摘要： The authors report an efficient organic photovoltaic device based on subphthalocyanine (SubPc):C 70 bulk heterojunction (BHJ) via the postannealing treatment. The power conversion efficiency is improved from 4.5% to 5.5% due to the increase in short-circuit current density ( J SC ) from 8.8 to 12.7 mA/cm 2 with the expense of decreased fill factor from 52% to 42%. From external quantum efficiency measurements, the spectral shape-independent enhancement over the entire spectrum suggests that the increased J SC mainly originates from improved charge collection efficiency. To confirm this inference, the hole and electron mobilities in the BHJ are estimated from the space-charge limited current, showing improved transport properties at the optimum temperature. Moreover, the morphologic change is also studied as a function of annealing temperature. A larger grain size is observed with increasing temperature due to the phase separation of SubPc and C 70 . However, at higher temperatures the strong aggregation of C 70 molecules may interrupt the pathway of SubPc, resulting in hindered charge transport and, hence, reduced J SC . 出版日期： 2013 出處： International journal of photoenergy, 2013, Vol.2013, p.1-7 資源來源： 華藝CEPS中文電子期刊服務 識別號： ISSN: 1110-662X 識別號： EISSN: 1687-529X 識別號： DOI: 10.1155/2013/585196
