Photodetectors for measuring real-time optical irradiance
A skin-wearable photodetector module includes an array with a plurality of photodetectors and a plurality of optical filters, and each photodetector is configured to receive an optical input from an optical filter having a central wavelength in a wavelength range of about 100 nm to about 1000 nm. Each photodetector includes a substrate with a first major surface having an electrode thereon, and a second major surface overlying an optical filter, an anode within an interior region of the electrode, an active layer including a. ternary mixture of an electron donor, an electron acceptor, and at least one charge carrier trap material, and a cathode that contacts the active layer.
1 . A skin-wearable photodetector module, comprising:
an array comprising:
a plurality of photodetectors; and
a plurality of optical filters,
wherein each photodetector of the plurality of photodetectors is configured to receive an optical input from an environment via an optical filter of the plurality of optical filters having a central wavelength in a wavelength range of about 100 nm to about 1000 nm, and
wherein each photodetector comprises:
a substrate defining a first major surface and a second major surface, wherein the second major surface overlies a corresponding optical filter of the plurality of optical filters;
an electrode overlying the first major surface of the substrate and defining an interior region;
an anode within the interior region of the electrode;
an active layer overlying the anode and comprising a ternary mixture of an electron donor, an electron acceptor, and at least one charge carrier trap material; and
a cathode overlying the active layer.
2 . The photodetector module of claim 1 , wherein each of the photodetectors of the plurality of photodetectors and a corresponding optical filter of the plurality of optical filters are within an encapsulating layer of a polymer.
3 . The photodetector module of claim 2 , wherein an external surface of the encapsulating layer comprises an adhesive layer.
4 . The photodetector module of claim 2 , further comprising a connector circuit encapsulated in the encapsulating layer and electrically coupled to the electrode.
5 . The photodetector module of claim 4 , wherein the connector circuit comprises an arrangement of serpentine electrodes.
6 . The photodetector module of claim 1 , wherein the charge carrier trap material comprises inorganic UV-absorbing particles.
7 . The photodetector module of claim 6 , wherein the active layer comprises a ratio by weight, based on a total weight of the active layer, of: about 1.0 parts of polymeric electron donor:about 0.5 to about 1.5 parts of a polymeric electron acceptor:greater than about 0 parts and up to about 5 parts of inorganic UV-absorbing particles.
8 . The photodetector module of claim 6 , wherein the inorganic UV-absorbing particles comprise ZnO.
9 . The photodetector module of claim 1 , further comprising an insulating layer separating the anode and the cathode,
wherein the insulating layer has a cylindrical shape, and
wherein the insulating layer encircles the anode and the active layer within an interior region of the cylindrical insulating layer.
10 . The photodetector module of claim 1 , wherein each of the optical filters has a central wavelength that differs by about 50 nm to about 100 nm over the wavelength range.
11 . The photodetector module of claim 1 ,
wherein the module is sufficiently stretchable such that a photocurrent and a dark current produced by the module varies no more than about ±10 μA under a tensile strain of up to about 30%,
wherein the module is sufficiently flexible such that a photocurrent produced by the module varies no more than about +10 μA at a curvature of up to about 1.5 cm −1 , and
wherein the module has an external quantum efficiency (EQE) of greater than 10% at a wavelength range of 300-700 nm at a bias voltage of −1 V.
12 . The photodetector module of claim 1 , wherein the substrate comprises a polymeric material that is transparent to incident light with a wavelength of about 100 nm to about 1000 nm.
13 . The photodetector module of claim 1 ,
wherein the first major surface of the substrate comprises a modified surface, and
wherein the modified surface has enhanced wettability to an anode material.
14 . The photodetector module of claim 1 , wherein the anode comprises a conducting or semiconducting polymer.
15 . The photodetector module of claim 1 ,
wherein the electron donor comprises a polythiophene, and
wherein the electron acceptor comprises a functionalized fullerene.
16 . The photodetector module of claim 1 , wherein the cathode comprises EGaIn.
17 . A photodetection system configured for removable attachment to human skin, the system comprising:
a skin-wearable photodetector module, comprising:
an array comprising a plurality of photodetectors and a plurality of optical filters, wherein each photodetector of the plurality of photodetectors is configured to receive an optical input from an environment via an optical filter of the plurality of optical filters having a central wavelength selected in a wavelength range of about 100 nm to about 1000 nm, and wherein each photodetector comprises:
a substrate defining a first major surface and a second major surface, wherein the substrate comprises a polymeric material that is transparent to incident light with a wavelength of about 100 nm to about 1000 nm, and wherein the second major surface of the substrate is adjacent to a corresponding optical filter of the plurality of optical filters;
a metal electrode overlying the first major surface of the substrate and comprising an interior region;
an anode overlying the first major surface of the substrate and the interior region of the metal electrode, wherein the anode comprises a conducting or semiconducting polymer;
a metal cathode; and
an active layer between the anode and the metal cathode, wherein the active layer comprises a ternary mixture of a polymeric electron donor, a polymeric electron acceptor, and inorganic UV absorbing particles, and wherein the active layer comprises a ratio by weight, based on a total weight of the active layer, of:
about 1.0 parts of polymeric electron donor:about 0.5 parts to about 1.5 parts of a polymeric primary electron acceptor:greater than about 0 parts and up to about 5 parts of inorganic UV absorbing particles;
a connector circuit electrically coupled to the metal electrode; and
an encapsulating layer encapsulating the plurality of photodetectors, the plurality of optical filters, and the connector circuit;
a connector electrically coupled to the connector circuit; and
a control console connected to the connector circuit, wherein the control console comprises a signal processing module, a data processing module, and a power supply.
18 . The photodetection system of claim 17 , wherein the power supply comprises at least one of:
a battery configured to provide power sufficient to operate the photodetection system for at least 24 hours; or
a solar cell.
19 . The photodetection system of claim 17 ,
wherein the inorganic particles consist essentially of ZnO, and
wherein the active layer comprises the ratio by weight, based on the total weight of the active layer, of about 1.0 parts of a polymeric electron donor:about 0.8 parts of a polymeric electron acceptor:about 1.0 parts to about 2.5 parts of inorganic particles.
20 . A method for real-time monitoring of optical irradiance in situ on skin of a patient, the method comprising:
applying a skin-wearable photodetector module to the skin of the patient, the photodetector module comprising:
an array comprising a plurality of photodetectors and a plurality of optical filters, wherein each photodetector in the array of the plurality of photodetectors is configured to receive an optical input from an environment via an optical filter of the plurality of optical filters having a central wavelength selected in a wavelength range of about 100 nm to about 1000 nm, and wherein each photodetector in the array of photodetectors comprises:
an active layer between a metal anode and a metal cathode, wherein the active layer comprises a ternary mixture of a polymeric electron donor, a polymeric electron acceptor, and a charge carrier trap material; and
monitoring, with the photodetector module, irradiance on the skin of the patient to diagnose or treat a medical condition.