Najafov Hikmat, Biaggio Ivan, Podzorov Vitaly, Calhoun Matthew F, Gershenson Michael E
Department of Physics and Center for Optical Technologies, Lehigh University, Bethlehem, Pennsylvania 18015, USA.
Phys Rev Lett. 2006 Feb 10;96(5):056604. doi: 10.1103/PhysRevLett.96.056604. Epub 2006 Feb 9.
By simultaneously measuring the excitation spectra of transient luminescence and transient photoconductivity after picosecond pulsed excitation in rubrene single crystals, we show that free excitons are photoexcited starting at photon energies above 2.0 eV. We observe a competition between photoexcitation of free excitons and photoexcitation into vibronic states that subsequently decays into free carriers, while molecular excitons are instead formed predominantly through the free exciton. At photon energies below 2.25 eV, free charge carriers are created only through a long-lived intermediate state with a lifetime of up to 0.1 ms and no free carriers appear during the exciton lifetime.
通过同时测量红荧烯单晶在皮秒脉冲激发后的瞬态发光和瞬态光电导的激发光谱，我们发现自由激子在光子能量高于2.0 eV时开始被光激发。我们观察到自由激子的光激发与光激发进入随后衰变为自由载流子的振动态之间存在竞争，而分子激子主要通过自由激子形成。在光子能量低于2.25 eV时，自由电荷载流子仅通过寿命长达0.1 ms的长寿命中间态产生，并且在激子寿命期间没有自由载流子出现。
