Polymer solar cell comprising electron transport layer including novel diimide-based electrolyte

Abstract

The present invention relates to a polymer solar cell comprising an electron transport layer including a novel diimide derivative that comprises a naphthalene diimide or perylene diimide backbone. Since the polymer solar cell according to the present invention comprises an electron transport layer including an electrolyte composed of the diimide derivative, which can replace a ZnO thin film, a high-temperature process is not required during the manufacture of the polymer solar cell, and a high-efficiency inverted type polymer solar cell can be produced.

Description

Polymer solar cell having an electron transport layer containing a novel diimide-based electrolyte

[0001] The present invention relates to a polymer solar cell that uses a new material that replaces a conventional material in an electron transport layer interposed between a photoactive layer and a cathode.

[0002] Research is actively being conducted on methods to manufacture polymer solar cells (PSCs) using polymer organic materials as an alternative to silicon solar cells.

[0003] Polymer solar cells not only have excellent processability, versatility, and light weight, but are also economical in terms of material price, can be applied to flexible devices, and have the advantage of a relatively simple manufacturing process.

[0004] In general, inverted type polymer solar cells use ZnO thin films as electron transport layers, and ZnO thin films can be used at high temperatures (about 200 o C) is not suitable for the production of flexible polymer solar cells that require the use of polymer films.

[0005] The present invention aims to provide a polymer solar cell having an electron transport layer including a novel electrolyte that can replace a ZnO thin film as an electron transport layer of a polymer solar cell and does not require a high-temperature process.

[0006] To achieve the above technical task, the present invention provides a polymer solar cell having an electron transport layer including an electrolyte made of a diimide derivative compound between a cathode and an active layer.

[0007]

[0008] In addition, a polymer solar cell is provided, characterized in that the skeleton of the diimide derivative compound is composed of naphthalene diimide.

[0009]

[0010] In addition, a polymer solar cell is provided, characterized in that the diimide derivative compound including the naphthalene diimide backbone is represented by any one of the following chemical formulas 1 to 4.

[0011]

[0012] [Chemical Formula 1]

[0013]

[0014] [Chemical Formula 2]

[0015]

[0016] [Chemical Formula 3]

[0017]

[0018] (In the above chemical formula 3,

[0019] OTs - Is lim)

[0020] [Chemical Formula 4]

[0021]

[0022]

[0023] In addition, a polymer solar cell is provided, characterized in that the skeleton of the diimide derivative compound is composed of perlyene diimide.

[0024]

[0025] In addition, a polymer solar cell is provided, characterized in that the diimide derivative compound including the perylene diimide backbone is represented by any one of the following chemical formulas 5 to 9.

[0026]

[0027] [Chemical Formula 5]

[0028]

[0029] [Chemical Formula 6]

[0030]

[0031] [Chemical Formula 7]

[0032]

[0033] [Chemical Formula 8]

[0034]

[0035]

[0036] [Chemical Formula 9]

[0037]

[0038] (In the above chemical formula 9,

[0039] OTs - Is lim)

[0040]

[0041] Meanwhile, the polymer solar cell according to the present invention is not particularly limited in its laminated structure and materials of each layer, as long as it includes an electron transport layer containing the diimide derivative compound according to the present invention between the cathode and the photoactive layer.

[0042]

[0043] For example, it may be an inverted type polymer solar cell (iPSC) including a cathode formed on a transparent substrate; an electron transport layer including a compound represented by any one of the chemical formulas 1 to 9 below; an active layer having a donor and an acceptor; and an anode.

[0044]

[0045] To explain in more detail, the transparent substrate may be made of a transparent material with high light transmittance, and representative examples thereof include glass, polycarbonate, polymethylmethacrylate, polyethyleneterephthalate, polyamide, and polyethersulfone.

[0046]

[0047] In addition, the active layer may be formed as a double layer of a mixture including a donor that has excellent photoreactivity and can easily create excitons and an acceptor with high electron affinity, or may be formed as a heterojunction structure.

