Search results for " heterojunction"
showing 10 items of 43 documents
Enhanced efficiency in plastic planar heterojunction solar cells by AuNPs positioned at donor-acceptor interfaces
2018
A new class of copolymers containing oligothiophene moieties with different length and fullerene units have been designed and prepared by an easy and inexpensive one-step synthetic approach. The incorporation of small quantities of these copolymers into bulk heterojunction (BHJ) solar cells with donor regioregular polythiophene (P3HT) and acceptor fullerene derivate (PCBM) results in a good control of the phase separation process without further affecting the BHJ optoelectronic properties. Indeed, these copolymers allow modulating under thermal annealing the growth of domains whose size depends on the length of the copolymer repetitive units. Domain size on the same length scale of the P3HT…
Bias and humidity effects on the ammonia sensing of perylene derivative/lutetium bisphthalocyanine MSDI heterojunctions
2016
International audience; In this paper, we prepared and studied sensors based on Molecular Semiconductor-Doped Insulator (MSDI) heterojunctions. These original devices are built with two stacked layers of molecular materials and exhibit very specific electrical and sensing properties. We studied the properties of a MSDI composed of the perylenetetracarboxylic dianhydride, PTCDA, or the fluorinated perylenebisimine derivative, C4F7-PTCDI, as n-type molecular material sublayers, and LuPc2 as a p-type semiconductor top layer. Their response to ammonia was compared to that of a resistor formed of only the top layer of the MSDI (LuPc2). Ammonia increases the current in the MSDIs whereas it causes…
Thiophene pyrenyl derivatives for the supramolecular processability of single-walled carbon nanotubes in thin film heterojunction
2017
Abstract A major problem for the use of single-wall carbon nanotubes (SWCNTs) in electronic devices relates to their poor processability. Chemical modification inevitably introduces defects in the nanotube lattice, resulting in a loss of electronic properties. In this contest, we report on a supramolecular approach with the aim of increasing the dispersion of SWCNTs in solution and in organic semiconductor matrices by ensuring the optoelectronic properties. In particular, new pyrenyl derivatives of thiophene have been synthesized and used to improve the solubility of SWCNTs for electron transfer in thin film heterojunction with poly(3-hexylthiophene) (P3HT) as donor system. Photoinduced ele…
Sub-gap defect density characterization of molybdenum oxide: An annealing study for solar cell applications
2020
AbstractThe application of molybdenum oxide in the photovoltaic field is gaining traction as this material can be deployed in doping-free heterojunction solar cells in the role of hole selective contact. For modeling-based optimization of such contact, knowledge of the molybdenum oxide defect density of states (DOS) is crucial. In this paper, we report a method to extract the defect density through nondestructive optical measures, including the contribution given by small polaron optical transitions. The presence of defects related to oxygen-vacancy and of polaron is supported by the results of our opto-electrical characterizations along with the evaluation of previous observations. As part…
Progress in Violet Light-Emitting Diodes Based on ZnO/GaN Heterojunction
2020
Progress in light-emitting diodes (LEDs) based on ZnO/GaN heterojunctions has run into several obstacles during the last twenty years. While both the energy bandgap and lattice parameter of the two semiconductors are favorable to the development of such devices, other features related to the electrical and structural properties of the GaN layer prevent an efficient radiative recombination. This work illustrates some advances made on ZnO/GaN-based LEDs, by using high-thickness GaN layers for the p-region of the device and an ad hoc device topology. Heterojunction LEDs consist of a quasicoalesced non-intentionally doped ZnO nanorod layer deposited by chemical bath deposition onto a metal&ndash
Enhanced Solar Light Photocatalytic Activity of Ag Doped TiO2–Ag3PO4 Composites
2020
Composites comprised of Ag3PO4 and bare TiO2 (TiO2@Ag3PO4) or silver doped TiO2 (Ag@TiO2&ndash
Organic Heterojunction Devices Based on Phthalocyanines: A New Approach to Gas Chemosensing.
2020
Organic heterostructures have emerged as highly promising transducers to realize high performance gas sensors. The key reason for such a huge interest in these devices is the associated organic heterojunction effect in which opposite free charges are accumulated at the interface making it highly conducting, which can be exploited in producing highly sensitive and faster response kinetics gas sensors. Metal phthalocyanines (MPc) have been extensively studied to fabricate organic heterostructures because of the large possibilities of structural engineering which are correlated with their bulk thin film properties. Accordingly, in this review, we have performed a comprehensive literature surve…
Porphyrins and BODIPY as Building Blocks for Efficient Donor Materials in Bulk Heterojunction Solar Cells
2017
International audience; Advances in the synthesis and application of highly efficient polymers and small molecules over the last two decades have enabled the rapid advancement in the development of organic solar cells and photovoltaic technology as a promising alternative to conventional solar cells, based on silicon and other inorganic semiconducting materials. Among the different types of organic semiconducting materials, porphyrins and BODIPY-based small molecules and conjugated polymers attract high interest as efficient semiconducting organic materials for dye sensitized solar cells and bulk heterojunction organic solar cells. The highest power conversion efficiency exceeding 9% has be…
Synergies and compromises between charge and energy transfers in three-component organic solar cells
2020
In this paper, we developed different three-component organic heterojunction structures supported by PET/ITO substrates with the aim to study the possible synergies and/or compromises between charge transfer (CT) and energy transfer (ET) processes in organic solar cells (OSCs). As components, we employed poly(3-hexylthiophene-2,5-diyl) (P3HT; donor), [6,6]-phenyl-C61-butyric acid methyl ester (PCBM; acceptor) and poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) that is known to give good ET to P3HT. At first, we observed that in a planar heterojunction (PHJ) solar cell, F8BT has to be properly located in between P3HT and PCBM to get a cascade energy level configuration allowing for a b…
Influence of the Preparation Method on Planar Perovskite CH 3 NH 3 PbI 3-x Cl x Solar Cell Performance and Hysteresis
2017
The present research has been supported by the State Research Programme “LATENERGI” and National Research Programme “Multifunctional Materials and Composites, Photonics and Nanotechnology (IMIS2)”.