JP7743673B2 - Photoelectric conversion devices - Google Patents

Description

The present invention relates to a photoelectric conversion device .

Lead halide perovskite semiconductors have attracted attention as nanocrystalline structures with high photoelectric conversion efficiency. Optical devices using halide perovskite crystals can be fabricated by solution coating, allowing for low-cost production, but improving stability remains a challenge. Various hole-transport materials are being researched to ensure stable operation of perovskite solar cells.

In solar cells using organic lead halide perovskite, a configuration has been proposed in which a polymethyl methacrylate (PMMA) layer is inserted between the perovskite layer and the hole transport layer to improve energy conversion efficiency (see, for example, Non-Patent Document 1). Meanwhile, in solar cells using lead sulfide (PbS) quantum dots, a configuration has been proposed in which a graphene oxide layer is inserted between the light absorption layer and the anode to function as the hole transport layer (see, for example, Non-Patent Document 2), and a configuration in which a composite of graphene oxide and PEDOT:PSS (polyethylenedioxythiophene:polystyrenesulfonate) is used as the hole transport layer (see, for example, Non-Patent Document 3).

J. Phys. Chem. C 2017, 121, 1562-1568 Organic Electronics 2018, 58, 270-275 Nanoscale, 2016, 8, 1513-1522

The present invention aims to provide a new polymer-graphene oxide composite material that contributes to improving energy conversion efficiency, as well as a method for producing the same.

In one embodiment, in a polymer-graphene oxide composite material in which a composite of a polymer and graphene oxide is dispersed in a solvent,
the polymer is selected from polymethyl methacrylate, polystyrene, spirobifluorene (spiro-MeOTAD), polyvinyl alcohol, poly(acrylamide), poly(e-caprolactone), polylactic acid, and poly(lactide-co-glycolide);
The solvent is selected from isopropanol, ethyl acetate, acetone, chloroform, and tetrahydrofuran.

In another embodiment, a method for making a polymer-graphene oxide composite comprises:
Dissolving a powder of a polymer selected from polymethyl methacrylate, polystyrene, spiro-MeOTAD, polyvinyl alcohol, poly(acrylamide), poly(e-caprolactone), polylactic acid, and poly(lactide-co-glycolide) in a solvent selected from isopropanol, ethyl acetate, acetone, chloroform, and tetrahydrofuran;
Graphene oxide powder is added to the solvent in which the polymer powder is dissolved, and the mixture is subjected to ultrasonic treatment to obtain a suspension in which a composite of the polymer and graphene oxide is dispersed.

A new polymer-graphene oxide (GO) composite material that contributes to improving energy conversion efficiency and a method for producing it have been developed.

FIG. 1 is a schematic diagram of the fabrication process of a polymer-GO composite material according to an embodiment. Schematic diagram of a sample made using a PMMA-GO composite material. FIG. 3 shows the Fourier transform infrared (FTIR) spectrum of the sample of FIG. 2, along with the FTIR spectra of a PMMA-only sample and a GO-only sample. This is an atomic force microscope (AFM) image of the PMMA-GO layer after coating and annealing. FIG. 10 is a diagram showing a comparison of the optical absorption spectrum of a sample according to the embodiment with that of a sample according to a comparative example. FIG. 2 is a diagram showing a photoelectron yield spectroscopy (PYS) spectrum of a sample according to an embodiment in comparison with a PYS spectrum of a sample according to a comparative example. FIG. 1 is a band structure diagram when a PMMA-GO layer according to an embodiment is applied to a photoelectric conversion device. FIG. 1 is a schematic diagram of a sample used for space charge limited current (SCLC) measurement. FIG. 1 shows the results of SCLC measurement. FIG. 10 shows the hole mobility of the quantum dot layer obtained by SCLC measurement. FIG. 10 is a diagram showing the defect density of a quantum dot layer obtained by SCLC measurement. FIG. 1 is a schematic diagram of a photoelectric conversion device to which a PMMA-GO composite material according to an embodiment is applied. FIG. 13 shows the C ⁻² −V characteristics of the device of FIG. 12 compared with the C ⁻² −V characteristics of a photovoltaic device without a PMMA-GO coating. FIG. 1 is a schematic diagram of another photoelectric conversion device to which the PMMA-GO composite material of the embodiment is applied. FIG. 15 shows the current-voltage characteristics of the device of FIG. 14. FIG. 1 is a graph showing the power conversion efficiency (PCE) of a photovoltaic device using a PMMA-GO coating according to an embodiment, compared with the PCE of a device without a PMMA-GO coating.

