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Numerical Analysis of Photoenhanced Electric Currents in Molecular Materials

100%

Jarosz G., Signerski R., Godlewski J.

Acta Physica Polonica A

1995

vol. 87

issue 4-5

855-860

This paper presents numerical calculations of photoenhanced current-applied voltage and photoenhanced current-light intensity characteristics with regard to the exciton diffusion length, lifetime of excitons and rate of exciton surface quenching. Dependencies of this type cannot be obtained analytically. It is shown that the increase in diffusion length causes the decrease in current in the case of strong surface quenching of excitons. Simultaneously, it is shown that the quality of crystals influences the photoenhanced current. A better quality of crystals causes the increase in the current in the case of weak surface quenching of excitons.

Charge Carrier Generation Caused by X-Rays in Organometallic Materials

88%

Godlewski J., Signerski R., Jarosz G., Stizza S., Berrettoni M.

Acta Physica Polonica A

1999

vol. 96

issue 2

295-301

Organometallic compounds play an exceptional role among organic compounds. Due to their structure a number of these compounds demonstrate interesting properties in various phenomena. Organometallic compounds show special properties in the case of X-ray absorption owing to considerable differences between the absorption coefficients of metals and light elements. The analysis of processes of charge carrier generation as a result of X-ray absorption in chosen organometallic compounds is the subject of this paper. Spectral dependences of charge carrier photogeneration efficiency around the Cu K-edge in copper phthalocyanine and copper acetylacetoniane have been specially considered. It has been observed that the photocurrent spectrum in these materials follows the absorption spectrum but mutual relation is not directly proportional. Experimental results connected with current-voltage and current-intensity characteristics have been analysed, as well. The obtained relationships have been compared with adequate results connected with charge carrier photogeneration in visible area and UV in organic materials. It has been observed that the X-ray photogeneration of charge carriers in the examined range of energy differs from the mechanisms of charge carrier generation in visible area and UV. The basic differences arise from the participation of secondary electrons, which are generated due to Auger electrons, Compton effect, and metal fluorescence. The process of charge carrier generation as a result of X-rays absorption is characterized by strong recombination of charge carriers in channels in which charge carriers are generated by high energetic secondary electrons.

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2 Acta Physica Polonica A

1 1999

1 1995

2 Godlewski J.

2 Jarosz G.

2 Signerski R.

1 Berrettoni M.

1 Stizza S.

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Numerical Analysis of Photoenhanced Electric Currents in Molecular Materials

Charge Carrier Generation Caused by X-Rays in Organometallic Materials