Photovoltaic action spectra of metal–phthalocyanine Schottky barrier cells

Abstract

We have measured the direct current (dc) action spectra of A1 and In/phthalocyanine ( a , P, and s-H?Pc and VOPc) photovoltaic cells in the wavelength range 400-900 nm. The data were analyzed in terms of both the local carrier generation and excitqn diffusion models. According to the local carrier generation model, photoactive barrier widths w of 390, 475, 310, and 950 A for In/u, P, s-HzPc, and VOPc, respectively, were obtained. Thc depletion region width of In-phthalocyanine Schottky junctions were independently measured using a dc discharge capacitance technique. In all cases. the depletion region widths (capacitance) were consistently smaller than the photoactive collection region widths (action spectra).~hese results suggest that excitons produced within a diffusion length of the barrier can diffuse into the barrier zone and dissociate into collectable~carriers. Using a combined local carrier gener:tion and exciton diffusion model, a barrier width of the order of 200-300 A and an exciton diffusion length of 300-500 A was estimated for In/x-HzPc cells.

Photoelectric Properties of ITO / CdS / Surfactant Aluminum Phthalocyanine / Au Solar Cells

“…The width of the depletion region at zero applied bias being Wo, the active region extends over a distance of Wo + A. In photoelectrochemical cells using SAIPc (13), a maximum value of -250~ was found for A, which agrees with A 300-500~ obtained for x-H2Pc (21,22). Figure 8 shows the efficiency variation (right axis), open-circuit voltage and short-circuit current density variation (left axis) with IT for an optimized cell.…”

Effects of Bulk Photoconductivity on Photocurrent Action Spectra of Molecular p-n Heterojunction Solar Cells

“…11,12 In condensed phthalocyanine layers, exciton diffusion length may depend on the fabrication conditions, and the reported L D values vary from 10 to 30 nm for ZnPc 7,13 and from 12 to 60 nm for CuPc films. 14,15 The photoexcitations created in the bulk of a thick molecular layer do not reach the interface region of the p-n junction and therefore do not contribute to the photocurrent of the device.…”

A new form of hydroxyaluminum phthalocyanine by acid treatment. Characterization and photoactivity

“…Metal-free phthalocyanine (PC) and many of its metal derivatives have attracted attention mainly due to their stability and their high absorption in the visible region. They were used in Schottky barrier junctions with aluminum, chromium, or indium as rectifying contacts (1)(2)(3)(4)(5)(6)(7)(8)(9)(10). Heterojunction photovoltaic cells of the type ZnO or CdS/Pc were shown to have efficiencies as high as 0.22% under AM2 illumination of 75 mW cmV2 (1 1-14).…”