Embodiments of the present invention will be described below with reference to the drawings. The following description provides examples that embody the technical concept of the present invention, and does not limit the present invention to the configurations and numerical values described below.

Figure 1 is a schematic diagram showing the process for producing a polymer-GO composite material 15 according to an embodiment. In this embodiment, PMMA is used as the polymer to produce the PMMA-GO composite material 15. Solvents that can be used to disperse the PMMA-GO composite include isopropanol, ethyl acetate, acetone, chloroform, and tetrahydrofuran. In the following embodiment, isopropanol is used to produce the PMMA-GO composite material 15.

10 mg of PMMA powder 12 is added to 10 mL of isopropanol 11 and stirred at room temperature until the PMMA powder 12 is completely dissolved. In the actual sample preparation process, 10 mg of PMMA powder 12 was dissolved in 10 mL of isopropanol 11 by stirring at room temperature for 2 hours. PMMA powders of various sizes are commercially available. In this embodiment, PMMA powder with an average molecular weight of approximately 15,000 is used.

Next, 5 mg of GO powder 14 is added to the isopropanol solution 13 in which the PMMA powder 12 has been dissolved, and ultrasonic treatment is carried out for 30 to 90 minutes, preferably 40 to 80 minutes, and more preferably 50 to 70 minutes. This results in a PMMA-GO composite material 15, which is a suspension in which a PMMA-GO composite is dispersed in isopropanol. Various nanopowders of GO powder are commercially available, and in this embodiment, GO nanopowder with an average size of 6 to 14 μm manufactured by Tokyo Chemical Industry Co., Ltd. is used.

The PMMA-GO composite is a copolymer of PMMA and GO dispersed in isopropanol. The amounts of PMMA powder 12 and GO powder 14 added can be adjusted depending on the amount of isopropanol 11. The weight ratio of PMMA powder 12 to GO powder 14 is 5/1 to 2/1, and may be mixed in the range of 5/1 to 5/2.

The PMMA-GO composite material 15 obtained by the method shown in Figure 1 did not change in color or state of the suspension even when left in the air at room temperature for 30 minutes or more, confirming the stability of the PMMA-GO composite and the stability of its dispersion in the suspension.

By combining GO with a polymer such as PMMA, it is possible to impart the excellent properties of graphene to photovoltaic devices, namely, its unique band structure, which provides consistent absorption over a wide wavelength range of light, and extremely high electron mobility. To evaluate the presence of the PMMA-GO composite and its optical and electrical properties, a sample was prepared using the PMMA-GO composite material 15 prepared using the method shown in Figure 1.

<Confirmation of PMMA-GO layer>
Figure 2 is a schematic diagram of a sample 20 fabricated using a PMMA-GO composite material 15. A colloidal quantum dot (CQD) solution of lead sulfide (PbS) is applied to a glass substrate 21 to form a CQD layer 23. PbS quantum dots have a wide absorption spectrum in the near-infrared region and are applicable to photoactive layers in solar cells, infrared light-emitting devices, photodetectors, and the like.

100 μL of PMMA-GO composite material 15 is dropped onto the PbS CQD layer 23 and left for 1 second. Next, spin coating is performed for 15 minutes at a speed of 5000 rpm/s, increasing to 5500 rpm. After spin coating, the material is immediately annealed at 70°C for 2 minutes using a hot plate. This forms a PMMA-GO layer 24 with a thickness of approximately 10 nm on the CQD layer 23. A hole transport layer 25 of polyethylenedioxythiophene (PEDOT) is then formed on the PMMA-GO layer 24 by spin coating.

To confirm the presence of the PMMA-GO composite, we prepared a sample in which a PMMA layer was provided between the CQD layer 23 and the hole transport layer 25, and a sample in which a GO layer was provided between the CQD layer 23 and the hole transport layer 25. The former sample corresponds to the configuration described in Non-Patent Document 1, and the latter sample corresponds to the configuration described in Non-Patent Document 2.

