Partner: Massimiliano Lanzi

University of Bologna (IT)

Recent publications
1.Pierini F., Lanzi M., Nakielski P., Pawłowska S., Urbanek O., Zembrzycki K., Kowalewski T.A., Single-Material Organic Solar Cells Based on Electrospun Fullerene-Grafted Polythiophene Nanofibers, Macromolecules, ISSN: 0024-9297, DOI: 10.1021/acs.macromol.7b00857, Vol.50, No.13, pp.4972-4981, 2017
Abstract:

Highly efficient single-material organic solar cells (SMOCs) based on fullerene-grafted polythiophenes were fabricated by incorporating electrospun one-dimensional (1D) nanostructures obtained from polymer chain stretching. Poly(3-alkylthiophene) chains were chemically tailored in order to reduce the side effects of charge recombination which severely affected SMOC photovoltaic performance. This enabled us to synthesize a donor–acceptor conjugated copolymer with high solubility, molecular weight, regioregularity, and fullerene content. We investigated the correlations among the active layer hierarchical structure given by the inclusion of electrospun nanofibers and the solar cell photovoltaic properties. The results indicated that SMOC efficiency can be strongly increased by optimizing the supramolecular and nanoscale structure of the active layer, while achieving the highest reported efficiency value (PCE = 5.58%). The enhanced performance may be attributed to well-packed and properly oriented polymer chains. Overall, our work demonstrates that the active material structure optimization obtained by including electrospun nanofibers plays a pivotal role in the development of efficient SMOCs and suggests an interesting perspective for the improvement of copolymer-based photovoltaic device performance using an alternative pathway.

Affiliations:
Pierini F.-IPPT PAN
Lanzi M.-University of Bologna (IT)
Nakielski P.-IPPT PAN
Pawłowska S.-IPPT PAN
Urbanek O.-IPPT PAN
Zembrzycki K.-IPPT PAN
Kowalewski T.A.-IPPT PAN
2.Lanzi M., Salatelli E., Giorgini L., Mucci A., Pierini F., Di-Nicola F.P., Water-soluble polythiophenes as efficient charge-transport layers for the improvement of photovoltaic performance in bulk heterojunction polymeric solar cells, EUROPEAN POLYMER JOURNAL, ISSN: 0014-3057, DOI: 10.1016/j.eurpolymj.2017.10.032, Vol.97, pp.378-388, 2017
Abstract:

Water-soluble regioregular poly{3-[(6-sodium sulfonate)hexyl]thiophene} (PT6S) and poly{3-[(6-trimethylammoniumbromide)hexyl]thiophene} (PT6N) have been synthesized and employed both as photoactive layers for the assembling of “green” bulk-heterojunction organic solar cells and as charge-collection layers in a cell with “classic” architecture. While the photovoltaic performances obtained with the two aforementioned polymers were lower than the reference cell, their latter use allowed to notably increase the inherent J-V properties, leading to a considerable enhancement in the overall photovoltaic output. The power conversion efficiency of the optimized multilayer BHJ solar cell reached 4.78%, revealing a higher efficiency than the reference cell (3.63%).

Keywords:

Water-soluble polymer, Polythiophene derivative, Bulk heterojunction, Organic photovoltaic, Interfacial layer

Affiliations:
Lanzi M.-University of Bologna (IT)
Salatelli E.-University of Bologna (IT)
Giorgini L.-University of Bologna (IT)
Mucci A.-University of Modena (IT)
Pierini F.-IPPT PAN
Di-Nicola F.P.-University of Bologna (IT)
3.Pierini F., Lanzi M., Nakielski P., Kowalewski T.A., Electrospun Polyaniline-Based Composite Nanofibers: Tuning the Electrical Conductivity by Tailoring the Structure of Thiol-Protected Metal Nanoparticles, Journal of Nanomaterials, ISSN: 1687-4110, DOI: 10.1155/2017/6142140, Vol.2017, pp.1-10, 2017
Abstract:

Composite nanofibers made of a polyaniline-based polymer blend and different thiol-capped metal nanoparticles were prepared using ex situ synthesis and electrospinning technique. The effects of the nanoparticle composition and chemical structure on the electrical properties of the nanocomposites were investigated. This study confirmed that Brust’s procedure is an effective method for the synthesis of sub-10 nm silver, gold, and silver-gold alloy nanoparticles protected with different types of thiols. Electron microscopy results demonstrated that electrospinning is a valuable technique for the production of composite nanofibers with similar morphology and revealed that nanofillers are well-dispersed into the polymer matrix. X-ray diffraction tests proved the lack of a significant influence of the nanoparticle chemical structure on the polyaniline chain arrangement. However, the introduction of conductive nanofillers in the polymer matrix influences the charge transport noticeably improving electrical conductivity. The enhancement of electrical properties is mediated by the nanoparticle capping layer structure. The metal nanoparticle core composition is a key parameter, which exerted a significant influence on the conductivity of the nanocomposites. These results prove that the proposed method can be used to tune the electrical properties of nanocomposites.

