The John-Teller effect of the giant fullerene(GF)is studied.We find that in the giant fullerenes,the C-C bonds are dimerized,binding energies are decreased,energy gaps are enlarged,and the symmetries are reduced in th...The John-Teller effect of the giant fullerene(GF)is studied.We find that in the giant fullerenes,the C-C bonds are dimerized,binding energies are decreased,energy gaps are enlarged,and the symmetries are reduced in the metallic GF but not in the semiconducting GF.The dimerization patterns of these onions are presented.The distortions decrease as the number of carbon atoms on the GFs increases.展开更多
The narrow conduction band of C_(60) leads to the breakdown of the Migdal theorem and the McMillan formula is no longer applicable.In this letter,the second-order electron-phonon vertex correction is considered to exp...The narrow conduction band of C_(60) leads to the breakdown of the Migdal theorem and the McMillan formula is no longer applicable.In this letter,the second-order electron-phonon vertex correction is considered to explain the superconductivity in doped C_(60) solids and the transition temperature Tc thus obtained is in accordance with the experimental results.展开更多
Based on a full device model adopting three-dimensional Pauli master equation approach, the charge carrier loss process due to poor extraction channels between electrode and active layer in polymer bulk heterojunction...Based on a full device model adopting three-dimensional Pauli master equation approach, the charge carrier loss process due to poor extraction channels between electrode and active layer in polymer bulk heterojunction（BHJ） solar cells was studied. The influence of barrier height on device performance was simulated to reveal the importance of electrode improvement. It was found that relatively large extraction barrier height（over 0.40 eV） can lead to the significant diminishing of the overall charge collection efficiency, since bimolecular recombination rate would increase to a high level due to enhanced space charge accumulation effect near electrodes. In contrast, the percentage of charge carrier annihilated due to geminate recombination did not change significantly with barrier height variation. Our simulation results may provide the basis for a more accurate model and potential direction of polymer BHJ solar cells improvement.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘The John-Teller effect of the giant fullerene(GF)is studied.We find that in the giant fullerenes,the C-C bonds are dimerized,binding energies are decreased,energy gaps are enlarged,and the symmetries are reduced in the metallic GF but not in the semiconducting GF.The dimerization patterns of these onions are presented.The distortions decrease as the number of carbon atoms on the GFs increases.
基金the National Natural Science Foundation of China.
文摘The narrow conduction band of C_(60) leads to the breakdown of the Migdal theorem and the McMillan formula is no longer applicable.In this letter,the second-order electron-phonon vertex correction is considered to explain the superconductivity in doped C_(60) solids and the transition temperature Tc thus obtained is in accordance with the experimental results.
基金Supported by the National Natural Science Foundation of China（Nos.21174049, 91333103） and the Open Project of State Key Laboratory of Supramolecular Structure and Materials, China（No.201329）.
文摘Based on a full device model adopting three-dimensional Pauli master equation approach, the charge carrier loss process due to poor extraction channels between electrode and active layer in polymer bulk heterojunction（BHJ） solar cells was studied. The influence of barrier height on device performance was simulated to reveal the importance of electrode improvement. It was found that relatively large extraction barrier height（over 0.40 eV） can lead to the significant diminishing of the overall charge collection efficiency, since bimolecular recombination rate would increase to a high level due to enhanced space charge accumulation effect near electrodes. In contrast, the percentage of charge carrier annihilated due to geminate recombination did not change significantly with barrier height variation. Our simulation results may provide the basis for a more accurate model and potential direction of polymer BHJ solar cells improvement.
