature to crystalize, which is not suitable for flexible PSCs and tandem solar cells with their low-temperatureprocessed bottom cell. Here, we introduce a low-temperature solution method to deposit a TiO2/tin oxide(SnO2) bilayer towards an efficient ETL. From the systematic measurements of optical and electronic properties, we demonstrate that the TiO2/SnO2 ETL has an enhanced charge extraction ability and a suppressed carrier recombination at the ETL/perovskite interface, both of which are beneficial to photo-generated carrier separation and transport. As a result, PSCs with TiO2/SnO2 bilayer ETLs present higher photovoltaic performance of the baseline cells compared with their TiO2 and SnO2 single-layer ETL counterparts. The champion PSC has a power conversion efficiency(PCE) of 19.11% with an open-circuit voltage(Voc)of 1.15 V, a short-circuit current density(Jsc) of 22.77 mA cm^-2,and a fill factor(FF) of 72.38%. Additionally, due to the suitable band alignment of the TiO2/SnO2 ETL in the device, a high Vocof 1.18 V is achieved. It has been proven that the TiO2/SnO2 bilayer is a promising alternative ETL for high efficiency PSCs.展开更多
Emerging quantum dots(QDs)based light-emitting field-effect transistors(QLEFETs)could generate light emission with high color purity and provide facile route to tune optoelectronic properties at a low fabrication cost...Emerging quantum dots(QDs)based light-emitting field-effect transistors(QLEFETs)could generate light emission with high color purity and provide facile route to tune optoelectronic properties at a low fabrication cost.Considerable efforts have been devoted to designing device structure and to understanding the underlying physics,yet the overall performance of QLEFETs remains low due to the charge/exciton loss at the interface and the large band offset of a QD layer with respect to the adjacent carrier transport layers.Here,we report highly efficient QLEFETs with an external quantum efficiency(EQE)of over 20%by employing a dielectric-QDs-dielectric(DQD)sandwich structure.Such DQD structure is used to control the carrier behavior by modulating energy band alignment,thus shifting the exciton recombination zone into the emissive layer.Also,enhanced radiative recombination is achieved by preventing the exciton loss due to presence of surface traps and the luminescence quenching induced by interfacial charge transfer.The DQD sandwiched design presents a new concept to improve the electroluminescence performance of QLEFETs,which can be transferred to other material systems and hence can facilitate exploitation of QDs in a new type of optoelectronic devices.展开更多
基金supported by the National Key Research and Development of China (2018YFB1500103 and 2018YFB0704100)the National Natural Science Foundation of China (61574145, 61874177, 51502315 and 61704176)+1 种基金Zhejiang Provincial Natural Science Foundation (LR16F040002)Zhejiang Energy Group (znkj-2018-118)
文摘Conventional titanium oxide(TiO2) as an electron transport layer(ETL) in hybrid organic-inorganic perovskite solar cells(PSCs) requires a sintering process at a high temperature to crystalize, which is not suitable for flexible PSCs and tandem solar cells with their low-temperatureprocessed bottom cell. Here, we introduce a low-temperature solution method to deposit a TiO2/tin oxide(SnO2) bilayer towards an efficient ETL. From the systematic measurements of optical and electronic properties, we demonstrate that the TiO2/SnO2 ETL has an enhanced charge extraction ability and a suppressed carrier recombination at the ETL/perovskite interface, both of which are beneficial to photo-generated carrier separation and transport. As a result, PSCs with TiO2/SnO2 bilayer ETLs present higher photovoltaic performance of the baseline cells compared with their TiO2 and SnO2 single-layer ETL counterparts. The champion PSC has a power conversion efficiency(PCE) of 19.11% with an open-circuit voltage(Voc)of 1.15 V, a short-circuit current density(Jsc) of 22.77 mA cm^-2,and a fill factor(FF) of 72.38%. Additionally, due to the suitable band alignment of the TiO2/SnO2 ETL in the device, a high Vocof 1.18 V is achieved. It has been proven that the TiO2/SnO2 bilayer is a promising alternative ETL for high efficiency PSCs.
基金support from the National Natural Science Foundation of China(62174104,61735004,and 12174086)the National Key Research and Development Program of China(2016YFB0401702)the Shanghai Science and Technology Committee(19010500600)。
文摘Emerging quantum dots(QDs)based light-emitting field-effect transistors(QLEFETs)could generate light emission with high color purity and provide facile route to tune optoelectronic properties at a low fabrication cost.Considerable efforts have been devoted to designing device structure and to understanding the underlying physics,yet the overall performance of QLEFETs remains low due to the charge/exciton loss at the interface and the large band offset of a QD layer with respect to the adjacent carrier transport layers.Here,we report highly efficient QLEFETs with an external quantum efficiency(EQE)of over 20%by employing a dielectric-QDs-dielectric(DQD)sandwich structure.Such DQD structure is used to control the carrier behavior by modulating energy band alignment,thus shifting the exciton recombination zone into the emissive layer.Also,enhanced radiative recombination is achieved by preventing the exciton loss due to presence of surface traps and the luminescence quenching induced by interfacial charge transfer.The DQD sandwiched design presents a new concept to improve the electroluminescence performance of QLEFETs,which can be transferred to other material systems and hence can facilitate exploitation of QDs in a new type of optoelectronic devices.
