The fast developing semiconductor industry is pushing to shrink and speed up transistors. This trend requires us to understand carrier dynamics in semiconductor heterojunctions with both high spatial and temporal reso...The fast developing semiconductor industry is pushing to shrink and speed up transistors. This trend requires us to understand carrier dynamics in semiconductor heterojunctions with both high spatial and temporal resolutions. Recently, we have successfully set up a timeresolved photoemission electron microscopy (TR-PEEM), which integrates the spectroscopic technique to measure electron densities at specific energy levels in space. This instrument provides us an unprecedented access to the evolution of electrons in terms of spatial location, time resolution, and energy, representing a new type of 4D spectro-microscopy. Here in this work, we present measurements of semiconductor performance with a time resolution of 184 fs, electron kinetic energy resolution of 150 meV, and spatial resolution of about 150 nm or better. We obtained time-resolved micro-area photoelectron spectra and energy-resolved TR-PEEM images on the Pb island on Si(111). These experimental results suggest that this instrument has the potential to be a powerful tool for investigating the carrier dynamics in various heterojunctions, which will deepen our understanding of semiconductor properties in the submicron/nanometer spatial scales and ultrafast time scales.展开更多
A series of random terpolymers P2-P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol% and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor ...A series of random terpolymers P2-P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol% and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor （D-A） type copolymer PTBT-Th （P1）. All polymers showed similar molecular weight with number-average molecular weight （Mn） and weight-average molecular weight （Mw） in the range of （59-74） and （93-114） kg·mol-1, respectively, to ensure a fair comparison on the structure-property relationships. Compared with the control copolymer PTBT-Th, the random terpolymers exhibited enhanced absorption intensity in a wide range from 400 nm to 650 nm in both solution and film as well as in polymer/PC71BM blends. From grazing incident wide-angle X-ray diffraction （GIWAXS）, compared with the regularly alternated copolymer PTB7-Th, the random terpolymers demonstrated mild structural disorder with reduced （100） lamellar stacking and slightly weakened （010） π-π stacking for the polymers as well as slightly reduced PC71BM aggregation in polymer/PC71BM blends. However, the measured hole mobility for terpolymers （（1.20-3.73） × 10 -4 cm2·V-1·s-1） was evaluated to be comparable or even higher than 1.35 × 10 -4 cm2·V-1 ·s-1 of the alternative copolymer. Enhanced average power conversion efficiency （PCE） from 7.35% to 8.11% and 7.79% to 8.37% was observed in both conventional and inverted device architectures from copolymer P1 to terpolymers P4, while further increasing the 2,2-bithiophene feed ratio decreased the PCE.展开更多
The application of heavy-metal complexes in bulk-heterojunction（BHJ） solar cells is a promising new research field which has attracted increasing attention,due to their strong spin-orbit coupling for efficient singl...The application of heavy-metal complexes in bulk-heterojunction（BHJ） solar cells is a promising new research field which has attracted increasing attention,due to their strong spin-orbit coupling for efficient singlet to triplet intersystem crossing.This review article focuses on recent advances of heavy metal complex containing organic and polymer materials as photovoltaic donors in BHJ solar cells.Platinum-acetylide containing oligomersor and polymers have been firstly illustrated due to the good solubility,square planar structure,as well as the fairly strong Pt-Pt interaction.Then the cyclometalated Pt or Ir complex containing conjugated oligomers and polymers are presented in which the triplet organometallic compounds are embedded into the organic/polymer backbone either through cyclometalated main ligand or the auxiliary ligand.Pure triplet small molecular cyclometalated Ir complex are also briefly introduced.Besides the chemical modification,physical doping of cyclometalated heavy metal complexes as additives into the photovoltaic active layers is finally demonstrated.展开更多
基金supported by the National Key R&D Program (No.2018YFA0208700 and No.2016YFA0200602)the National Natural Science Foundation of China (No.21688102 and No.21403222)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDB17000000)the Youth Innovation Promotion Association of Chinese Academy of Sciences (No.2017224)
文摘The fast developing semiconductor industry is pushing to shrink and speed up transistors. This trend requires us to understand carrier dynamics in semiconductor heterojunctions with both high spatial and temporal resolutions. Recently, we have successfully set up a timeresolved photoemission electron microscopy (TR-PEEM), which integrates the spectroscopic technique to measure electron densities at specific energy levels in space. This instrument provides us an unprecedented access to the evolution of electrons in terms of spatial location, time resolution, and energy, representing a new type of 4D spectro-microscopy. Here in this work, we present measurements of semiconductor performance with a time resolution of 184 fs, electron kinetic energy resolution of 150 meV, and spatial resolution of about 150 nm or better. We obtained time-resolved micro-area photoelectron spectra and energy-resolved TR-PEEM images on the Pb island on Si(111). These experimental results suggest that this instrument has the potential to be a powerful tool for investigating the carrier dynamics in various heterojunctions, which will deepen our understanding of semiconductor properties in the submicron/nanometer spatial scales and ultrafast time scales.