[0048] The above donor may be a conjugated polymer such as polythiophene, carbazole, benzothiadiazole, cyclopentadithiophene, diketopyrrolopyrrole, etc., and examples thereof include Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]](PTB7). Poly[3,6-bis(5-thiophen-2-yl)-2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-2,2'-diyl-alt-thieno[3,2-b]thiophen2,5-diyl](PDPP2T-TT), Poly(3-octylthiophene-2,5-diyl)(P3OT), Poly(p-phenylene vinylene)(PPV),Poly(dioctyl fluorene), Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene](MEHPPV), Poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene](MDMO-PPV), Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta [2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)](PCPDTBT),poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene-alt-5-octyl-4H-thieno[3,4-6-c]pyrrole-4,6(5H)-dione](PBDTTTPD), poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo-[c][1,2,5]thiadiazole)](PPDT2FBT), poly(3-hexylthiophene)(P3HT), poly{1-(5-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-6-methylbenzo[1,2-b:4,5-b']-dithiophen-2-yl)thiophen-2-yl)-5,7-bis(2-ethylhexyl)-3-(5-methylthiophen-2-yl)benzo-[1,2-c:4,5-c']dithiophene-4,8-dione}(PBDTBDDT) 및 Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione)](PBDB-TF, PM6) 등을 사용할 수 있다.;

[0049] In addition, fullerene derivatives such as C60, C70, C76, C78, ​​C82, C90, C94, C96, C720, C860, etc., which have high electron affinity, are also used as the above acceptors. Non-fullerene compounds such as 2,2'-((2Z,2'Z)-((12,13-bis(2-butyloctyl)-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y6BO) can be used.

[0050]

[0051] The above anode and cathode may be formed using metal oxides such as ITO (Indium Tin Oxide), SnO2, IZO (In2O3-ZnO), AZO (aluminum doped ZnO), GZO (gallium doped ZnO), aluminum (Al), transition metals such as silver (Ag), gold (Au), and platinum (Pt), rare earth metals, and semimetals such as selenium (Se), and it is preferable to form them taking the work function into consideration.

[0052]

[0053] Specific examples of the inverted polymer solar cell according to the present invention include an ITO substrate; an electron transport layer comprising a compound represented by any one of the chemical formulas 1 to 9; a donor comprising Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione)](PM6); and An example of a polymer solar cell is a polymer solar cell in which an active layer including an acceptor composed of 2,2'-((2Z,2'Z)-((12,13-bis(2-butyloctyl)-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y6BO); a hole transport layer including molybdenum oxide (MoO3); and a silver (Ag) electrode layer are sequentially laminated. At this time, a zinc oxide layer (ZnO layer) may be additionally included between the ITO substrate and the buffer layer.

[0054] The polymer solar cell according to the present invention has an electron transport layer including an electrolyte made of a diimide derivative including a naphthalene diimide or perlyene diimide backbone that can replace a ZnO thin film, thereby eliminating the need for a high-temperature process when manufacturing the polymer solar cell and enabling the production of a high-efficiency inverted type polymer solar cell.

[0055] Figure 1 is a drawing showing the process of synthesizing naphthalene diimide derivative compounds (NDIN-O, NDIN-Br, and NDIN-I) in Example 1.

[0056] Figures 2a to 2d are schematic diagrams of the device structure of the polymer solar cell manufactured in Example 1, the current density-voltage (JV) curve under illumination, the current density-voltage curve under dark conditions, and the incident photocurrent efficiency (IPCE) spectrum and J sc It is a curve of calculated values.

[0057] Figure 3 shows the effective voltage (V) of each polymer solar cell manufactured in Example 1. eff ) and photocurrent density (J ph ) is a curve showing the relationship between them.

[0058] Figure 4 shows the light intensity (P) of each polymer solar cell manufactured in Example 1. light ) and J SC This is a curve showing the relationship between the two.

[0059] Figure 5 is an impedance spectrum of each polymer solar cell manufactured in Example 1.

[0060] Figure 6 is a drawing showing the process of synthesizing naphthalene diimide derivative compounds (NDIN-OTs and NDIN-BS) in Example 2.

[0061] Figures 7a to 7d are schematic diagrams of the device structure of the polymer solar cell manufactured in Example 2, the current density-voltage (JV) curve under illumination, the current density-voltage curve under dark conditions, and the incident photocurrent efficiency (IPCE) spectrum and J sc It is a curve of calculated values.

[0062] Figures 8a and 8b show the effective voltage (V) of each polymer solar cell manufactured in Example 2, respectively. eff ) and photocurrent density (J ph ) and the curve showing the relationship between V eff Wow Jph / J sat This is a curve showing the relationship between the two.

[0063] Figures 9a and 9b show the light intensity (P) of each polymer solar cell manufactured in Example 2, respectively. light ) and J SC Curves showing the relationship between the light intensity (P light ) and V oc This is a curve showing the relationship between the two.

