Solar Energy Conversion Based On Organic And Organicinorganic Hybrid Solar Cells

Solar energy conversion based on organic and organic/inorganic hybrid solar cells has beenrnstudied in different types of photoelectrochemical cells (PECs). PECs that consist ofrnEu2+/Eu3+ and I3rn-/I- have been designed and studied for their photoresponse behavior. Inrndevices that consist of Eu2+/Eu3+ in methanol, liquid-state PECs using the emeraldine basernform of polyaniline (EB) as a photoactive material have been fabricated and studied for theirrnphotoresponse behaviors. The photoresponse of EB:Nc-TiO2-based PEC is significantlyrnhigher than that of EB-based and Nc-TiO2-based PECs. A PEC with a structure:rnGlass/ITO/EB:Nc-TiO2/Electrolyte/Pt produced an open circuit voltage (VOC) of 0.205 Vrnand short-circuit current (ISC) of 105 μA/cm2 under 50 mW/cm2 white light illumination.rnThe device showed an induced photon-to-current conversion efficiency (IPCE) of 80% andrn8% at 370 nm and 700 nm, respectively. Different systems of devices that consist of I3rn-/Ihavernbeen studied for their photoresponse behaviors. In liquid-state PECs, separate andrncomparative studies were conducted where the photoactive electrodes consist of chemicallyrnprepared poly[3-hexylthiophene], P3HT, and electrochemically prepared poly[3-(2’,5’-rndialkoxyphenyl)thiophenes]. In P3HT-based PECs, a comparative study was done betweenrncells consisting of photoactive electrodes of P3HT and a composite of nc-TiO2 and P3HT.rnP3HT based devices showed a VOC of 160 mV, an ISC of 2.4 μA/cm2 and a fill factor (FF) ofrn0.42 when illuminated with white light intensity of 100 mW/cm2. Nc-TiO2/P3HT basedrndevices showed better performance with a VOC of 0.51 V, an ISC of 0.31 mA/cm2, and a FFrnof 0.51 when illuminated under the same condition. The IPCE% obtained at 550 nm forrnP3HT-based devices and for nc-TiO2/P3HT-based devices were 0.18% and 4%,rnrespectively. In P3HT-based devices, P3HT showed its p-type behavior while in nc-rnTiO2/P3HT based devices, P3HT acted as a sensitizer to nc-TiO2. In poly[3-(2’,5’-rndialkoxyphenyl)thiophenes] based cells, poly[3-(2’,5’-dioctyloxyphenyl)thiophene], poly[3-rn(2’,5’-diheptyloxyphenyl)thiophene] and poly[3-(2’,5’-dibutyloxyphenyl)thiophene] werernelectrochemically deposited on nc-TiO2 coated ITO-glass. The redox properties of thernpolymers were characterized using cyclic voltammetry. The energy levels of the highestrnoccupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitalsrn(LUMO) have been estimated from their cyclic voltammograms and UV-Vis absorptionrnspectra. The poly[3-(2’,5’-dialkoxyphenyl)thiophenes] sensitize nc-TiO2 in liquid-state photoelectrochemical cells. The investigated polythiophenes with longer dialkoxyphenylrnsubstituents exhibited a lower photoelectrochemical cell performance. The results show thatrnthe expected better exciton and hole mobility of shorter polydialkoxyphenyl substitutedrnthiophenes can be used for solar cell application by improving the film properties of thernpolymers. In solid-state polymer-sensitized photoelectrochemical cells, we have designedrndevices where poly[2-methoxy-5-(2’-ethylhexyloxy)-1,4-phenylenevinylene], MEH-PPV,rnwas used as a sensitizer to TiO2 and as electron donor to C60. The ion-conducting polymer,rnpoly[oxymethylene-oligo(oxyethylene)] complexed with I3rn-/I- redox couple was used as arnsolid polymer electrolyte. It has been observed that PECs with a composite of the inorganicrnsemiconductors/MEH-PPV photoactive electrodes exhibit improved cell performances whenrncompared with MEH-PPV based PECs. Nc-TiO2/MEH-PPV based devices produced an ISCrnof 0.145 mA/cm2, and a VOC of 410 mV at light intensity of 100 mW/cm2. The powerrnconversion efficiency, the FF and the IPCE% were 0.03% and 0.5 and 1.8%, respectively.rnIn PECs based on MEH-PPV/C60, an IPCE% of 0.32% and a VOC of 281 mV and an ISC ofrn13.4 μA cm-2 were obtained at light intensity of 100 mW/cm2. Our results show thatrnorganic/inorganic hybrid PECs show improved performance when compared with organicrnbased PECs and polymer-sensitized PECs could be alternates in designing solar energyrnconversion devices.rnKeywords: Polymer-sensitized photoelectrochemical cell; Solar cell characteristics;rnElectrochemical polymerization; Semiconducting polymer; Nano-crystalline titaniumrndioxide; Buckminsterfullerene; Poly[oxymethylene-oligo(oxyethylene)]; Redox couple.

Get Full Work

Report copyright infringement or plagiarism