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Efficient Two Layered Organic Photovoltaic Device

IP.com Disclosure Number: IPCOM000085960D
Original Publication Date: 1976-Jun-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 23K

Publishing Venue

IBM

Related People

Kaufman, FB: AUTHOR

Abstract

For organic light-absorbing species at a solid-solid interface, efficient photoactivated free-carrier generation has so far been limited by irreversibility (silver halide photography) or by the requirement of very high external fields (electrophotography). Yet the solar energy conversion apparatus of living plants manages to perform efficiently without these severe restraints. This appears to have occurred (at least in part) because the photon absorption and charge separation steps have been assigned to different organic molecular constituents, whose electronic structure is specific to these particular functions. The design of a potentially efficient organic solid-state photovoltaic device which makes use of these principles is hereinafter described.

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Efficient Two Layered Organic Photovoltaic Device

For organic light-absorbing species at a solid-solid interface, efficient photoactivated free-carrier generation has so far been limited by irreversibility (silver halide photography) or by the requirement of very high external fields (electrophotography). Yet the solar energy conversion apparatus of living plants manages to perform efficiently without these severe restraints. This appears to have occurred (at least in part) because the photon absorption and charge separation steps have been assigned to different organic molecular constituents, whose electronic structure is specific to these particular functions. The design of a potentially efficient organic solid-state photovoltaic device which makes use of these principles is hereinafter described.

Referring to the figure, light is absorbed in the photon absorption and transport layer 1 (PAT). Use of appropriate organic dyes or dye-like substituents allows selective tuning to get high-absorption coefficients over the desired wavelength region. By an energy transfer processes (well known to efficiently occur in organic crystalline solids, ordered multilayer arrays and polymers) the photon excitation is funnelled to the molecules at the CGS (charge generation and separation) interface 2.

The organic solid in the thin CGS layer 3 interacts (in its excited state) with electrode E(1) to give charge generation and separation. Depending on the Fermi level matching, holes or electrons are injected into electrode E(1). Reversibility and cycling of the process is accomplished via lateral electrode E(2), hence carrier mobilities along this direction of the CGS layer 3 must be large.

The advantages of this configuration are numerous and stem mainly from the ability to employ optimized materials for each function in the two layers. Localization of all charge generating excited...