Affiliations:
Pierini F.-IPPT PAN
Lanzi M.-University of Bologna (IT)
Nakielski P.-IPPT PAN
Kowalewski T.A.-IPPT PAN
4.Lanzi M., Salatelli E., Di-Nicola F.P., Zuppiroli L., Pierini F., A new photocrosslinkable oligothiophene for organic solar cells with enhanced stability, MATERIALS CHEMISTRY AND PHYSICS, ISSN: 0254-0584, DOI: 10.1016/j.matchemphys.2016.10.034, Vol.186, pp.98-107, 2017
Abstract:

A novel thiophenic tetramer containing a cinnamate group in the side chain with a functionalization degree of 50% is reported. The tetramer was obtained by means of a simple and straightforward procedure involving the functionalization of a p-methoxyphenoxy substituted thiophenic precursor, which led to a soluble product with a good yield. The oligomer was fully characterized from a structural and chemical point of view and employed for the fabrication of small molecule organic solar cells exploiting the bulk heterojunction (BHJ) architecture. The presence of an UV-light sensitive group in the tetramer allowed the photocrosslinking of tetramer/PCBM blends, giving high values of photocurrent and conversion efficiency for the exposed samples. Moreover, the UV-treated devices showed improved stability, even upon heating for three days at 130 °C, thus confirming that photocrosslinking can strongly reduce phase segregation under severe operational conditions.

Keywords:

Electronic materials, Polymers, Fullerenes, Nanostructures, Electrical characterization, Semiconductors

Affiliations:
Lanzi M.-University of Bologna (IT)
Salatelli E.-University of Bologna (IT)
Di-Nicola F.P.-University of Bologna (IT)
Zuppiroli L.-University of Bologna (IT)
Pierini F.-IPPT PAN
5.Pierini F., Lanzi M., Nakielski P., Pawłowska S., Zembrzycki K., Kowalewski T.A., Electrospun poly(3-hexylthiophene)/poly(ethylene oxide)/graphene oxide composite nanofibers: effects of graphene oxide reduction, Polymers for Advanced Technologies, ISSN: 1042-7147, DOI: 10.1002/pat.3816, Vol.27, No.11, pp.1465-1475, 2016
Abstract:

In this article, we report on the production by electrospinning of P3HT/PEO, P3HT/PEO/GO, and P3HT/PEO/rGO nanofibers in which the filler is homogeneously dispersed and parallel oriented along the fibers axis. The effect of nanofillers' presence inside nanofibers and GO reduction was studied, in order to reveal the influence of the new hierarchical structure on the electrical conductivity and mechanical properties. An in-depth characterization of the purity and regioregularity of the starting P3HT as well as the morphology and chemical structure of GO and rGO was carried out. The morphology of the electrospun nanofibers was examined by both scanning and transmission electron microscopy. The fibrous nanocomposites are also characterized by differential scanning calorimetry to investigate their chemical structure and polymer chains arrangements. Finally, the electrical conductivity of the electrospun fibers and the elastic modulus of the single fibers are evaluated using a four-point probe method and atomic force microscopy nanoindentation, respectively. The electrospun materials crystallinity as well as the elastic modulus increase with the addition of the nanofillers while the electrical conductivity is positively influenced by the GO reduction.

