Infrared photodiode and sensor and electronic device
An infrared photodiode includes a first electrode including a reflective layer, a second electrode facing the first electrode, and a photoelectric conversion layer between the first electrode and the second electrode. The photoelectric conversion layer includes an infrared absorbing material. A maximum absorption wavelength of the infrared absorbing material in a solution state is greater than about 700 nm and less than or equal to about 950 nm. The infrared photodiode is configured to exhibit an external quantum efficiency (EQE) spectrum in a wavelength region of greater than or equal to about 1000 nm.
1. An infrared photodiode, comprising:
a first electrode, the first electrode including a reflective layer;
a second electrode, the second electrode facing the first electrode; and
a photoelectric conversion layer between the first electrode and the second electrode, the photoelectric conversion layer including an infrared absorbing material,
wherein a maximum absorption wavelength of the infrared absorbing material in a solution state is greater than about 700 nm and less than or equal to about 950 nm, and
wherein the infrared photodiode is configured to exhibit an external quantum efficiency (EQE) spectrum in a wavelength region of greater than or equal to about 1000 nm.
2. The infrared photodiode of claim 1 , wherein
a peak wavelength of the EQE spectrum of the infrared photodiode is in a range of about 1000 nm to about 3000 nm, and
a full width at half maximum of the EQE spectrum of the infrared photodiode is in a range of about 5 nm to about 200 nm.
3. The infrared photodiode of claim 1 , wherein
the photoelectric conversion layer comprises
the infrared absorbing material, and
a counter material forming a pn junction with the infrared absorbing material,
the wavelength region of the EQE spectrum of the infrared photodiode is overlapped with a portion of a wavelength region of an absorption spectrum of the photoelectric conversion layer, and
a peak wavelength of the EQE spectrum of the infrared photodiode is longer than a peak wavelength of the absorption spectrum of the photoelectric conversion layer.
4. The infrared photodiode of claim 3 , wherein a difference between the peak wavelength of the EQE spectrum of the infrared photodiode and the peak wavelength of the absorption spectrum of the photoelectric conversion layer is greater than or equal to about 100 nm.
5. The infrared photodiode of claim 3 , wherein
the peak wavelength of the EQE spectrum of the infrared photodiode is in a range of about 1000 nm to about 3000 nm, and
the peak wavelength of the absorption spectrum of the photoelectric conversion layer is in a range of about 700 nm to about 1000 nm.
6. The infrared photodiode of claim 1 , wherein
the photoelectric conversion layer comprises
the infrared absorbing material, and
a counter material forming a pn junction with the infrared absorbing material,
a peak wavelength of the EQE spectrum of the infrared photodiode is at least partially defined by a composition ratio of the infrared absorbing material to the counter material, and
the peak wavelength of the EQE spectrum of the infrared photodiode is proportional to the composition ratio of the infrared absorbing material to the counter material, such that, as the composition ratio of the infrared absorbing material to the counter material increases, the peak wavelength of the EQE spectrum of the infrared photodiode shifts to a longer wavelength.
7. The infrared photodiode of claim 6 , wherein the composition ratio of the infrared absorbing material to the counter material is about 0.10 to about 1.00.
8. The infrared photodiode of claim 1 , wherein
a peak wavelength of the EQE spectrum of the infrared photodiode is at least partially defined by a thickness of the photoelectric conversion layer, and
the peak wavelength of the EQE spectrum of the infrared photodiode is proportional to the thickness of the photoelectric conversion layer, such that, as the thickness of the photoelectric conversion layer increases, the peak wavelength of the EQE spectrum of the infrared photodiode shifts to a longer wavelength.
9. The infrared photodiode of claim 8 , wherein the thickness of the photoelectric conversion layer is about 100 nm to about 500 nm.
10. The infrared photodiode of claim 1 , wherein
the second electrode comprises a semi-transmissive layer forming a microcavity with the reflective layer of the first electrode, and
a peak wavelength of the EQE spectrum of the infrared photodiode corresponds to a resonance wavelength of the microcavity.
