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Structure–Function Relationships Of Fullerene Esters In Polymer Solar Cells: Unexpected Structural Effects On Lifetime And Efficiency, Michael Tro, Alexis Sarabia, Kyle J. Bandaccari, David Oparko, Emma Lewis, Maxwell J. Giammona, Justin Isaac, Parisa Tajalli-Tehrani Valverde, Grace E. Chesmore, Thorsteinn Adalsteinsson, Richard P. Barber Jr., Brian J. Mcnelis
Structure–Function Relationships Of Fullerene Esters In Polymer Solar Cells: Unexpected Structural Effects On Lifetime And Efficiency, Michael Tro, Alexis Sarabia, Kyle J. Bandaccari, David Oparko, Emma Lewis, Maxwell J. Giammona, Justin Isaac, Parisa Tajalli-Tehrani Valverde, Grace E. Chesmore, Thorsteinn Adalsteinsson, Richard P. Barber Jr., Brian J. Mcnelis
Physics
We report both transport measurements and spectroscopic data of polymer/fullerene blend photovoltaics using a small library of fullerene esters to correlate device properties with a range of functionality and structural diversity of the ester substituent. We observe that minor structural changes can lead to significant and surprising differences in device efficiency and lifetime. For example we have found that isomeric R-groups in the fullerene ester-based devices we have studied have dramatically different efficiencies. The characteristic lifetimes derived from both transport and spectroscopic measurements are generally comparable; however, some more rapid effects in specific fullerene esters are not observed spectroscopically. It …
Imaging The Oblique Propagation Of Electrons In Germanium Crystals At Low Temperature And Low Electric Field, R. A. Moffatt, Blas Cabrera, B. M. Corcoran, J. M. Kreikebaum, P. Redl, B. Shank, J. J. Yen, Betty A. Young, P. L. Brink, M. Cherry, A. Tomada, A. Phipps, B. Sadoulet, K. M. Sundqvist
Imaging The Oblique Propagation Of Electrons In Germanium Crystals At Low Temperature And Low Electric Field, R. A. Moffatt, Blas Cabrera, B. M. Corcoran, J. M. Kreikebaum, P. Redl, B. Shank, J. J. Yen, Betty A. Young, P. L. Brink, M. Cherry, A. Tomada, A. Phipps, B. Sadoulet, K. M. Sundqvist
Physics
Excited electrons in the conduction band of germanium collect into four energy minima, or valleys, in momentum space. These local minima have highly anisotropic mass tensors which cause the electrons to travel in directions which are oblique to an applied electric field at sub-Kelvin temperatures and low electric fields, in contrast to the more isotropic behavior of the holes. This experiment produces a full two-dimensional image of the oblique electron and hole propagation and the quantum transitions of electrons between valleys for electric fields oriented along the [0,0,1] direction. Charge carriers are excited with a focused laser pulse on one …