Enhancing P3HT/TiO2 Hybrid Photovoltaic Performance by Incorporating High Surface Potential Silica Nanodots into Hole Transport Layer

We offer a novel approach to improve the performance of P3HT/TiO2 hybrid photovoltaic devices by incorporating either hydroxyl- or amino-functionalized silica nanodots (SND–OH or SND–NH2) into the hole transport layer of the PEDOT:PSS. The SNDs serve as screens between conducting polymer and ionomer PSS to improve the phase separation and charge transport of the PEDOT:PSS hole transport layer. The power conversion efficiency (PCE) was thus improved by 1.45 and 2.61 fold for devices fabricated with PEDOT:PSS containing 1 wt % of SND–OH (SND–OH device) and 1 wt % of SND–NH2 (SND–NH2 device), respectively, when compared with the devices fabricated by neat PEDOT:PSS. The increase in PCE arises from an increase in short circuit currents, which are affected by the phase separation of PEDOT:PSS with possessing incorporated SNDs. The low surface potential of hydroxyl-functionalized SNDs (SND–OH) is easily aggregated in the PEDOT:PSS solution and forms large-sized phase separation in the PEDOT:PSS film. The aggreg...