11. The infrared photodiode of claim 10 , wherein
the second electrode comprises a light-transmitting auxiliary layer between the semi-transmissive layer and the photoelectric conversion layer, and
the peak wavelength of the EQE spectrum of the infrared photodiode is at least partially defined by a thickness of the light-transmitting auxiliary layer of the second electrode, and
the peak wavelength of the EQE spectrum of the infrared photodiode is proportional to the thickness of the light-transmitting auxiliary layer of the second electrode, such that, as the thickness of the light-transmitting auxiliary layer of the second electrode increases, the peak wavelength of the EQE spectrum of the infrared photodiode shifts to a longer wavelength.
12. The infrared photodiode of claim 11 , wherein the thickness of the light-transmitting auxiliary layer of the second electrode is about 5 nm to about 50 nm.
13. The infrared photodiode of claim 1 , wherein
the second electrode is a light-transmitting electrode,
the infrared photodiode further includes an optical auxiliary layer on the second electrode, the optical auxiliary layer forming a microcavity with the reflective layer of the first electrode, and
a peak wavelength of the EQE spectrum of the infrared photodiode corresponds to a resonance wavelength of the microcavity.
14. The infrared photodiode of claim 1 , wherein
the second electrode comprises an inorganic nanolayer facing the photoelectric conversion layer, and
the inorganic nanolayer comprises ytterbium (Yb), calcium (Ca), potassium (K), barium (Ba), magnesium (Mg), lithium fluoride (LiF), or an alloy thereof.
15. The infrared photodiode of claim 1 , wherein
the first electrode comprises a light-transmitting auxiliary layer between the reflective layer and the photoelectric conversion layer,
a peak wavelength of the EQE spectrum of the infrared photodiode is at least partially defined by a thickness of the light-transmitting auxiliary layer of the first electrode, and
the peak wavelength of the EQE spectrum of the infrared photodiode is proportional to the thickness of the light-transmitting auxiliary layer of the first electrode, such that, as the thickness of the light-transmitting auxiliary layer of the first electrode increases, the peak wavelength of the EQE spectrum of the infrared photodiode shifts to a longer wavelength.
16. The infrared photodiode of claim 15 , wherein
the thickness of the light-transmitting auxiliary layer of the first electrode is about 5 nm to about 50 nm.
17. The infrared photodiode of claim 1 , further comprising:
a buffer layer that is at least one of
between the first electrode and the photoelectric conversion layer, or
between the second electrode and the photoelectric conversion layer,
wherein a peak wavelength of the EQE spectrum of the infrared photodiode is at least partially defined by a thickness of the buffer layer, and
wherein the peak wavelength of the EQE spectrum of the infrared photodiode is proportional to the thickness of the buffer layer, such that, as the thickness of the buffer layer increases, the peak wavelength of the EQE spectrum of the infrared photodiode shifts to a longer wavelength.
18. The infrared photodiode of claim 17 , wherein
the thickness of the buffer layer is about 5 nm to about 200 nm.
19. The infrared photodiode of claim 1 , wherein
the infrared photodiode is configured to exhibit a peak wavelength of an EQE spectrum belonging to about 1000 nm to about 1300 nm, and
the infrared photodiode is configured to exhibit a maximum external quantum efficiency at the peak wavelength of the EQE spectrum, where the maximum external quantum efficiency is greater than or equal to about 5%.
20. The infrared photodiode of claim 1 , wherein the infrared absorbing material is a compound that is configured to have a temperature of less than or equal to about 500° C. at which a weight loss of 50% compared to an initial weight of the compound occurs during thermogravimetric analysis of the compound at an ambient pressure of less than or equal to about 10 Pa.
21. The infrared photodiode of claim 1 , wherein the infrared absorbing material is a coplanar compound including at least one quinoid moiety.
