Organic modulation element and modulation device
Provided is an organic modulation element including an organic modulation layer containing a plurality of organic semiconductor molecules, a first electrode, and a second electrode. Each of the plurality of organic semiconductor molecules is a molecule in which an excited state enabling reverse intersystem crossing from a lowest excited triplet state to a lowest excited singlet state is formed due to irradiation with the input light. In each of the plurality of organic semiconductor molecules, an intersystem crossing rate constant from the lowest excited singlet state to the lowest excited triplet state is greater than a reverse intersystem crossing rate constant from the lowest excited triplet state to the lowest excited singlet state, and the reverse intersystem crossing rate constant from the lowest excited triplet state to the lowest excited singlet state is greater than a non-radiative deactivation rate constant from the lowest excited triplet state to a ground state.
1 . A modulation device comprising:
an organic modulation layer containing a plurality of organic semiconductor molecules;
a first electrode having a light-transmitting property with respect to input light to the organic modulation layer, and disposed on one side of the organic modulation layer;
a second electrode disposed on the other side of the organic modulation layer; and
a controller configured to modulate a voltage to be applied between the first electrode and the second electrode,
wherein each of the plurality of organic semiconductor molecules is a molecule in which an excited state enabling reverse intersystem crossing from a lowest excited triplet state to a lowest excited singlet state in each of the plurality of organic semiconductor molecules is formed due to irradiation with the input light, and
the controller comprising circuitry configured to apply a voltage between the first electrode and the second electrode so that an electric field in a direction of causing charge separation occurs in the organic modulation layer, and thereby reduces light emission due to spontaneous emission from the organic modulation layer under irradiation with the input light.
2 . The modulation device according to claim 1 ,
wherein in each of the plurality of organic semiconductor molecules, a difference between energy of the lowest excited singlet state and energy of the lowest excited triplet state at an absolute temperature of 77 K is less than 0.3 eV.
3 . The modulation device according to claim 1 ,
wherein in each of the plurality of organic semiconductor molecules, the intersystem crossing rate constant from the lowest excited singlet state to the lowest excited triplet state is greater than a fluorescence rate constant from the lowest excited singlet state to the ground state.
4 . The modulation device according to claim 1 ,
wherein in each of the plurality of organic semiconductor molecules, the intersystem crossing rate constant from the lowest excited singlet state to the lowest excited triplet state is two or more times the reverse intersystem crossing rate constant from the lowest excited triplet state to the lowest excited singlet state.
5 . The modulation device according to claim 4 ,
wherein in each of the plurality of organic semiconductor molecules, the reverse intersystem crossing rate constant from the lowest excited triplet state to the lowest excited singlet state is 1×10 7 (sec −1 ) or less.
6 . The modulation device according to claim 1 ,
wherein a dipole moment of each of the plurality of organic semiconductor molecules is greater than 0 D.
7 . The modulation device according to claim 1 ,
wherein the organic modulation layer further contains a plurality of host molecules, and
energy of the lowest excited triplet state at an absolute temperature of 77 K in each of the plurality of host molecules is higher than energy of a lowest excited triplet state at an absolute temperature of 77 K in each of the plurality of organic semiconductor molecules.
8 . The modulation device according to claim 1 ,
wherein the second electrode has a light-transmitting property with respect to output light from the organic modulation layer.
9 . The modulation device according to claim 1 ,
wherein the first electrode has a light-transmitting property with respect to output light from the organic modulation layer.
10 . The modulation device according to claim 1 , wherein
the second electrode has a light-transmitting property with respect to output light from the organic modulation layer, and
a light-receiving layer is disposed on the other side of the second electrode, and configured to receive the output light.
11 . The modulation device according to claim 1 , wherein
the second electrode has a light-transmitting property with respect to output light from the organic modulation layer, and
a light-emitting layer is disposed on the one side of the first electrode, and configured to emit the input light.
12 . The modulation device according to claim 1 ,
wherein in each of the plurality of organic semiconductor molecules, an intersystem crossing rate constant from the lowest excited singlet state to the lowest excited triplet state is greater than a reverse intersystem crossing rate constant from the lowest excited triplet state to the lowest excited singlet state, and
in each of the plurality of organic semiconductor molecules, the reverse intersystem crossing rate constant from the lowest excited triplet state to the lowest excited singlet state is greater than a non-radiative deactivation rate constant from the lowest excited triplet state to a ground state.
13 . A modulation method comprising:
preparing an organic modulation element comprising an organic modulation layer containing a plurality of organic semiconductor molecules, a first electrode having a light transmitting property with respect to input light to the organic modulation layer and disposed on one side of the organic modulation layer, and a second electrode disposed on the other side of the organic modulation layer, wherein each of the plurality of organic semiconductor molecules is a molecule in which an excited state enabling reverse intersystem crossing from a lowest excited triplet state to a lowest excited singlet state in each of the plurality of organic semiconductor molecules is formed due to irradiation with the input light; and
modulating a voltage to be applied between the first electrode and the second electrode,
wherein, in modulating the voltage, a voltage is applied between the first electrode and the second electrode so that an electric field in a direction of causing charge separation occurs in the organic modulation layer, and thereby light emission due to spontaneous emission from the organic modulation layer under irradiation with the input light is reduced.