电化学合成聚噻吩薄膜提高光伏电池的开路电压

Enhanced V_(oc) in Photovoltaic Cell by Electrodeposited Polythiophene Thin Film

以铟锡氧化物(ITO)/聚(3,4-亚乙二氧基噻吩)-聚(苯乙烯磺酸)(PEDOT:PSS)为工作电极,采用电化学沉积法,直接在其上形成聚3-己基噻吩(P3HT)薄膜。其紫外可见吸收光谱的峰值约位于410nm处,吸收边延至610nm处,禁带宽度为2.04eV。测得其最高占有分子轨道(HOMO)能级为-5.21eV,而化学合成P3HT的HOMO能级为-5.02eV,这可能源于电化学合成聚噻吩的规整度比化学合成的要高。原子力显微镜AFM形貌结果表明电化学合成的P3HT中噻吩分子排列紧密,循环伏安扫描表明此P3HT薄膜的电化学性质稳定。采用该电化学合成的聚噻吩与富勒烯衍生物[6,6]-苯基-C61-丁酸甲酯(PCBM)复合而成的光伏电池的开路电压高达0.76V,这主要源于电化学合成聚噻吩HOMO能级的降低,因而揭示了提高光伏电池开路电压的新途径。

Poly（3-hexylthiophene）（P3HT） thin films were electrochemically deposited directly on indium tin oxide（ITO）/poly（3,4-ethylenedioxythiophene）-poly（styrenesulfonate）（PEDOT：PSS） substrates.Its optical absorption peak is located at about 410 nm and tailing to 610 nm,corresponding to 2.04 eV of bandgap.Its highest occupied molecular orbital（HOMO） energy is-5.21 eV,while the HOMO energy of the chemically synthesized P3HT is-5.02 eV.The lower HOMO energy of the electrodeposited P3HT may be attributed to the enhancement of regularity.The morphology of the P3HT thin film characterized by atomic force microscopy（AFM） indicates that the molecules contact firmly.The cyclic voltammetry results show that its electrochemical property is stable.theauthors prepared photovoltaic cell with the P3HT and [6,6]-phenyl-C61-butyric acid methyl ester（PCBM） as the active layer.Because of the lower HOMO of the electrodeposited P3HT,the open circuit voltage（Voc） of the device is up to 0.76 V,indicating a new way to enhance the Voc of the organic photovoltaic cells.