Photoluminescence and Electroluminescence

Luminescence can be generated in a semiconductor electrode either, (a) by exciting an electron from the valence band to the conduction band by light absorption, or (b) via injection of minority carriers in an electrochemical process. In general, it has been observed with solid state devices that the luminescence originates from a radiative transition in the bulk. In the case of semiconductors with a direct bandgap, for example, GaAs, InP and CdS (see Appendix D), the luminescence corresponds mostly to a 

7 Charge Transfer Processes at the Semiconductor-Liquid interface 

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Numerous ternary systems are known for II-VI structures incorporating elements from other groups of the Periodic Table. One example is the Zn-Fe-S system Zn(II) and Fe(II) may substimte each other in chalcogenide structures as both are divalent and have similar radii. The cubic polymorphs of ZnS and FeS have almost identical lattice constant a = 5.3 A) and form solid solutions in the entire range of composition. The optical band gap of these alloys varies (rather anomalously) within the limits of the ZnS (3.6 eV) and FeS (0.95 eV) values. The properties of Zn Fei-xS are well suited for thin film heterojunction-based solar cells as well as for photoluminescent and electroluminescent devices. 

It was observed in other works that in sulfide electrolyte, decomposition of ZnSe was still obtained stable PECs could be constructed though from singlecrystal, n-type, Al-doped ZnSe electrodes and aqueous diselenide or ditelluride electrolytes [124]. Long-term experiments in these electrolytes were accompanied by little electrode weight loss, while relatively constant photocurrents and lack of surface damage were obtained, as well as competitive electrolyte oxidation. Photoluminescence and electroluminescence from the n-ZnSe Al electrodes were investigated. 

Strickert HH, Tong JR, EUis AB (1982) Luminescent photoelectrochemical cells. 6. Spatial aspects of the photoluminescence and electroluminescence of cadmium selenide electrodes. J Am Chem Soc 104 581-588... 

Ouyang J, Pan ERE, Bard AJ (1989) Semiconductor Electrodes, 62. Photoluminescence and electroluminescence from manganese-doped ZnS and CVD ZnS electrodes. J Electrochem Soc136 1033-1039... 

FIGURE 1.10 Optical absorption, photoluminescence and electroluminescence (circle) of Covion SY film. 

MR Andersson, G Yu, and AJ Heeger, Photoluminescence and electroluminescence of films from soluble PPY-polymers, Synth. Met., 85 1275-1276, 1997. 

D.M. Johansson, M. Theander, G. Srdanov, G. Yu, O. Inganas, and M.R. Andersson, Influence of polymerization temperature on molecular weight, photoluminescence, and electroluminescence for a phenyl-substituted poly(p-phenylene vinylenes), Macromolecules, 34 3716-3719, 2001. 

M. Hohloch, J.L. Segura, S.E. Dottinger, D. Honhholz, E. Steinhuber, H. Spreitzer, and M. Hanack, Design, synthesis and study of photoluminescence and electroluminescence of new poly(2,6-naphthylene vinylene) derivatives, Synth. Met., 84 319-322, 1997. 

A Bolognesi, C Botta, and M Martinelli, Oriented poly(3-alkylthiophene) films absorption, photoluminescence and electroluminescence behaviour, Synth. Met., 121 1279-1280, 2001. 

P. M. Fauchet, Porous Silicon Photoluminescence and Electroluminescent Devices C. Delerue, G. Allan, and M. Lannoo, Theory of Radiative and Nonradiative Processes in Silicon Nanocrystallites L. Bros, Silicon Polymers and Nanocrystals... 

Zhou Y, Tvingstedt K, Zhang EL, Du CX, Ni WX, Andersson MR, Inganas O (2009) Observation of a charge transfer state in low-bandgap polymer/fullerene blend systems by photoluminescence and electroluminescence studies. Adv Funct Mater 19 3293... 

Various arylene dihalides and heteroarylene dihalides are applicable to the reaction of bisallene 163, and polymers 164 of various structures are available in good to excellent yields (M of 15 000-22000 with PDI of ca. 2.0). Photoluminescent and electroluminescent properties of the polymer 164 are also studied. 

Fauchet PM (1998) Porous silicon photoluminescence and electroluminescent devices. In Semiconductors and semimetals, vol 49. Academic, San Diego, pp 206-252... 

Table 6. Photoluminescence and Electroluminescence Quantum Efficiencies of MEH-PPV, DSiPV, and Blended Polymers...

Copolymers containing alternating l,4-bis(phenylethenyl)benzene, l,4-bis(phenylethenyl)-2,5-dimethoxybenzene or l,5-bis(phenylethenyl)naphthalene chromophores, and dibenzo-24-crown-8 spacers within the polymer backbone, best represented by 87, showed blue light emission in solution, and tunable photoluminescence and electroluminescence depending on the structure of the chromophore. Blends of these copolymers with a small amount of poly(ethylene oxide), and lithium salt as active layers, form efficient light-emitting electrochemical cells <2003JMC800>. 

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