酞菁铜/氟代苯基苝酰亚胺复合材料的聚集态结构及光伏性能

利用真空共沉积法将一种新型半导体材料2,4-二氟代苯基苝酰亚胺(D24DFPP)和传统的有机p型材料酞菁铜(CuPc)复合, 并制成结构为ITO/CuPc/Composite Layer/D24DFPP/Al的光伏器件, 测试表明, 这种含有两种半导体分子复合结构的光伏器件的效率比传统双层器件要高, 并且随复合层中两种材料比例的不同表现出一定的趋势. UV-Vis, XRD和AFM等表征手段证明, 这一现象可以用不同复合比下复合层聚集态结构的不同来解释: 两种有机半导体分子在复合后形成微相分离的结构, 当两种分子含量接近时, 相分离微区最小, 给受体分子接触面积最大, 因而电荷分离效率最高；当其中一种分子含量占优时, 相团聚和相分离倾向增大, 电荷分离效率降低, 因而光伏转换效率下降. 此外, 复合层厚度对转换效率也有一定程度的影响, 当光吸收和载流子扩散因素达到最佳平衡时, 光伏性能得到最优化.

Aggregate Structure and Photovoltaic Property of CuPc/D24DFPP Co-deposition Composite Material

A new kind of n-type material N,N'-di-(2,4-difluorophenyl)-3,4,9,10-perylenetetracarboxylic diimide (D24DFPP) was co-deposited in vacuum with p-type copper phthalocyanine (CuPc) to obtain the composite material. Using this composite material, a photovoltaic (PV) device with the structure of ITO/CuPc/composite layer/D24DFPP/Al was made. A higher energy conversion efficiency (ECE) was ob- tained when compared with a traditional two layered PV device, and a certain tendency changed with varied relative proportions of the two materials. Through UV-Vis, XRD and AFM characterizations, it was found that the changes could be ascribed to the aggregate structure of the composite layer: the two semiconductors formed a structure of micro-phase separation after co-deposition. When the contents of the two molecules were almost equal, the size of the micro-zones formed by phase separation reached the minimum, resulting in a larger donor-accepter contact area and thus a higher charge separation efficiency; if the content was dominated by one component, conglomeration and phase separation increased, giving a lower charge separa- tion efficiency and ECE. Further more, it was disclosed that the thickness of the composite layer also had an influence on ECE which would be optimized only if the factors of the light absorbance and the charge carrier diffusion came to a balance.