Topographical and morphological aspects of spray coated organic photovoltaics (original) (raw)
Related papers
In the last ten years, the highest efficiency obtained from organic photovoltaics (OPVs), such as bulk heterojunction polymer:fullerene solar cells, has risen from 2.5 to 11 %. This rapid progress suggests that the commercialization of OPVs should be realized soon if we can solve some technical issues. The advances in the development of OPVs can be attributed to four fronts: (i) a better understanding of the mechanism of photon-to-electron conversion; (ii) new materials with tailored energy levels and solubility; (iii) new processing approaches to induce optimal microstructures in the active layer; and (iv) new device architectures with novel interfacial layers. Herein, we review the materials, the microstructures of the active layers, the device structures, the interfacial layers that have been developed recently for OPVs, and provide future perspectives for this promising technology. The field of organic photovoltaics (OPVs) has progressed quite significantly in the last ten years, not only for their academic interest but also for their potential as an affordable energy technology, with high-throughput roll-to-roll solution processing driving down costs to the point of competitiveness with current technologies. Moreover, OPVs are light, can have tandem structures, and can be fabricated on plastic substrates, with flexibility to conform to the human body for potential applications in consumer electronics. Because OPVs can also be transparent or color-tunable, they can be integrated into building components for a variety of applications. Fig. 1 displays the evolution of the record efficiencies of single-and multi-junction organic solar cells; at present, the highest efficiency is near 11 % 1. Despite the advantages of and progress in the development of OPVs, several technical hurdles must be overcome prior to the successful launch of this promising technology to the market. In this review, we focus our attention mostly on polymer photovoltaics and some small molecule photovoltaics due to limited space. We discuss the basic mechanism for device operation; the relationship between material properties and power conversion efficiency (PCE); the molecular engineering of polymers and fullerenes; the microstructure of the active layer; the device structure and interfacial layers; and conclude with future perspectives.
Toward fully printed organic photovoltaics: processing and stability
The presence of a brittle and expensive ITO electrode is a limiting factor towards low cost OPV modules. Moreover, ITO layers on PET or PEN substrates are typically characterized by relatively high sheet resistances and the presence of large amounts of spikes that lead to efficiency losses. We have developed an alternative for the ITO anode, based on highly conductive PEDOT:PSS in combination with current collecting grids. Moreover, initial experiments indicate that the stability of ITO-free devices is higher than the stability of standard devices based on ITO. This work will ultimately contribute toward fully printed devices, which will provide low-cost manufacturing and improved stability of organic photovoltaics.
Thin Solid Films, 2016
Spray process is used for the deposition of Poly (3-hexylthiophene) (P3HT) and [6, 6] Phenyl-C 61-butyric acid methyl ester (PCBM) blend film under different voltages (0 V, 300 V, 500 V and 700 V) applied to the nozzle. The presence of the electric field during the spray process makes the P3HT:PCBM film smoother, uniform and more crystalline with well aligned domains. X-ray photoelectron spectroscopy study shows that PCBM rich surface is formed by application of the DC voltage (700 V) which improves the electron transport at the active layer and cathode interface. The application of electric field reduces the recombination at interfaces. The increased charge carrier separation between donor and acceptor at the interface and the crystallinity enhancement result in improved short circuit current density-voltage characteristics of Indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)
Performance of bulk heterojunction photovoltaic devices prepared by airbrush spray deposition
Applied Physics Letters, 2008
We have used airbrush spray deposition to fabricate organic photovoltaic devices with an active layer composed of a blend of poly(3-hexylthiophene) and [6,6]-phenyl-C61 butyric acid methyl ester. Working devices were prepared in ambient conditions from a variety of common organic solvents; active layers prepared from chlorobenzene exhibit improved homogeneity, resulting in narrower distributions of the relevant device parameters. Further studies on devices prepared from chlorobenzene showed that annealing at 120°C for 10min resulted in optimum performance, and that an active layer thickness of 150nm resulted in a maximum efficiency of 2.35% under AM1.5 illumination at 1sun.