Solar cells electron transfer

Nasr C., Vinodgopal K, Fisher L., Hotchandani S., Chattopadhyay A.K., Kamat P.V. Environmental photochemistry on semiconductor surfaces. Visible light induced degradation of a textile diazo dye, naphthol blue black, on Ti02 nanopartilces. J. Phys. Chem. 1996 100 8436-8442 Nasr S., Hotchandani S., Kamat P.V. The role of iodide in photoelectrochemical solar cells. Electron transfer between iodide ions and ruthenium polypyridyl complex anchored on nanocrystalline Si02 andSnOz films. J. Phys. Chem. B 1998 102 4944-4951... 

Ultrafast photoinduced electron transfer in semiconducting polymers mixed with controlled amounts of acceptors this phenomenon has opened the way to a variety of applications including high-sensitivity plastic photodiodes, and efficient plastic solar cells ... 

In two-component charge transfer systems, such as in the bulk-heterojuncdon solar cells presented here, deviations of the V,K. from the results of pristine single layer or bilayer devices are expected for two reasons first, some pan of the available difference in electrochemical energy is used internally by the charge transfer to a lower energetic position on the electron acceptor second, the relative posi-... 

Fig. 5.2 The n-Cd(Se,Te)/aqueous Cs2Sx/SnS solar cell. P, S, and L indicate the direction of electron flow through the photoelectrode, tin electrode, and external load, respectively (a) in an illuminated cell and (b) in the dark. For electrolytes, m represents molal. Electron transfer is driven both through an external load and also into electrochemical storage by reduction of SnS to metaUic tin. In the dark, the potential drop below that of tin sulfide reduction induces spontaneous oxidation of tin and electron flow through the external load. Independent of illumination conditions, electrons are driven through the load in the same direction, ensuring continuous power output. (Reproduced with permission from Macmillan Publishers Ltd [Nature] [60], Copyright 2009)...

Hyun et al. [345] prepared PbS Q-dots in a suspension and tethered them to Ti02 nanoparticles with a bifunctional thiol-carboxyl linker molecule. Strong size dependence due to quantum confinement was inferred from cyclic voltammetry measurements, for the electron affinity and ionization potential of the attached Q-dots. On the basis of the measured energy levels, the authors claimed that pho-toexcited electrons should transfer efficiently from PbS into T1O2 only for dot diameters below 4.3 nm. Continuous-wave fluorescence spectra and fluorescence transients of the PbS/Ti02 assembly were consistent with electron transfer from small Q-dots. The measured charge transfer time was surprisingly slow ( 100 ns). Implications of this fact for future photovoltaics were discussed, while initial results from as-fabricated sensitized solar cells were presented. 

Gratzel M (1994) NanocrystaUine solar cells. Renew Energy 5 118-133 Peter LM, Ponomarev EA, Franco G, Shaw NJ (1999) Aspects of the photoelectrochemistry of nanocrystalhne systems. Electrochim Acta 45 549-560 Peter L (2007) Transport, trapping and interfacial transfer of electrons in dye-sensitized nanocrystalline solar cells. J Electroanal Chem 599 233-240... 

Molecular engineering of ruthenium complexes that can act as panchromatic CT sensitizers for Ti02-based solar cells presents a challenging task as several requirements have to be fulfilled by the dye, which are very difficult to be met simultaneously. The lowest unoccupied molecular orbitals (LUMOs) and the highest occupied molecular orbitals (HOMOs) have to be maintained at levels where photo-induced electron transfer into the Ti02 conduction band and regeneration... 

Assuming that an efficient D-A type of molecule can be synthesized, it should be possible to deposit these molecules as a monolayer onto a glass slide coated with a metal such as aluminum or a wide bandgap semiconductor such as Sn(>2. With the acceptor end of the molecule near the conductor and with contact to the other side via an electrolyte solution it should be possible to stimulate electron transfer from D to A and then into the conductor, through an external circuit and finally back to D through the electrolyte. This would form the basis of a new type of solar cell in which the layer of D-A molecules would perform the same function as the p-n junction in a silicon solar cell (50). Only the future will tell whether or not this concept will be feasible but if nature can do it, why can t we ... 

Attaching perylene moieties as side groups allows achievement of high concentration without affecting the electronic structure of the polymer backbone. Putting 16% perylene moieties as side chains predictably results in more efficient energy transfer, observed with polymer 360, both in solution and solid state (emission band at 599 nm). Although no PLED device with 360 has been reported, this material showed excellent performance in solar cells (external photovoltaic QE = 7%, in blend with PPV) [434]. 

Figure 3.31. Organic solar cell with the molecular glass Spiro-MeOTAD as the solid-state electrolyte. The photosensitive ruthenium dye is attached as a monolayer to Ti02 nanoparticles, thus forming a large active area for photoinduced electron transfer.

D Souza, F. Ito, 0., Photosensitized electron transfer processes of nanocarbons applicable to solar cells. Chem. Soc. Rev. 2012,41 86-96. 

Chen, J. Lei, W. Zhang, X. B., Enhanced electron transfer rate for quantum dot sensitized solar cell based on CNT-Ti02 film./. Nanoscience andNanotechn. 2012,12 6476-6479. 

Figure 27 Sensitized solar cell based on dye-loaded zeolite L antenna systems. The antenna systems absorb light and transport their energy mainly along the c axis of the crystals to the semiconductor surface. Electron-hole pairs are formed in the semiconductor by energy transfer from the antenna system to the conduction band of the semiconductor.

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