Figure 3 shows the FTIR spectrum of a sample having a PMMA-GO layer 24 according to an embodiment, along with the FTIR spectra of a sample using a PMMA layer and a sample using a GO layer. In the FTIR spectrum of the sample according to the embodiment, a C=C bond peak is observed at 1635 cm ^-1 and the stretching vibration of the -OH group specific to PMMA is observed at 3419 cm ^-1 . Furthermore, vibrations of the axial strain C-H _x bond specific to aliphatic carbon are observed at 2990 cm ^-1 and 2950 cm ^-1 . The results in Figure 3 confirm the formation of a PMMA-GO layer 24 in which PMMA and GO are bonded.

Figure 4 shows an AFM image of the PMMA-GO layer after spin coating and annealing. Figures 4A and 4B are AFM images of the same sample at different in-plane positions. By applying the PMMA-GO composite material 15 of the embodiment, in which PMMA-GO complexes are dispersed, onto the CQD layer 23 and annealing it, the surface of the CQD layer 23 is almost completely covered with the PMMA-GO layer 24. It can also be seen that the surface of the CQD layer 23 is planarized by the PMMA-GO layer 24. This AFM image confirms that the PMMA-GO layer 24 formed from the PMMA-GO composite material 15 of the embodiment protects the interface of the PbS quantum dots in the CQD layer 23 while improving contact with the hole transport layer 25.

Figure 5 shows the optical absorption spectrum of Sample C of the embodiment, along with the optical absorption spectra of Samples A and B of the comparative examples. The horizontal axis represents photon energy (eV), and the vertical axis represents the absorption coefficient α. Sample C of the embodiment is a sample in which a PMMA-GO coating is applied to a PbS CQD layer 23, which is then annealed and washed with acetonitrile (ACN). Sample A of the comparative example is a sample that is not subjected to ACN washing or PMMA-GO coating, and has a hole transport layer 25 formed on the PbS quantum dot CQD layer 23. Sample B of the comparative example is a sample that is not subjected to PMMA-GO coating and is washed with ACN.

In sample B, the CQD layer 23 was cleaned with ACN without a PMMA-GO coating, resulting in an increased Urbach energy Eu of 31 meV. In contrast, in sample C of the embodiment, the CQD layer 23 is protected by the PMMA-GO layer 24, so even after ACN cleaning, the Urbach energy Eu is low at 23 meV. In sample A, although not coated with PMMA-GO, no ACN cleaning was performed, resulting in less damage to the CQD layer 23 and a low Urbach energy Eu of 24 meV.

The Urbach energy is expressed by the slope of the spectral tail in the region where the absorption coefficient α decreases rapidly. The smaller the Urbach energy, i.e., the steeper the rise in the absorption coefficient α, the less disorder there is in the atomic arrangement and the fewer defects there are. The results in Figure 5 show that the PMMA-GO layer 24 of this embodiment protects the CQD layer 23 and suppresses the occurrence of defects.

Figure 6 shows the PYS spectrum of sample C of the embodiment, along with the PYS spectra of comparative samples A and B. As in Figure 5, sample C is a sample that was subjected to ACN cleaning after being coated with PMMA-GO. Sample A is a sample that was neither coated with PMMA-GO nor cleaned with ACN, and sample B is a sample that was cleaned with ACN without being coated with PMMA-GO. The horizontal axis represents the energy near the valence band, and the vertical axis represents the density of states.

Sample B, which was cleaned with ACN without a PMMA-GO coating, has an increased density of states near the valence band of the CQD layer 23, i.e., an increased hole trap level density, compared to sample A, which was not cleaned with ACN. In contrast, sample C of the embodiment, which incorporates a PMMA-GO layer 24 at the interface of the CQD layer 23, significantly reduces the hole trap level density in the CQD layer 23, even after ACN cleaning. These measurement results demonstrate that the PMMA-GO layer 24 of the embodiment not only protects the QD layer, but also passivates the surface of the PbS quantum dots.

Figure 7 shows the band structure when the PMMA-GO layer 24 of this embodiment is applied to a photoelectric conversion device. Based on the configuration of sample 20 in Figure 2, ZnO is placed as a hole-blocking layer or electron-transport layer under the PbS CQD layer 23. A PbS-ethylenedithiol (EDT) layer is used as the hole-transport layer 25. By introducing the PMMA-GO layer 24 between the CQD layer 23 and the hole-transport layer 25, a gradient energy level favorable for hole transport is formed at the interface between the hole-transport layer 25 and the CQD layer 23. The high hole mobility in the PMMA-GO layer 24 and the hole-transport layer 25 significantly improves the current extraction rate of the device.

