Wide bandgap polymer

V.S. Gevaerts, et al. Solution processed polymer tandem solar cell using efficient small and wide bandgap polymer fullerene blends. Advanced Materials, 2012 p. 1-5. 

Most wide bandgap polymers utilized in PLEDs require low work function cathode metals (e.g., Ca or Mg/Al) to provide proper injection of electrons. As shown recently, chemical reactions of these... 

Figure 11.8 Structures of wide bandgap polymers used in multi-junction polymer solar cells. References to the publications using these polymers can be found in Table 11.1.

P. Lu, H. Zhang, F. Shen, B. Yang, D. Li, Y. Ma, X. Chen, and J. Li, A wide-bandgap semiconducting polymer for ultraviolet and blue light emitting diodes, Macromol. Chem. Phys., 204 2274-2280, 2003. 

G. Grem and G. Leising, Electroluminescence of wide-bandgap chemically tunable cyclic conjugated polymers, Synth. Met., 57 4105-4110, 1993. 

The technique is suitable for depositing oxides of Pb, Co, Mn and Cr, and has been reported primarily for wide bandgap n-type oxide semiconductors, such as ZnO and TiOj. A number of the oxide deposits are electronically conductive and can be used as electrical contacts. Although not demonstrated, the process should also be suitable for semiconductors more commonly used in electronics. Imaging via oxidative photodeposition has also been reportedfor conductive organic polymers on ZnO and other semiconductors (37). The polymer forms on electrochemical oxidation of solutions of the monomer, e.g., pyrrole, thiophene and aniline. Since the conductive polymers are also electrochromic, the process might be... 

The next step was the use of solution processed charge transport layers in the recombination contact of polymer solar cells. In 2007, Gilot et al showed that ZnO nanoparticles processed from acetone can be covered with a layer of pH-neutral PEDOTrPSS spincoated from a dispersion in water to fabricate a ZnO/PEDOT PSS recombination layer that is transparent to light and makes an almost loss-less recombination layer for tandem and triple junction cells. This approach bears similarity to the p- and n-doped wide bandgap transport layers developed for evaporated small molecule tandem cells. The ZnO/PEDOT PSS recombination contact was initially employed in... 

The average for the small bandgap subcells of the tandem cells listed is 0.87 eV. This clearly demonstrates that Vqq and Fg are much better tuned for these small bandgap materials than for the wide bandgap materials where E = 1.07 eV. Particularly promising from an energetic point of view are some of the DPP polymers, where can be as small as 0.65 eV. 

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