用渡越时间法(TOF)分别测试了采用旋涂和滴涂方法制备的poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene](MEH-PPV)薄膜的空穴迁移率,用原子力显微镜对这两种方法制备的薄膜表面形貌进行了研究.结果表明使用滴涂法有利于聚合物形成有序薄膜结构,能有效提高空穴迁移率.用滴涂法制备的基于MEH-PPV:phenyl C61-butyric acid methyl ester(PCBM)共混薄膜的太阳电池,对比用旋涂法制备的太阳电池,其能量转换效率提高了35%.综合分析薄膜的吸收系数,表面形貌以及空穴迁移率等数据,可以确认滴涂法制备的聚合物薄膜具有更强的光吸收能力,改善了电子与空穴载流子传输的平衡性,使得太阳电池的性能有明显的改善和提高.这种利用滴涂法制备聚合物薄膜的技术对使用印刷方法制备薄膜太阳电池有一定的参考价值.
Hole mobility of poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenyleneviny lene] (MEH-PPV) film fabricated by spin-casting and drop-casting has been measured by time-of-flight (TOF) technique. The non-dispersive hole transport current waveform is obtained. The results exhibit that the hole mobility of MEH-PPV prepared by drop-casting is higher than that of the film prepared by spin-casting. The solar cells based on MEH-PPV and fullerene derivative blend films prepared by spin-casting and drop-casting,respectively,were fabricated. The power-conversion efficiency (PCE) of the drop-casting device has a great improvement of over 35%,compared with that of spin-casting one. The improvement is attributed to the stronger absorption and better balance of electron and hole transport in MEH-PPV polymer films.