<Evaluation of electrical characteristics>
8 is a schematic diagram of a sample 30 used in space-charge-limited current (SCLC) measurements. The sample 30 has a device structure that extracts holes as minority carriers. The sample 30 has a hole-blocking layer 32, a PbS CQD layer 33, a PMMA-GO layer 34, and a hole-transport layer 35 stacked in this order on a first electrode 31. A second electrode 36 is provided on the hole-transport layer 35.

The first electrode 31 is made of indium tin oxide (ITO) with a thickness of 400 nm. The hole-blocking layer 32 is made of a 40 nm PEDOT:PSS layer. The CQD layer 33 is a PbS quantum dot layer with a thickness of 450 nm. The PMMA-GO layer 34 is a 10 nm thick layer obtained by applying and annealing a PMMA-GO composite material 15. After annealing the PMMA-GO layer 34, the surface is washed with ACN to form a hole-transport layer 35. The hole-transport layer 35 is a 40 nm PEDOT:PSS layer. The second electrode 36 is a 100 nm gold (Au) layer. The thicknesses of these layers are design values and include manufacturing tolerances.

Figure 9 shows the SCLC measurement results for Sample 30, along with those for a comparative example. Sample C is Sample 30 in Figure 8. Comparative example Sample A is a sample that was not coated with PMMA-GO or washed with ACN. Comparative example Sample B is a sample obtained by washing with ACN without forming a PMMA-GO layer.

The horizontal axis of Figure 9 is voltage (V), and the vertical axis is SCLC current density (J). When the injection barrier is low and a large amount of charge exists within the device, these become space charges and relax the electric field. When current limitation becomes dominant due to this field relaxation, the current is called SCLC. Figure 9 shows that the SCLC current density of sample C of the embodiment is low, while the SCLC current density of sample B, which was washed with ACN without a PMMA-GO layer, is high.

The hole mobility and defect density in the space charge limited region are automatically calculated based on the J-V characteristics in Figure 9. Figures 10 and 11 show the hole mobility and defect density, respectively, of the CQD layer 23 obtained by the SCLC measurement method in Figure 9. Referring to Figure 10, in sample C of the embodiment, the introduction of the PMMA-GO layer 34 increases the hole carrier density in the hole transport layer 35, promoting hole transport.

Sample A, which was not cleaned with ACN, suffered little damage to the CQD layer 23 even without the PMMA-GO layer 24, resulting in a high hole carrier density and hole mobility similar to that of sample C. On the other hand, sample B, which was cleaned with ACN without the PMMA-GO layer 34, suffered damage to the CQD layer 23 due to ACN, and was unable to achieve sufficient hole carrier density. The hole mobility of sample C in this embodiment is 2.4 times that of sample B.

Referring to Figure 11, in sample C of the embodiment, the CQD layer 33 is protected by the PMMA-GO layer 34 and the surface is passivated, resulting in a low defect density in the CQD layer 33. In sample B, which was cleaned with ACN without the PMMA-GO layer 34, the CQD layer 23 was damaged by the ACN, resulting in a high defect density in the CQD layer 33. In sample A, which was not cleaned with ACN, the CQD layer 23 was less damaged even without the PMMA-GO layer 24, resulting in a lower defect density compared to sample B, but not as low as sample C of the embodiment.

From Figures 9 to 11, it was confirmed that by using the PMMA-GO layer 24 of the embodiment, the interface between the PbS CQD layer 23 and the hole transport layer 25 is passivated, reducing the interface defect density and improving hole mobility. A low interface defect density means that recombination at the interface is suppressed, improving hole collection efficiency.

<Application to photoelectric conversion devices>
12 is a schematic diagram of a photoelectric conversion device 50 fabricated using a PMMA-GO composite material 15 according to an embodiment. The photoelectric conversion device 50 is, for example, a solar cell device. The photoelectric conversion device 50 includes a first electrode 51, a ZnO layer 52, a PMMA-GO layer 54, a CQD-EDT layer 53, and a second electrode 56 stacked in this order on the first electrode 51.

