A multilayered approach to polyfluorene water-based organic photovoltaics

Solar Paint: From Synthesis to Printing

“…They showed that PFB:F8BT NPOPV devices with Al and Ca/Al cathodes exhibit qualitatively very similar behaviour, with a peak PCE of ~0.4% for Al (consistent with Stapleton's work [30]) and ~0.8% for Ca/Al, and that there is a distinct optimized thickness for the NP devices ( Figure 3). The optimal thickness is a consequence of the competing physical effects of the repair and filling of defects for thin films [32,33] and the development of stress cracking in thick films [34].…”

“…In 2012, Stapleton et al reported multilayered photovoltaic devices fabricated from PFB:F8BT nanoparticles, which demonstrated the highest power conversion efficiencies observed for these polyfluorene nanoparticle materials [30]. This increased performance was achieved through the control of the surface energies of the individual components in the polymer nanoparticle and the post-deposition processing of the polymer nanoparticle layers.…”

“…The optimal thickness is a consequence of the competing physical effects of the repair and filling of defects for thin films [32,33] and the development of stress cracking in thick films [34]. Indeed, Stapleton's work showed that the optimal layer thickness in these devices corresponds to the critical cracking thickness (CCT) above which stress cracking occurs, resulting in low shunt resistance and a reduction in device performance [30]. Overall, the work by Vaughan et al provided further confirmation that the intrinsic morphology of NPOPV PFB:F8BT devices enhances the exciton dissociation relative to the corresponding BHJ structure.…”

Fabrication conditions for efficient organic photovoltaic cells from aqueous dispersions of nanoparticles

“…Therefore, the overall power conversion efficiency (PCE) of OPVs fabricated from aqueous dispersions has been very low. [9][10][11]13,14 Different strategies used by various groups to improve PCEs -such as printing multiple layers of polymer ink, 14 and use of non-ionic uorosurfactants (FSO-100) 9 -have met with limited success. Herein, we report a strategy to address effectively the major impediments for OPV active layer fabrication from aqueous dispersions: surface de-wetting leading to surface roughness and non-uniform lms, and inefficient charge extraction.…”

Solution processable interface materials for nanoparticulate organic photovoltaic devices

“…The work function for aluminium is commonly reported to be 4.3 eV, 14 but for NPOPV devices, residual water in the active layer (which can be observed in the differential scanning calorimetry of the NPs 15 ) is likely to result in oxidation of the aluminium cathode and the formation of an interfacial oxide layer. The work function of a native layer of aluminium oxide on aluminium has been reported to be 3.8 eV; 16 however, for hydroxylated alumina interfaces, the work function rises to 4.3 eV.…”