High performance ternary solar cells based on P3HT:PCBM and ZnPc-hybrids

Single walled carbon nanotubes (SWCNTs) and reduced graphene oxide (rGO) covalently and non-covalently functionalised by zinc phthalocyanine (ZnPc) were added to P3HT:PCBM blend in order to investigate the effects of these hybrid materials on P3HT:PCBM organic solar cell performance. Adding a small amount of these hybrids to P3HT:PCBM blend does not significantly alter the absorption spectra of the latter nor its structure. ZnPc–rGO and ZnPc–SWCNT hybrid features have appeared on the P3HT:PCBM surface morphology as verified by SEM and AFM images. However these hybrid materials have caused significant effects on the electrical properties of the studied blends. An increase of about two orders of magnitudes has been observed in the electrical conductivity. Space charge limited conduction theory was employed to investigate the charge carriers' mobility whereas a thermionic emission model was used to evaluate the recombination rate based on an estimated diode ideality factor. Solar cell devices based on P3HT:PCBM:ZnPc–SWCNTs-co bonded have demonstrated best device performance with PCE of 5.3%, Jsc of 12.6 mA cm−2, Voc of 0.62 V and FF of 68%. A reference device based on bare P3HT:PCBM blend has exhibited PCE of just under 3.5%, Jsc of 9.3 mA cm−2, Voc of 0.62 V and FF of 60%

Conducting polymer functionalized multi-walled carbon nanotubes nanocomposites: Optical properties and morphological characteristics

International audienceDonor/acceptor heterostructures formed by a donor conducting polymer and carbon nanotubes as acceptor materials are elaborated. Carbon nanotubes (CNTs) have been functionalized with polystyrene. A huge potential for functionalized CNTs for an effective charge transfer was shown. Moreover, optical properties have been correlated with morphological characteristics. We conclude that there is a relationship between the morphology and the performances of polymer/CNTs bulk heterojunction nanocomposites, integrated as photoactive layer for photovoltaic application

Degree of phase separation effects on the charge transfer properties of P3HT:Graphene nanocomposites

Graphene layers were introduced into the matrix of regioregularpoly(3-hexylthiophene-2,5-diyl)(RR-P3HT) via solution processing in the perspective of the development of organic nanocomposites with high P3HT/Graphene interfaces areas for efficient charge transfer process. P3HT and graphene act as electrons donor and electrons acceptor materials,respectively. Spatial Fourier Transforms(FFT) and power spectral density(PSD) analysis of the AFM images show that the phase separation decreases with increasing the graphene weight ratio in the P3HTmatrix. The Raman spectra of the P3HT: Graphene nanocomposites shows that the G-band of graphene shifts to low frequencies with progressive addition of graphene which proves that there is an interaction between the nanowires of P3HT and the graphene layers. We suggest that the shift of the G-band is due to electrons transfer from P3HT to graphene. The quenching of the photoluminescence(PL) intensity of P3HT with addition of graphene proves also that an electrons transfer process occurred at the P3HT/Grapheneinterfaces

Charge transfer properties in P3HT:graphene capped InAs/GaAs QDs hybrid heterostructure for photovoltaic application

In this work we have developed hybrid organic/inorganic nanostructure based on InAs/GaAs quantum dots (QDs) capped with P3HT:graphene organic nanocomposite using spin-coating method. InAs/GaAs QDs are grown by molecular beam epitaxy on n+-GaAs (0 0 1) substrate. The morphological properties are studied through atomic force microscopy (AFM) and scanning tunneling microscopy (STM). Raman spectroscopy analyzes show that the encapsulation of the InAs/GaAs QDs by P3HT:graphene nanocomposite keeps unchanged the indium concentration in the quantum dots due to the negligible strain effect of the organic cap layer on the QDs compared with the conventional GaAs cap layer. The quenching of the photoluminescence (PL) intensity of P3HT proves that an electrons transfer process from P3HT to graphene and from P3HT to InAs/GaAs QDs has occurred. We show that the proposed P3HT:graphene cap layer could replace the conventional GaAs cap layer for the elaboration of optoelectronic devices

Effects of the graphene content on the conversion efficiency of P3HT: graphene based organic solar cells

We investigate the effects of the insertion of graphene in the matrix of regioregular poly (3-hexylthiophene-2,5-diyl) (RR-P3HT) on the conversion efficiency of ITO/P3HT:Graphene/Au solar cells. The X-ray diffraction (XRD) measurements show that progressive addition of graphene reduces the degree of order of P3HT lamellae along the hexyl-side direction (a-axis). The insertion of low graphene content in the P3HT matrix reduces the RMS roughness of the P3HT thin film, and improves the optical absorption properties of the device in the visible range. However for high doping level we observe the formation of graphene aggregates which in turn reduces the optical absorption properties of the device. The observed effects arising after addition of graphene to P3HT, and their relationship with the conversion efficiency of the devices are discussed in this work