The first electrode 51 is formed of a transparent conductive film such as fluorine-doped tin oxide (FTO). The ZnO layer 52 is 50 nm thick and serves as a hole-blocking layer. The PMMA-GO layer 54 is formed by spin-coating and annealing the PMMA-GO composite material 15 of the embodiment and has a thickness of 10 nm. The PMMA-GO layer 54 acts as a barrier to electrons and promotes hole transport. By incorporating PMMA-GO as an underlayer of the CQD-EDT, damage to the CQD layer can be suppressed. The process of fabricating the CQD-EDT layer typically involves multiple uses of ACN, which damages the CQD photoactive layer. Introducing PMMA-GO as an underlayer of the CQD-EDT can suppress this damage. Furthermore, aligning the energy levels at the interface between the CQD photoactive layer and the CQD-EDT layer allows for efficient hole extraction. The CQD-EDT layer 53 functions as both a photoactive layer and a hole transport layer, and is 250 nm thick. The second electrode 56 is a 100 nm thick Au electrode.

13 compares the C ^-2 -V characteristics (data point E) of the photovoltaic device 50 of FIG. 12 with the C ^-2 -V characteristics (data point D) of a device without a PMMA-GO layer. Here, C is the capacitance generated in the depletion layer, which can be measured by a known impedance method. The intersection of the slope of the ^C-2 -V characteristics with the 1/ ^C2 = 0 axis is the built-in voltage, which indicates the potential difference across the depletion layer.

In the photoelectric conversion device 50 of the embodiment, the introduction of the PMMA-GO layer 54 increases the hole density of the CQD-EDT layer 53, which functions as a hole transport layer, from 3.02×10 ¹⁶ cm ⁻³ to 4.91×10 ¹⁶ cm ⁻³ . This improves the carrier mobility of the hole transport layer. It can be seen from FIG. 13 that the PMMA-GO layer 54 of the embodiment also has the effect of improving hole mobility when the CQD-EDT layer 53 is used.

Figure 14 is a schematic diagram of a photoelectric conversion device 60 that uses a PMMA-GO composite material according to an embodiment. The photoelectric conversion device 60 is, for example, a solar cell device. The photoelectric conversion device 60 has a ZnO layer 62, a CQD layer 63, a PMMA-GO layer 64, a CQD-EDT layer 65, and a second electrode 66 stacked in this order on a first electrode 61.

The first electrode 51 is formed of a transparent conductive film such as fluorine-doped tin oxide (FTO). The ZnO layer 52 is 50 nm thick and serves as a hole-blocking layer. The CQD layer 63 is a layer of PbS quantum dots and functions as a photoactive layer (or light-absorbing layer). The CQD layer 63 is 450 nm thick. The PMMA-GO layer 64 is formed by spin-coating and annealing the PMMA-GO composite material 15 of the embodiment and has a thickness of 10 nm. The CQD-EDT layer 65 is a hole-transporting layer and has a thickness of 50 nm. The second electrode 66 is a 100 nm thick Au electrode.

FIG. 15 shows the current-voltage characteristics of the photoelectric conversion device 60 shown in FIG. 14 . The open circles in the figure represent data points for the forward scan, and the black circles represent data points for the reverse scan. Under light irradiation, the potential was scanned between 0.0 V and 0.7 V. The measurement results for both the forward scan and the reverse scan are shown. The open-circuit voltage Voc, i.e., the voltage value at which the current density becomes zero, is 0.65 V for both the forward scan and the reverse scan. The short-circuit current density Jsc, i.e., the current density at zero voltage, is 32.3 mA/cm ² for the forward scan and 31.9 mA/cm ² for the reverse scan. Since the short-circuit current densities reported in Non-Patent Documents 1 and 2 are approximately 22.5 mA/cm ² , the short-circuit current density of the photoelectric conversion device 60 according to the embodiment is extremely high.

The fill factor (FF) is 71.3% in forward scanning and 71.6% in reverse scanning. The fill factor is the output (maximum output) at the optimal operating point divided by the product of the open-circuit voltage and short-circuit current, and is expressed as Pmax/Voc x Isc. While a fill factor closer to 100% is preferable, the photoelectric conversion device 60 of the embodiment achieves a fill factor exceeding 70%. The PCE in forward scanning is 14.79%, and the PCE in reverse scanning is 14.84%. PCE is the resulting electrical energy (power) divided by the energy of incident light. Compared to the PCE of 12.87% shown in Non-Patent Document 2 and 9.7% shown in Non-Patent Document 3, the PCE of the photoelectric conversion device 60 of the embodiment is significantly improved.

