Performance improvement of MEH-PPV:PCBM solar cells using bathocuproine and bathophenanthroline as the buffer layers  

作　　者：刘晓东 赵谡玲 徐征 张福俊 张天慧 龚伟 闫光 孔超 王永生 徐叙瑢 

机构地区：[1]Key Laboratory of Luminescence and Optical Information of Ministry of Education, Beijing Jiaotong University

出　　处：《Chinese Physics B》2011年第6期540-545,共6页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China (Grant Nos. 60978060, 10804006, and 10974013);the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20090009110027);the Research Fund for the Youth Scholars of the Doctoral Program of Higher Education, China (Grant No. 20070004031);the Beijing Municipal Natural Science Foundation of China (Grant No. 1102028);the Beijing Municipal Science & Technology Commission of China (Grant No. Z090803044009001);the National Basic Research Program of China (Grant No. 2010CB327705);the International Science and Technology Cooperation Program (Grant No. 2008DFA61420)

摘　　要：In this work, bathocuproine （BCP） and bathophenanthroline （Bphen）, commonly used in small-molecule organic solar cells （OSCs）, are adopted as the buffer layers to improve the performance of the polymer solar cells （PSCs） based on poly（2-methoxy-5-（2-ethylhexyloxy）-1,4-phenylenevinylene） （MEH-PPV）： [6,6]-phenyl-C61-butyric acid methyl ester （PCBM） bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-am BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen （i） increasing the optical field, and hence the absorption in the active layer, （ii） effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum （Al） interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance （Rs）, and （iii） preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode.In this work, bathocuproine （BCP） and bathophenanthroline （Bphen）, commonly used in small-molecule organic solar cells （OSCs）, are adopted as the buffer layers to improve the performance of the polymer solar cells （PSCs） based on poly（2-methoxy-5-（2-ethylhexyloxy）-1,4-phenylenevinylene） （MEH-PPV）： [6,6]-phenyl-C61-butyric acid methyl ester （PCBM） bulk heterojunction. By inserting BCP or Bphen between the active layer and the top cathode, all the performance parameters are dramatically improved. The power conversion efficiency is increased by about 70% and 120% with 5-am BCP and 12-nm Bphen layers, respectively, when compared with that of the devices without any buffer layer. The performance enhancement is attributed to BCP or Bphen （i） increasing the optical field, and hence the absorption in the active layer, （ii） effectively blocking the excitons generated in MEH-PPV from quenching at organic/aluminum （Al） interface due to the large band-gap of BCP or Bphen, which results in a significant reduction in series resistance （Rs）, and （iii） preventing damage to the active layer during the metal deposition. Compared with the traditional device using LiF as the buffer layer, the BCP-based devices show a comparable efficiency, while the Bphen-based devices show a much larger efficiency. This is due to the higher electron mobility in Bphen than that in BCP, which facilitates the electron transport and extraction through the buffer layer to the cathode.

关 键 词：polymer solar cells BATHOCUPROINE bathophenanthroline buffer layer 

分 类 号：TM914.4[电气工程—电力电子与电力传动] TN304.23[电子电信—物理电子学]