Two step sintering process and metal grid design optimization for highly efficient ITO free organic photovoltaics (original) (raw)
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Embedded inkjet printed silver grids for ITO-free organic solar cells with high fill factor
Solar Energy Materials and Solar Cells, 2014
We combine inkjet printed silver grids and reverse nanoimprinting transfer to demonstrate front electrode structures embedded within the substrate for indium tin oxide (ITO) replacement in organic solar cells. The smooth interface between Ag grid and transparent semiconductor polymer PEDOT:PSS improves the topology of the successive layers. In turn, this results in overall good photovoltaic performance including high fill factor and no shunting. By modelling the shadowing and resistive losses as a function of the separation between grid lines, the optimal grid structure is identified, which we then confirm experimentally. Inkjet printed ITO-free solar cells showed slightly higher performance than the ITO based reference.
Applied Physics Letters, 2012
Towards an understanding of light activation processes in titanium oxide based inverted organic solar cells J. Appl. Phys. 112, 094503 (2012) Highly efficient indium tin oxide-free organic photovoltaics using inkjet-printed silver nanoparticle current collecting grids APL: Org. Electron. Photonics 5, 242 Analysis of a device model for organic pseudo-bilayer solar cells J. Appl. Phys. 112, 084511 Addition of regiorandom poly(3-hexylthiophene) to solution processed poly(3-hexylthiophene):[6,6]-phenyl-C61butyric acid methyl ester graded bilayers to tune the vertical concentration gradient APL: Org. Electron. Photonics 5, 235 Addition of regiorandom poly(3-hexylthiophene) to solution processed poly(3-hexylthiophene):[6,6]-phenyl-C61butyric acid methyl ester graded bilayers to tune the vertical concentration gradient
Solar Energy Materials and Solar Cells, 2010
We have demonstrated ink-jet printed indium tin oxide (ITO) electrode for cost-efficient organic solar cells (OSCs). By ink-jetting of crystalline ITO nano-particles and performing a rapid thermal anneal at 450 1C, we were able to obtain directly patterned-ITO electrodes with an average transmittance of 84.14% and a sheet resistance of 202.7 O/square without using a conventional photolithography process. The OSCs fabricated on the directly patterned ITO electrodes by ink-jet printing showed an open circuit voltage of 0.57 V, short circuit current of 8.47 mA/cm 2 , fill factor of 44%, and power conversion efficiency of 2.13%. This indicates that the ITO directly patterned by ink-jet printing is a viable alternative to sputter-grown ITO electrodes for cost-efficient printing of OSCs due to the absence of a photolithography process for patterning and more efficient ITO material usage.
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.
Fabrication of inkjet printed organic photovoltaics on flexible Ag electrode with additives
Solar Energy Materials and Solar Cells, 2014
In this paper, we describe organic photovoltaics (OPVs) based on flexible thin film Ag anodes that are fabricated using a controlled deposition of photoactive layer by inkjet printing. The inkjet printed OPV photo-active layer is a P3HT:PCBM blend incorporated with a high boiling point additive, 1,6-hexanedithiol which serves to allow improved morphology. The devices show comparable power conversion efficiency to those fabricated using spin-coating techniques. Optimization of procedures for OPV fabrication without ITO electrodes or spin-coating of the active layer is a vital step towards realizing the potential of OPVs for mass production.
High efficiency, fully inkjet printed organic solar cells with freedom of design
J. Mater. Chem. A, 2015
The organic photovoltaics field is maturing and reaching a technology readiness level where the focus is on developing large scale fabrication methods. In this light, fully inkjet printed organic solar cells were demonstrated. Inkjet printing allows direct patterning of all the layers, including the electrodes, offering full freedom of design without the use of masks or structuring by hardware. The semitransparent front and back electrodes consist of PEDOT:PSS and conductive Ag fingers, avoiding the use of ITO. The inkjet printing of six functional layer demonstrated minimal losses in performance as compared to the labscale standard, spin coated devices. All-inkjet printed large area (>1 cm 2 ) organic solar cells with power conversion efficiency of 4.1% deposited from environmentally friendly solvents in an air atmosphere are demonstrated for the first time. Organic solar cells were fabricated using industrial scale (512 nozzles) printheads, compatible with R2R technology. To prove the great advantage of inkjet printing as a digital technology allowing freedom of forms and designs, large area organic solar cells with different artistic
High-speed inkjet printing for organic photovoltaic devices
Inkjet printing is considered a promising technique for industrial production of Organic Photovoltaic (OPV) devices, especially due to its minimal consumption of materials, the easy modification of the numerical design and because this is a non-contact process. The objective of this study is to make efficient modules at a semi-industrial scale using 128 nozzle heads. In order to maximize the performance and lifetime, an inverted device structure was used consisting of: transparent plastic conductive substrate / N-layer / active layer / P-layer / silver electrode. Formulations and processes were therefore developed for substituting each spin-coated layer with an ink-jet printed layer. For 3.7 cm² cells power conversion efficiency (PCE) reaches 3.3 % with only N-layer printed, 2.4 % with only active layer printed, 3.0 % with only P-layer printed and 2.9 % with only the silver electrode printed. Three-cell modules of 11 cm² on 5x5 cm² substrates were also made. Most PCE reach >2 % for each inkjet printed layer.
