Effect of the Active Layer Thickness on the Device Performance of Polymer Solar Cells Having [60]PCBM and [70]PCBM as Electron Acceptor

Abstract Recently it has been shown that the use of [70]PCBM as electron acceptor in polymer solar cells can improve the current output of such devices because C70 derivatives have a stronger and broader absorption compared to C60 ones. In this work we studied the influence of the fullerene on the optical behaviour of the photoactive blend film of a polymer solar cell. We simulated the optical absorption of the active layer inside the device structure and we calculated the maximum achievable short circuit current density with the aim to correlate the variation of the optical constants to the output current of the device. Afterward, we realized several polymer solar cells and we proved the theoretical findings

ITO-free Anode with Plasmonic Silver Nanoparticles for High Efficient Polymer Solar Cells

Abstract In this work we improved the performance of ITO-free polymer solar cells (PSCs) by incorporating silver nanoparticles (AgNPs) in the highly conductive (HC) PEDOT:PSS anode. The AgNPs were synthetized in-situ in the PEDOT:PSS water dispersion. This anode was used to realize PSCs with the following geometry: glass/HC-PEDOT:PSS/PEDOT:PSS/PBDTTT-C:[70]PCBM/Ca/Al. All the devices were characterized by UV-VIS spectroscopy, impedance spectroscopy, IV light, IV dark and quantum efficiency measurements. The presence of AgNPs in the HC-PEDOT:PSS anode contributes to improve the absorption of the photoactive layer and to lower the resistivity of the anode

Selective inclusion of chromophore molecules into poly(styrene-b-methylmethacrylate) block copolymer nanodomains: a study of morphological, optical and electrical properties

Innovative nanocomposites based on a nanostructured block copolymer (BCP) matrix whose lamellar nanodomains are selectively loaded with organic molecules, were prepared. A symmetric poly(styrene-b-methylmethacrylate) (PS-b-PMMA) amorphous BCP showing a lamellar morphology was employed. Thin films of PS-b-PMMA were deposited by spin-coating on indium thin oxide (ITO) substrate in order to achieve orientation of lamellae with the lamellar surface perpendicular to the substrate. Nanocomposites were then prepared by selective incorporation of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) molecules into the PS lamellar domain. The self-assembly of the BCP generated the nanotemplate to selectively control the spatial location of the PCBM molecules, in which the apolar properties of PS block provided the physical stabilization for achieving uniform PCBM distribution. These innovative approaches can be utilized as a tool to realize memory devices

Confinement of Semiconductor ZnO Nanoparticles in Block Copolymer Nanostructure

The morphology and the electrical properties of hybrid nanocomposites characterized by the dispersion of ZnO nanoparticles (NPs), a n-type semiconductor, within an organic nanostructured matrix of polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) block copolymer are presented. A selective inclusion of NPs only into the lamellar PS nanodomains of the block copolymer matrix has been achieved by synthetizing ZnO NPs coated with n-hexadecylamine (HDA) and tert-butylphosphonic acid (TBPA) molecules and subsequent thermal annealing of the nanocomposites ZnO NPs/PS-b-PMMA. Thermal treatments have allowed obtaining in one step the vertical orientation of the lamellar BCP nanodomains and the migration of the NPs to the PS domains, resulting in the formation of nanocomposites characterized by a precise control of the position of n-semiconductor ZnO NPs. Current-voltage measurements on the nanocomposites have indicated the presence of continuous path of charge carriers in the BCP films when the ZnO NPs content is above a threshold concentration. The experimental results have allowed the setup and validation of a theoretical protocol to study heterogeneous interfaces. In particular, the interaction of ZnO most stable nonpolar surface with prototypical capping agents has been analyzed by using density functional theory (DFT) calculations

Interlaboratory indoor ageing of roll-to-roll and spin coated organic photovoltaic devices: Testing the ISOS tests

The inter-comparability of the stability measurements of organic photovoltaic (OPV) technologies in dark is addressed. Four primary factors that affect the reproducibility of the ageing rate determination and inter-comparison are discussed: production/encapsulation of the samples, current-voltage (IV) characterization, testing conditions for ageing and lifetime determination from a decay curve. Results of inter-laboratory ageing studies of roll-to-roll and spin coated samples with correspondingly flexible plastic packaging and glass encapsulation tested under dark test conditions among 7 laboratories are presented. ISOS test conditions, proposed recently as guiding protocols for testing OPV stability, are applied in the study. The reproducibility of the performance versus the production and encapsulation techniques is firstly studied. The results reveal a significant improvement in the reproducibility when going from manual spin coating to roll-to-roll production. Furthermore, the reproducibility of current-voltage (IV) measurement and preconditioning (light soaking treatments) are addressed. Additionally, the inter-comparison of the degradation rates of the samples tested under three different dark test conditions (ambient, dry/heat, damp heat) reported by different groups are analyzed revealing a reasonable agreement on the degradation rates of the stability curves for each test condition. Finally, a logarithmic diagram for OPV lifetime associated with common time units is proposed that allows conveniently categorizing and intercomparing the stability performance of different samples tested under different test conditions.JRC.F.7-Renewables and Energy Efficienc