22. The infrared photodiode of claim 1 , wherein the infrared absorbing material is represented by Chemical Formula 1:
wherein, in Chemical Formula 1,
X is O, S, Se, Te, SO, SO 2 , NR a , CR b R c , or SiR d R e ,
Y 1 and Y 2 are each independently CR f or N,
Z 1 and Z 2 are each independently O, S, Se, Te, or NR g ,
Q is at least one substituted or unsubstituted 5-membered quinoid ring, at least one substituted or unsubstituted 6-membered quinoid ring, or a fused ring thereof,
R 1 and R 2 are each independently hydrogen, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C1 to C30 alkoxy group, a substituted or unsubstituted C1 to C30 thioalkoxy group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C3 to C30 heterocyclic group, a substituted or unsubstituted silyl group, a halogen, or any combination thereof,
R a to R g are each independently hydrogen, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C1 to C30 alkoxy group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C3 to C30 heterocyclic group, a substituted or unsubstituted silyl group, a halogen, a cyano group, or any combination thereof,
R 1 and R 2 are each independently present or combine with each other to form a ring,
R b and R c are each independently present or combine with each other to form a ring,
R d and R e are each independently present or combine with each other to form a ring, and
adjacent R f 's are each independently present or combine with each other to form a ring.
23. The infrared photodiode of claim 22 , wherein the infrared absorbing material is represented by Chemical Formula 1-1:
wherein, in Chemical Formula 1-1,
X is O, S, Se, Te, SO, SO 2 , NR a , CR b R c , or SiR d R e ,
R 1 and R 2 are each independently hydrogen, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C1 to C30 alkoxy group, a substituted or unsubstituted C1 to C30 thioalkoxy group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C3 to C30 heterocyclic group, a substituted or unsubstituted silyl group, a halogen, or any combination thereof,
R a to R e , R f1 and R f2 are each independently hydrogen, a substituted or unsubstituted C1 to C30 alkyl group, a substituted or unsubstituted C1 to C30 alkoxy group, a substituted or unsubstituted C6 to C30 aryl group, a substituted or unsubstituted C3 to C30 heterocyclic group, a substituted or unsubstituted silyl group, a halogen, a cyano group, or any combination thereof, and
n is an integer of 2 to 4.
24. A sensor, comprising:
a semiconductor substrate; and
the infrared photodiode of claim 1 on the semiconductor substrate.
25. An electronic device comprising the infrared photodiode of claim 1 .
26. An infrared photodiode, comprising:
a first electrode, the first electrode including a reflective layer;
a second electrode, the second electrode facing the first electrode; and
a photoelectric conversion layer between the first electrode and the second electrode, the photoelectric conversion layer configured to photoelectrically convert at least a portion of incident light,
wherein at least a portion of the infrared photodiode forms a microcavity with the reflective layer of the first electrode, the photoelectric conversion layer being between the first electrode and the portion of the infrared photodiode,
wherein the infrared photodiode is configured to exhibit an external quantum efficiency (EQE) spectrum having a wavelength region that includes a peak wavelength of the EQE spectrum of the infrared photodiode that corresponds to a resonance wavelength of the microcavity,
wherein the wavelength region of the EQE spectrum of the infrared photodiode is different from a wavelength region of an absorption spectrum of the photoelectric conversion layer.
27. The infrared photodiode of claim 26 , wherein the peak wavelength of the EQE spectrum of the infrared photodiode is longer than a peak wavelength of the absorption spectrum of the photoelectric conversion layer.
28. The infrared photodiode of claim 26 , wherein the second electrode comprises a semi-transmissive layer forming the microcavity with the reflective layer of the first electrode.
29. The infrared photodiode of claim 26 , wherein
the second electrode is a light-transmitting electrode, and
the infrared photodiode further includes an optical auxiliary layer on the second electrode, the optical auxiliary layer forming the microcavity with the reflective layer of the first electrode.
30. A sensor, comprising:
a semiconductor substrate; and
the infrared photodiode of claim 26 on the semiconductor substrate.
31. An electronic device comprising the infrared photodiode of claim 26 .