Charge transfer properties in PVK:PcH2:C343:C60/π-Si hybrid nanocomposites for photovoltaics

We have developed hybrid organic/inorganic heterojunction based on PVK:PcH2:C343:C60 nanocomposite spin coated on porous silicon (π-Si) substrate, to investigate the efficiency of the combination of these materials as donor-acceptor (D/A) systems for photovoltaic applications. PcH2 and C343 organic dyes were incorporated into the matrix of PVK to enhance its optical absorption properties. The absorption spectrum of PVK was extended to the visible range, but the photoluminescence (PL) intensity was significantly increased. To reduce the dyes sensitization effect, especially the increase of the PL intensity, we have added molecules of buckminsterfullerenes (C60) to the PVK:PcH2:C343 ternary blend. Progressive addition of C60 decreases the PL intensity of the ternary blend. The quenching efficiency study proves that the nanocomposites of PVK:PcH2:C343:C60 reveal high PL quenching degree: ηc = 90.3%. The optimized concentration ratio of C60 was used to elaborate hybrid composites based on PVK:PcH2:C343:C60 coated on Si and π-Si substrates. The PL intensity of the ternary blend was more attenuated using π-Si than Si. This effect is due to the high specific area of π-Si which improves the excitons dissociation at the ternary blend/Si nanocrystallites interfaces.