1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Energy level alignments and photocurrents in crystalline Si/organic semiconductor heterojunction diodes
Rent:
Rent this article for
USD
10.1063/1.3264945
/content/aip/journal/jap/106/11/10.1063/1.3264945
http://aip.metastore.ingenta.com/content/aip/journal/jap/106/11/10.1063/1.3264945
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Schematic device structure.

Image of FIG. 2.
FIG. 2.

EA magnitude as a function of diode bias for n-Si/Au diodes with MEH-PPV (top), PFO (middle), and Pc (bottom) organic layers. The EA null for Pc was determined by extrapolation of the reverse bias slope (dashed line) of the EA magnitude. The built-in potentials are 0.6 V (MEH-PPV), 0.7 V (PFO), and 0.75 V (Pc).

Image of FIG. 3.
FIG. 3.

Approximate energy level diagrams at zero bias for n-Si structures [left column, (a)–(d)] and for p-Si structures [right column, (e)–(h)]. The approximate electron affinities, ionization potentials, and work functions of the materials are indicated next to the appropriate energy level (e.g., Si electron affinity 4.05 eV) and the Fermi level is indicated by the dashed line at 4.3 eV (n-Si) and 4.9 eV (p-Si). For reference, (a) and (e) show bare Si surfaces (the surface is at right) treated by HF etching taken from Ref. 34. (b), (c), (f), and (g) are determined from a combination of the EA and capacitance-voltage measurements of the diodes in this work. The n-Si/Au structures [(b) and (c)] have near ideal vacuum energy level alignment. The p-Si/Al structures [(f) and (g)] have a large p-Si depletion region due to Fermi level pinning at the Si surface. For both Pc and the energy levels are shown crossing the Fermi level (by ) which is not physical. This crossing would produce charge transfer and electric fields in the materials that we have neglected because the potential changes are too small for us to definitively measure. For reference, (d) and (h) show typical metal/Si Schottky structures (from Ref. 28) for the metal contacts used in the organic diode structures.

Image of FIG. 4.
FIG. 4.

Current-voltage characteristics for n-Si/Au (top) and p-Si/Al (bottom) for MEH-PPV, PFO, Pc, and organic layers. The line styles used for each material in both graphs are the same. The inset (top) shows a numerical fit to the n-Si/Au MEH-PPV device using charge transport properties typical of MEH-PPV. The curves for the n-Si diodes are determined by the contact/organic energy barriers (Fig. 3) and the transport properties of the organic layers. In contrast, the p-Si diode characteristics are all essentially similar and determined primarily by the p-Si depletion region.

Image of FIG. 5.
FIG. 5.

EQE (left vertical axis) for an n-Si/MEH-PPV/Au diode at 0 bias. The right vertical axis shows 1-transmission for an equivalent MEH-PPV film on a glass substrate.

Image of FIG. 6.
FIG. 6.

EQE for an n-Si/MEH-PPV/Au diode at 2 V reverse bias (solid, left vertical axis) and for a reference Au/n-Si Schottky diode (dashed, right vertical axis).

Image of FIG. 7.
FIG. 7.

EQE (left vertical axis) for an n-Si/PFO/Au diode at 0 bias. The right vertical axis shows 1-transmission for an equivalent PFO film on a glass substrate.

Image of FIG. 8.
FIG. 8.

EQE (left vertical axis) for an n-Si/Pc/Au diode at 0 bias. The right vertical axis shows 1-transmission for an equivalent Pc film on a glass substrate.

Image of FIG. 9.
FIG. 9.

EQE (left vertical axis) for an diode at 0 bias. The right vertical axis shows 1-transmission for an equivalent film on a glass substrate.

Image of FIG. 10.
FIG. 10.

EQE for an diode at 1 and 5 V reverse bias. At 5 V reverse bias the quantum efficiency is from to 1000 nm due to photoconductive gain.

Image of FIG. 11.
FIG. 11.

EQE for an Au/n-Si Schottky diode at 0 and 5 V reverse bias. Unlike diodes there is very little increase in EQE as the bias is increased.

Image of FIG. 12.
FIG. 12.

EQE for a p-Si/MEH-PPV/Al diode at 0 bias (solid, left vertical axis) and for a reference Au/n-Si Schottky diode (dashed, right vertical axis).

Image of FIG. 13.
FIG. 13.

EQE for a p-Si/PFO/Al diode at 0 bias (solid, left vertical axis) and for a reference Au/n-Si Schottky diode (dashed, right vertical axis).

Image of FIG. 14.
FIG. 14.

EQE for a diode at 0 bias and 1 V forward bias (left vertical axis). The right vertical axis shows 1-transmission for an equivalent film on a glass substrate. The dominant photocurrent response changes from absorption in the Si (0 bias) to absorption in the (forward bias).

Loading

Article metrics loading...

/content/aip/journal/jap/106/11/10.1063/1.3264945
2009-12-02
2014-04-20
Loading

Full text loading...

This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Energy level alignments and photocurrents in crystalline Si/organic semiconductor heterojunction diodes
http://aip.metastore.ingenta.com/content/aip/journal/jap/106/11/10.1063/1.3264945
10.1063/1.3264945
SEARCH_EXPAND_ITEM