tailieunhanh - Báo cáo hóa học: " Ultrafast Dynamics of Localized and Delocalized Polaron Transitions in P3HT/PCBM Blend Materials: The Effects of PCBM Concentration"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Ultrafast Dynamics of Localized and Delocalized Polaron Transitions in P3HT/PCBM Blend Materials: The Effects of PCBM Concentration | Nanoscale Res Lett 2009 4 1475-1480 DOI S11671-009-9423-6 NANO EXPRESS Ultrafast Dynamics of Localized and Delocalized Polaron Transitions in P3HT PCBM Blend Materials The Effects of PCBM Concentration Emmanouil Lioudakis Ioannis Alexandrou Andreas Othonos Received 9 June 2009 Accepted 18 August 2009 Published online to the authors 2009 Abstract Nowadays organic solar cells have the interest of engineers for manufacturing flexible and low cost devices. The considerable progress of this nanotechnology area presents the possibility of investigating new effects from a fundamental science point of view. In this letter we highlight the influence of the concentration of fullerene molecules on the ultrafast transport properties of charged electrons and polarons in P3HT PCBM blended materials which are crucial for the development of organic solar cells. Especially we report on the femtosecond dynamics of localized P2 at eV and delocalized DP2 at eV polaron states of P3HT matrix with the addition of fullerene molecules as well as the free-electron relaxation dynamics of PCBM-related states. Our study shows that as PCBM concentration increases the amplified exciton dissociation at bulk heterojunctions leads to increased polaron lifetimes. However the increase in PCBM concentration can be directly related to the localization of polarons creating thus two competing trends within the material. Our methodology shows that the effect of changes in structure and or composition can be monitored at the fundamental level toward optimization of device efficiency. E. Lioudakis El Energy Environment and Water Research Center The Cyprus Institute . Box 27456 1645 Nicosia Cyprus e-mail I. Alexandrou Electrical Engineering and Electronics University of Liverpool Liverpool L69 3GJ UK e-mail ioannis@ A. Othonos Research Center of Ultrafast Science Department of Physics University of Cyprus . Box 20537 1678 Nicosia Cyprus 3 September 2009