Morse Graham E, Gantz Jeremy L, Steirer K Xerxes, Armstrong Neal R, Bender Timothy P
Department of Chemical Engineering & Applied Chemistry, University of Toronto , Toronto, Ontario M5S 3E5, Canada.
ACS Appl Mater Interfaces. 2014 Feb 12;6(3):1515-24. doi: 10.1021/am404179z. Epub 2014 Jan 22.
We have demonstrated that pentafluoro phenoxy boron subphthalocyanine (F5BsubPc) can function as either an electron donor or an electron acceptor layer in a planar heterojunction organic photovolatic (PHJ OPV) cell. F5BsubPc was incorporated into devices with the configurations ITO/MoO3/F5BsubPc/C60/BCP/Al (F5BsubPc used as an electron-donor/hole-transport layer) and ITO/MoO3/Cl-BsubPc/F5BsubPc/BCP/Al (F5BsubPc used as an electron-acceptor/electron-transport layer). Each unoptimized device displayed open-circuit photopotentials (Voc) close to or in excess of 1 V and respectrable power conversion efficiencies. Ultraviolet photoelectron spectroscopy (UPS) was used to characterize the band-edge offset energies at the donor/acceptor junctions. HOMO and LUMO energy level offsets for the F5BsubPc/C60 heterojunction were determined to be ca. 0.6 eV and ca. 0.7 eV, respectively. Such offsets are clearly large enough to produce rectifying J/V responses, efficient exciton dissociation, and photocurrent production at the interface. For the Cl-BsubPc/F5BsubPc heterojunction, the estimated offset energies were found to be ca. 0.1 eV. However, reasonable photovoltaic activity was observed, with photocurrent production coming from both BsubPc species layers. Incident and absorbed photon power conversion efficiencies (IPCE and APCE) showed that photocurrent production qualitatively tracked the absorbance spectra of the donor/acceptor heterojunctions, with some additional photocurrent activity on the low energy side of the absorbance band. We suggest that photocurrent production at higher wavelengths may be a result of charge-transfer species at the donor/acceptor interface. Cascade photovoltaics were also fabricated to expand on the understanding of the role of F5BsubPc in such device architectures.
我们已经证明，五氟苯氧基硼亚酞菁（F5BsubPc）在平面异质结有机光伏（PHJ OPV）电池中既可以作为电子供体层，也可以作为电子受体层。F5BsubPc被应用于具有ITO/MoO3/F5BsubPc/C60/BCP/Al结构的器件中（F5BsubPc用作电子供体/空穴传输层）以及ITO/MoO3/Cl-BsubPc/F5BsubPc/BCP/Al结构的器件中（F5BsubPc用作电子受体/电子传输层）。每个未优化的器件都显示出接近或超过1 V的开路光电压（Voc）以及可观的功率转换效率。紫外光电子能谱（UPS）被用于表征供体/受体结处的带边偏移能量。F5BsubPc/C60异质结的HOMO和LUMO能级偏移分别被确定为约0.6 eV和约0.7 eV。这样的偏移显然足够大，能够在界面处产生整流J/V响应、高效的激子解离和光电流产生。对于Cl-BsubPc/F5BsubPc异质结，估计的偏移能量约为0.1 eV。然而，观察到了合理的光伏活性，光电流产生来自于两种BsubPc物种层。入射和吸收光子功率转换效率（IPCE和APCE）表明，光电流产生定性地跟踪了供体/受体异质结的吸收光谱，在吸收带的低能量侧还有一些额外的光电流活性。我们认为，较高波长处的光电流产生可能是供体/受体界面处电荷转移物种所致。还制备了级联光伏器件，以进一步了解F5BsubPc在此类器件结构中的作用。