Figure 16 shows the PCE of a photoelectric conversion device 60 fabricated using the PMMA-GO composite material 15 of the embodiment, compared with the PCE of a photoelectric conversion device of PbS quantum dots that is not PMMA-GO coated or ACN washed. As described above, the photoelectric conversion device 60 of the embodiment exhibits an average PCE of 14.82% in the forward and reverse directions. In contrast, the device configuration without the PMMA-GO layer (W/O) has a lower PCE than the configuration of the embodiment. It can be seen that the use of a PMMA-GO layer increases hole collection efficiency and improves PCE.

As explained above, highly efficient quantum dot solar cells can be realized by passivating the interface between the CQD layer and the hole transport layer with a thin film of PMMA-GO composite. The procedure for producing the PMMA-GO composite material 15 of this embodiment is simple. A thin film that improves hole mobility can be easily formed by simply applying and annealing the PMMA-GO composite material 15. The PMMA-GO composite material 15 of this embodiment is applicable not only to solar cells, but also to optoelectronic devices in general that use quantum dots, including organic EL devices and infrared light-emitting elements.

Instead of isopropanol, ethyl acetate, acetone, chloroform, or tetrahydrofuran may be used as the solvent for preparing the PMMA-GO composite material 15. These solvents can be used to obtain a suspension in which PMMA and GO are dispersed. In addition to PMMA, other polymers that can form complexes with GO to improve carrier mobility include polystyrene, spirobifluorene (spiro-MeOTAD), polyvinyl alcohol, poly(acrylamide), poly(e-caprolactone), polylactic acid, and poly(lactide-co-glycolide). Dissolving these polymers in the aforementioned solvents, mixing the polymer solution with GO, and ultrasonicating the mixture can yield a suspension of a polymer-graphene oxide composite. Coating and annealing this suspension yields a polymer-GO thin film, which can be used to passivate the interface between the photoactive layer and the hole transport layer or the interface between the photoactive layer and the electron transport layer, thereby improving the performance of photovoltaic devices.

11: Isopropanol 12: PMMA powder 13: Isopropanol liquid in which PMMA powder 12 is dissolved 14: GO powder 15: PMMA-GO composite material 15
20, 30 Samples 31, 51, 61 First electrode 32 Hole blocking layer 33, 63 CQD layer (photoactive layer)
34, 54, 64 PMMA-GO layer 35 Hole transport layer 36, 56, 66 Second electrode 50, 60 Photoelectric conversion device 52, 62 ZnO layer (electron transport layer)
53 CQD-EDT layer

Claims (4)

A first electrode;
A second electrode;
a photoactive layer disposed between the first electrode and the second electrode;
a polymer-graphene oxide composite layer disposed between the photoactive layer and the first electrode or between the photoactive layer and the second electrode;
a hole blocking layer or an electron transport layer disposed between the first electrode and the photoactive layer;
a hole transport layer disposed between the second electrode and the photoactive layer;
and
the polymer-graphene oxide composite layer is disposed between the photoactive layer and the hole transport layer.
Photoelectric conversion device . A first electrode;
A second electrode;
a photoactive layer disposed between the first electrode and the second electrode;
a polymer-graphene oxide composite layer disposed between the photoactive layer and the first electrode or between the photoactive layer and the second electrode;
an electron transport layer disposed between the first electrode and the photoactive layer ;
and
the photoactive layer functions as a hole transport layer,
the polymer-graphene oxide composite layer is disposed between the photoactive layer and the electron transport layer;
Photoelectric conversion device . A first electrode;
A second electrode;
a photoactive layer disposed between the first electrode and the second electrode;
a polymer-graphene oxide composite layer disposed between the photoactive layer and the first electrode or between the photoactive layer and the second electrode;
and
The polymer-graphene oxide composite layer is a composite layer of graphene oxide and a polymer selected from polymethyl methacrylate, polystyrene, spirobifluorene (spiro-MeOTAD), polyvinyl alcohol, poly(acrylamide), poly(e-caprolactone), polylactic acid, and poly(lactide-co-glycolide).
Photoelectric conversion device . A first electrode;
A second electrode;
a photoactive layer disposed between the first electrode and the second electrode;
a polymer-graphene oxide composite layer disposed between the photoactive layer and the first electrode or between the photoactive layer and the second electrode;
and
the photoactive layer is formed of lead sulfide colloidal quantum dots;
Photoelectric conversion device .