Keywords:

electrospun composite nanofibers, poly(3-hexylthiophene), graphene oxide, electrical conductivity, mechanical properties

Affiliations:
Pierini F.-IPPT PAN
Lanzi M.-University of Bologna (IT)
Nakielski P.-IPPT PAN
Pawłowska S.-IPPT PAN
Zembrzycki K.-IPPT PAN
Kowalewski T.A.-IPPT PAN
6.Pierini F., Lanzi M., Lesci I.G., Roveri N., Comparison between Inorganic Geomimetic Chrysotile and Multiwalled Carbon Nanotubes in the Preparation of One-dimensional Conducting Polymer Nanocomposites, Fibers and Polymers, ISSN: 1229-9197, DOI: 10.1007/s12221-015-0426-x, Vol.16, No.2, pp.426-433, 2015
Abstract:

The aim of this study was to examine the role of the nanofillers spatial arrangement in the electrical properties of hybrid organic-inorganic fibers. In this paper, we have presented experimental results for preparation of fibers with a nanometric diameter based on a polyaniline/poly(ethylene oxide) doped blend and geomimetic chrysotile nanotubes. The nanostructured material was prepared using electrospinning techniques. Electrospun fibers made by pristine polymers and by the same blend loaded with carbon nanotubes were used as reference materials to compare the structural, and electrical properties of the novel organic-inorganic material. Generally, electrical properties were improved by the addition of materials that have high conductivity. Electrospun fibers filled with a traditional insulator like chrysotile have shown higher electrical conductivity than the pristine materials. In order to fully understand how structural variations impact upon the electrical conductivity the materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), differential scanning calorimetry (DSC) and four-point probe method. The results suggest that the occurred electrical conductivity gain could be attributed to parallel orientation of the chrysotile nanotubes and higher crystallinity induced by the one-dimensional nanostructured filler materials. The obtained results bring us one step closer to using intrinsically conducting polymers (ICPs) in the creation of functionalized polymeric nanocomposites for nanotechnology.

Keywords:

Nanocomposites, Conductive polymer, Electrospinning, Chrysotile, Carbon nanotubes

Affiliations:
Pierini F.-IPPT PAN
Lanzi M.-University of Bologna (IT)
Lesci I.G.-University of Bologna (IT)
Roveri N.-University of Bologna (IT)
7.Lanzi M., Paganin L., Pierini F., Errani F., Di-Nicola F.P., Use of poly(3-methylthio)thiophene blends for direct laser tracing and bulck heterojunction solar cells, REACTIVE AND FUNCTIONAL POLYMERS, ISSN: 1381-5148, DOI: 10.1016/j.reactfunctpolym.2014.07.007, Vol.83, pp.33-41, 2014
Abstract:

In this article we demonstrate the use of a blend made of two regioregular polythiophenic derivatives, namely poly(3-methylthio)thiophene and poly(3-hexyl)thiophene, to obtain conductive traces by the simple laser exposure of their thin films to a suitable laser source. The polymeric blend was also tested as a photoactive layer for BHJ solar cells, showing an improved surface morphology and a wider absorption spectrum, thus resulting in an enhanced photovoltaic performance. In the standard condition normally used for the cell preparation, we obtained a 3.16% power conversion efficiency. The device showed good reproducibility and stability over time.

Keywords:

Electrical conductivity, Laser tracing, Bulk heterojunction polymeric solar cells, Regioregular polyalkylthiophenes, Polymer blends

Affiliations:
Lanzi M.-University of Bologna (IT)
Paganin L.-University of Bologna (IT)
Pierini F.-other affiliation
Errani F.-University of Bologna (IT)
Di-Nicola F.P.-University of Bologna (IT)
8.Lanzi M., Di-Nicola F.P., Livi M., Paganin L., Cappelli F., Pierini F., Synthesis and characterization of conjugated polymers for the obtainment of conductive patterns through laser tracing, JOURNAL OF MATERIALS SCIENCE, ISSN: 0022-2461, DOI: 10.1007/s10853-013-7204-1, Vol.48, pp.3877-3893, 2013
Abstract:

This article describes the preparation of thin films of conjugated polymers which can enhance their specific electrical conductivity by several orders of magnitude by changing their state from insulating to conducting materials. The examined polymers, i.e., a polyacetylenic and a polythiophenic derivative, are functionalized with thioalkylic side chains and are soluble in common organic solvents from which they lead to thick homogeneous films. The films can be deposited on different substrates, either rigid or flexible, and can be easily exposed to laser radiation to make them conductive. The process is irreversible, and the final conductivity is stable over time, even in the presence of high temperatures (up to 180°C), moisture, and air. The high stability of treated samples, easy polymer synthesis and quick and inexpensive suitably tailored laser tracing procedure make these materials very promising for applications in organic electronics and in the development of new electronic circuitry.

Affiliations:
Lanzi M.-University of Bologna (IT)
Di-Nicola F.P.-University of Bologna (IT)
Livi M.-University of Bologna (IT)
Paganin L.-University of Bologna (IT)
Cappelli F.-Stem S.a.s. (IT)
Pierini F.-other affiliation