Organic tandem cell

Asymmetric Organic Tandem Cells Based on CuPc-Ceo PM-HJs... 

J-V characteristics in the dark and under various intensities of simulated AM1.5 solar illumination for an asymmetric organic tandem cell. 

A typical organic tandem cell consists of two subcells stacked on top of each other, each of which has different absorption range (Figure 12.8). The two subcells are connected in series via a thin recombination layer. Hence, better coverage of the solar spectrum and reduction of the thermalization loss can be realized due to the use of materials with different bandgaps. The total thickness of the active films in... 

Heliatek sets new world record efficiency of 10.7% for its organic tandem cell (press release April 27, 2012) http //www. heliatek.com/. p=1923 lang=en... 

Figure 11.2 Schematic representations of the regular and inverted device layouts for series-connected organic tandem cells. Under operation the indium tin oxide (ITO) electrode is biased positive with respect to the metal electrode in the regular configuration and negative in the inverted configuration. The difference is caused hy the positioning of the hole and electron collecting layers (HCL and ECL) with respect to photoactive layers. The intermediate contact formed hy HCL and ECL is referred to as the recombination layer. Note that in practice the device layout may vary from these schematics.

Xue JG, Uchida S, Rand BP, Forrest SR (2004) Asymmetric tandem organic photovoltaic cells with hybrid planar-mixed molecular heterojunctions. Appl Phys Lett 85 5757... 

Cheyns D, Rand BP, Heremans P (2010) Organic tandem solar cells with complementary absorbing layers and a high open-circuit voltage. Appl Phys Lett 97 3... 

Schueppel R, Timmreck R, Allinger N, Mueller T, Fumo M, Uhrich C, Leo K, Riede M (2010) Controlled current matching in small molecule organic tandem solar cells using doped spacer layers. J Appl Phys 107 6... 

Rand B. P., Peumans, P. and Forrest, S. R. (2004) Long-range absorption enhancement in organic tandem thin-film solar cells containing silver nanoclusters. J. Appl Phys., 96 7519-7526. 

The operation of tandem cells bears a close similarity to the processes that take place in photosynthesis where there are also two photosystems connected in series. In the first, light is absorbed by chlorophyll and this acts as a mediator to oxidize water to oxygen [reaction (4.21)], while in the second, the organic compound nicotinamide adenine dinucleotide phosphate (NADP) is reduced by electrons to a state generally designated NADPH. 

Device structure (a) and schematic energy level diagram (b) of a tandem organic PV cell with CuPc-Cjo planar-mixed molecular HJs. 

Layer Thicknesses (in A) of an Asymmetric Tandem Organic PV Cell Based on CuPc-C,o PM-HJs... 

Hiramoto, M., Suezaki, M., and Yokoyama, M. 1990. Effect of thin gold interstitial-layer on the photovoltaic properties of tandem organic solar-cell. Chemistry Letters 19 (3) 327-330. 

Xue, J., Uchida, S., Rand, B. R, and Forrest, S. R. 2004a. 4.2% Efficient organic photovoltaic cells with low series resistances. Applied Physics Letters 84 (16) 3013-3015. Xue, J., Uchida, S., Rand, B. R, and Forrest, S. R. 2004b. Asymmetric tandem organic photovoltaic cells with hybrid planar-mixed molecular heterojimctions. Applied... 

An interesting approach partially overcoming the problem of low conductivity and limited exciton diffusion widths is to combine two organic p-n junctions in series, leading to a tandem cell with a doubled photovoltage, compared to the simple p-n structure device [50]. 

In a number of studies, others and we have demonstrated that the performance of PSCs depends critically on the nanoscale organization and fimctionaUty of the photoactive layer, the interfaces with and type of the charge collecting electrodes, and the overall device architecture. For the last one, device performance can be improved, for example, by applying hole blocking layers [73], optical spacers to enhance light absorption in the layer of the same thickness [74, 75], and by using the tandem cell architecture [76-78], where two printable photovoltaic cells are added in series. In a tandem cell, it is possible to combine two, or more, thinner... 

Ameri, T. et al. (2009) Organic tandem solar cells a review. Energy Environ. Sci.,... 

Zhao, D.W. et al. (2008) Efficient tandem organic solar cells with an Al/MoOj intermediate layer. Appl. Phys. Lett.,... 

Hadipoitt, A. et al. (2006) Solution-processed organic tandem solar cells. 

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