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制备了一系列不同浓度的PCBM掺杂型聚合物发光二极管,结构为ITO/PEDOT:PSS/SY-PPV:PCBM(x wt%)/Ca/Al,并在室温下测量了器件的电流随外加磁场的变化(即磁电导效应)曲线,以研究电子-空穴对(e-h pair)解离率对有机磁电导效应的调控作用.实验发现:未掺杂PCBM的器件,其磁电导曲线表现为随磁场的增加先迅速增大,而后趋于饱和;而3wt%PCBM掺杂器件,其磁电导随磁场的增加先快速小幅增加,而后缓慢增大并且不趋于饱和;另外,两种器件的磁电导曲线的半峰宽明显不同(即趋于饱和的快慢明显不同),且3 wt%PCBM掺杂器件的磁效应值远小于未掺杂器件的磁效应值.分析了不同掺杂浓度器件中电子-空穴对解离率的变化规律,并用非洛伦兹经验公式对上述曲线进行拟合,认为PCBM掺杂器件的e-h pair解离率增大而导致这些e-h pair的寿命变短,寿命变短后的e-h pair来不及发生自旋混合进而使得磁电导曲线表现出慢饱和趋势.
A series of PCBM doped polymer light-emitting diodes with different concentrations of ITO / PEDOT: PSS / SY-PPV: PCBM (x wt%) / Ca / Al were prepared and measured at room temperature (Ie, magneto-conductance effect) curves to study the regulation of the eh pair dissociation rate on the organic magneto-conductance effect.It was found that the magneto-conductance curves of the undoped PCBM devices were With the increase of the magnetic field, it increases rapidly and then tends to be saturated. However, the magnetic conductivity of 3wt% PCBM-doped devices increases rapidly and slightly at first, then slowly increases and does not tend to be saturated. In addition, The half-width of the magneto-conductive curve is significantly different (ie, the speed of saturation tends to be significantly different), and the magnetic effect of the 3 wt% PCBM doped device is much smaller than that of the undoped device. Electron-hole pair dissociation rate of the law and non-Lorentz empirical formula to fit the curve, that the PCBM-doped device eh pair dissociation rate increases lead to the life of these eh pair shorter, After the shortened life expectancy, the eh pair is too late for spin mixing to make the magneto-conductance The curve shows a slow saturation trend.