Photovoltaic & Optoelectronic Device Group

Abstract:

This Progress Report highlights recent developments in dye-sensitized solar cells composed of both liquid electrolytes and solid-state hole transport materials. The authors discuss and review the present understanding of and recent developments in the operational processes, such as charge generation, transport, recombination, and charge collection. Also, the merits and challenges of alternative device approaches are discussed, including extremely thin absorber cells, device containing inorganic p-type hole-transporters and non-TiO2 mesoporous metal-oxide electrodes employed in dye-sensitized solar cells. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.

Abstract:

Upon the addition of lithium salts to the hole-transporter matrix, 2, 2′, 7, 7′ -tetrakis (N,N -di- p -methoxypheny-amine)- 9, 9′ -spirobifluorene (spiro-MeOTAD), the authors observe a 100-fold increase in conductivity through spiro-MeOTAD within a Ti O2 mesoporous network. The authors demonstrate this to be a bulk effect and not due to improved injection at the electrodes. By testing "hole-only" diodes of pure spiro-MeOTAD and those doped with lithium salts, the authors calculate that the hole mobility increases from 1.6× 10-4 to 1.6× 10-3 cm2 V s. The authors discuss the possible mechanisms for this significant enhancement in charge mobility and its implication to the dye-sensitized solar cell operation. © 2006 American Institute of Physics.