Journal of Materials Science: Materials in Electronics, 2018
In this manuscript, we demonstrate screen printing, a low cost printing method, of PEDPOT:PSS as top transparent electrode which was integrated with organic solar cell devices fabricated on opaque steel substrates with device structure being Steel/Insulator/Al/ZnO/P3HT:PC 61 BM/PEDOT:PSS. To print PEDOT:PSS on the surface of hydrophobic active layer of P3HT:PC 61 BM, PEDOT:PSS is modified with isopropyl alcohol (IPA) and Fluorosurfactant Zonyl FS-300. Further, twostep annealing of screen printed PEDOT:PSS films, 50 °C for 5 min and then at 130 °C for 3 min, is found to be crucial in rendering low surface roughness. Adoption of these strategies together yielded PEDOT:PSS films of thickness in the range of 500-700 nm consistently with a roughness of ca. 55 nm. These PEDOT:PSS films were coupled with silver (Ag) grids in organic solar cell devices which yielded power conversion efficiency of ca. 0.7%.
ITO-free flexible organic solar cells with printed current collecting grids
Solar Energy Materials and Solar Cells, 2011
The presence of a transparent conductive electrode such as indium tin oxide (ITO) limits the reliability and cost price of organic photovoltaic devices as it is brittle and expensive. Moreover, the relative high sheet resistance of an ITO electrode on flexible substrates limits the maximum width of a single cell. We have developed an alternative ITO-free transparent anode, based on solution processed high conductive PEDOT:PSS in combination with a printed current collecting grid. The screen printed silver grid demonstrates a typical sheet resistance of 1 O/& with 6.4-8% surface coverage. The efficiency of a flexible device with an active area of 4 cm 2 with such a grid is much higher than a similar device based on ITO. Furthermore, as this composite anode is solution-processed, it is a step forward towards low-cost large area processing.
Journal of Materials Chemistry A, 2013
Fabrication of a flexible organic solar cell is demonstrated with an anode that is free of tin-doped indium oxide (ITO) by electrohydrodynamic (EHD) spraying of silver nanowires (Ag NWs). This methodology is applicable to fabricate patterned Ag NW thin-film electrodes for organic solar cells (OSCs). By optimizing the spray parameters and post-processing conditions, transparent electrodes with sheet resistances of 11UsqAˋ1(onglass)and11 U sq À1 (on glass) and 11UsqAˋ1(onglass)and20 U sq À1 (on polyethylene terephthalate, PET) and DC to optical conductivities of 70(onPET)canbeobtainedatanopticaltransmittanceof70 (on PET) can be obtained at an optical transmittance of 70(onPET)canbeobtainedatanopticaltransmittanceof80%. Bulk heterojunction OSCs are demonstrated with patterned Ag NW films serving as bottom transparent anodes on both glass substrates and flexible PET substrates. The photoactive layers are based on low band-gap polymers, poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b;4.5-b 0 ]dithiophene)-2,6-diyl-alt-(4-(2ehtylhexanoyl)-thieno[3,4-b]thiophene)]-2,6-diyl] and phenyl-C61-butyric acid methyl ester. Under AM 1.5 illumination, fabricated cells have high power conversion efficiencies of 5.27% (on glass) and 3.76% (on PET). This study indicates that a Ag NW electrode prepared by EHD spraying can serve as an alternative to the ITO electrode, which also enables its potential application in practical and flexible OSCs. † Electronic supplementary information (ESI) available: Preparation of P3HT:PCBM organic solar cells for obtaining efficient, ITO-free, exible organic solar cells. See