基金financially supported by the the National Natural Science Foundation of China(No.61761136013)the Natural Science Foundation of Jiangsu Province(Nos.BK20160042 and BK20160990)+1 种基金DFG(392306670)the CSC for financial support
文摘A series of random terpolymers P2-P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol% and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor （D-A） type copolymer PTBT-Th （P1）. All polymers showed similar molecular weight with number-average molecular weight （Mn） and weight-average molecular weight （Mw） in the range of （59-74） and （93-114） kg·mol-1, respectively, to ensure a fair comparison on the structure-property relationships. Compared with the control copolymer PTBT-Th, the random terpolymers exhibited enhanced absorption intensity in a wide range from 400 nm to 650 nm in both solution and film as well as in polymer/PC71BM blends. From grazing incident wide-angle X-ray diffraction （GIWAXS）, compared with the regularly alternated copolymer PTB7-Th, the random terpolymers demonstrated mild structural disorder with reduced （100） lamellar stacking and slightly weakened （010） π-π stacking for the polymers as well as slightly reduced PC71BM aggregation in polymer/PC71BM blends. However, the measured hole mobility for terpolymers （（1.20-3.73） × 10 -4 cm2·V-1·s-1） was evaluated to be comparable or even higher than 1.35 × 10 -4 cm2·V-1 ·s-1 of the alternative copolymer. Enhanced average power conversion efficiency （PCE） from 7.35% to 8.11% and 7.79% to 8.37% was observed in both conventional and inverted device architectures from copolymer P1 to terpolymers P4, while further increasing the 2,2-bithiophene feed ratio decreased the PCE.
基金The Agro-Industry R and D Special Fund of China(973 Program,No.2015CB932200)the National Natural Science Foundation of China(No.21304047)+2 种基金NSF of Jiangsu Province(No.13KJB430017)Research Fund for the Doctoral Programof Higher Education(No.20133221120015)Synergetic Innovation Center for Organic Electronics and Information Displays for financial support
文摘The application of heavy-metal complexes in bulk-heterojunction（BHJ） solar cells is a promising new research field which has attracted increasing attention,due to their strong spin-orbit coupling for efficient singlet to triplet intersystem crossing.This review article focuses on recent advances of heavy metal complex containing organic and polymer materials as photovoltaic donors in BHJ solar cells.Platinum-acetylide containing oligomersor and polymers have been firstly illustrated due to the good solubility,square planar structure,as well as the fairly strong Pt-Pt interaction.Then the cyclometalated Pt or Ir complex containing conjugated oligomers and polymers are presented in which the triplet organometallic compounds are embedded into the organic/polymer backbone either through cyclometalated main ligand or the auxiliary ligand.Pure triplet small molecular cyclometalated Ir complex are also briefly introduced.Besides the chemical modification,physical doping of cyclometalated heavy metal complexes as additives into the photovoltaic active layers is finally demonstrated.
