Organic Photodiode with High Infrared Light Sensitivity Based on Tin Phthalocyanine/C60 Bulk Heterojunction and Optical Interference Effect
We demonstrated an organic near-infrared (NIR) photodiode on the basis of the bulk heterojunction (BHJ) structure by using tin phthalocyanine (SnPc) and C 60 fullerene with a high incident photon--electron conversion efficiency (IPCE) of 50% at a wavelength of 750 nm. The cell showed optical respons...
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| Published in | Jpn J Appl Phys Vol. 51; no. 3; pp. 034103 - 034103-4 |
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| Main Authors | , , , , , |
| Format | Journal Article |
| Language | English |
| Published |
The Japan Society of Applied Physics
25.03.2012
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| Online Access | Get full text |
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| Summary: | We demonstrated an organic near-infrared (NIR) photodiode on the basis of the bulk heterojunction (BHJ) structure by using tin phthalocyanine (SnPc) and C 60 fullerene with a high incident photon--electron conversion efficiency (IPCE) of 50% at a wavelength of 750 nm. The cell showed optical responses to about 1000 nm and had a specific detectivity $D^{*}$ of $1.59 \times 10^{11}$ cm Hz 1/2 /W. The SnPc:C 60 ratio in the BHJ layer influenced the optical response. Higher ratios enhanced NIR sensitivity but reduced the peak IPCE; the optimal ratio was $3:1$. The optical interference of directly incident light and light reflected from an Al electrode was also examined to enhance the IPCE at longer wavelengths. With a 90-nm-thick C 60 layer, the first antinode of the standing wave at a wavelength of 750 nm was located at the BHJ layer; this layer enhanced the IPCE at 700 and 800 nm but reduced it at 400 nm. |
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| Bibliography: | (a) Structures of device and chemicals and (b) energy diagram of materials used in this study. IPCE spectra of SnPc-based cells with different SnPc:C 60 ratios in the photoactive mixed layer. IPCE data in the range of 810--890 nm were deleted because of artifacts due to the strong angulation of light intensities from the xenon lamp. Absorption spectra of SnPc:C 60 mixed thin films with the thickness of 50 nm. Their mixed ratios (SnPc:C 60 ) are $1:1$, $3:1$, $5:1$, and $1:0$. IPCE spectra of the cells with BP3T buffer layers of different thicknesses. The mixing ratio of the SnPc:C 60 layer is $1:1$. IPCE spectra of the cell with the 90-nm-thick C 60 and 15-nm-thick BP3T layers under different applied biases. The IPCE spectrum of the cell with the 10-nm-thick C 60 and 15-nm-thick BP3T layers is also shown. The mixing ratio of the SnPc:C 60 layer is $3:1$. The inset shows the current density--voltage ($J$--$V$) characteristics of the cell with the 90-nm-thick C 60 layer. |
| ISSN: | 0021-4922 1347-4065 |
| DOI: | 10.1143/JJAP.51.034103 |