[0064] Figure 10 shows the results of a photostability aging test for each polymer solar cell manufactured in Example 2.

[0065] Figure 11 is an impedance spectrum of each polymer solar cell manufactured in Example 2.

[0066] Figure 12 is a chemical structural formula of perylene diimide derivative compounds (PDIN-I, PDIN-Br, and PDIN-BS) synthesized in Example 3.

[0067] Figures 13a to 13d are schematic diagrams of the device structure of the polymer solar cell manufactured in Example 3, the current density-voltage (JV) curve under illumination, the current density-voltage curve under dark conditions, and the incident photocurrent efficiency (IPCE) spectrum and J sc It is a curve of calculated values.

[0068] Figure 14 is a current density-voltage (JV) curve of each electron-only device manufactured in Example 3.

[0069] Figures 15a to 15d show the effective voltage (V) of each polymer solar cell manufactured in Example 3, respectively. eff ) and photocurrent density (J ph ) curve showing the relationship between V eff Wow J ph / J sat Curve showing the relationship between light intensity (P light ) and J SC Curves showing the relationship between the light intensity (P light) and V oc This is a curve showing the relationship between the two.

[0070] Figures 16a and 16b show the results of stability tests and thermal stability tests under ultraviolet (UV) exposure for each of the polymer solar cells manufactured in Example 3.

[0071] Figure 17 is an impedance spectrum of each polymer solar cell manufactured in Example 3.

[0072] Figure 18 is a chemical structural formula of perylene diimide derivative compounds (PDIN-I, PDIN-N, and PDIN-OTs) synthesized in Example 4.

[0073] Figures 19a and 19b are schematic diagrams of the device structure of the polymer solar cell manufactured in Example 4, the current density-voltage (JV) curve under illumination, the current density-voltage curve under dark conditions, and the incident photocurrent efficiency (IPCE) spectrum and J sc It is a curve of calculated values.

[0074] Figure 20 is a current density-voltage (JV) curve of each electron-only device manufactured in Example 4.

[0075] Figures 21a to 21d show the effective voltage (V) of each polymer solar cell manufactured in Example 4, respectively. eff ) and photocurrent density (J ph ) curve showing the relationship between V eff Wow J ph / J sat Curve showing the relationship between light intensity (P light ) and J SC Curves showing the relationship between the light intensity (P light ) and V oc This is a curve showing the relationship between the two.

[0076] Figure 22 shows the results of stability tests and thermal stability tests under ultraviolet (UV) exposure for each polymer solar cell manufactured in Example 4.

[0077] Figure 23 is an impedance spectrum of each polymer solar cell manufactured in Example 4.

[0078] In describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

[0079]

[0080] Embodiments according to the concept of the present invention may be modified in various ways and take various forms. Therefore, specific embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit embodiments according to the concept of the present invention to specific disclosed forms, and it should be understood that all modifications, equivalents, and alternatives included within the spirit and technical scope of the present invention are included.

[0081]

[0082] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the present invention. The singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises" or "has" indicate the presence of a described feature, number, step, operation, component, part, or combination thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0083]

[0084] Hereinafter, the present invention will be described in detail with examples.

[0085]

[0086] <Example 1>

[0087] In this example, naphthalene diimide derivatives (NDIN-O, NDIN-Br, and NDIN-I) were synthesized by introducing a quaternary ammonium ion and a counter anion (CA) into naphthalene diimide (Fig. 1), and an inverted polymer solar cell was manufactured using this as an electron transport layer material, and the cell characteristics, etc. were examined.

[0088]

[0089] 1. Synthesis of (2,7-bis(3-(dimethylamino)propyl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone) (NDIN)

[0090] 1,4,5,8-Naphthalenetetracarboxylic dianhydride (0.67 g, 2.5 mmol) and N,N′-dicyclohexylcarbodiimide (DCC) (1.24 g) were added to a 50 mL two-necked flask. After washing with a stream of dry argon, 10 mL of quinoline and N,N-dimethyl-1,3-propanediamine (0.94 mL, 7.5 mmol) were added, and the solution was stirred at 230 °C for 24 h. The reaction mixture was cooled to ambient temperature and then precipitated in water. After washing the precipitated solid with methanol and ethanol, bright yellow solid crystals were obtained with a yield of 75%.

[0091] 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.75 (s, 4H), 4.27 (t, 4H), 2.49 (t, 4H), 2.28 (s, 12H), 1.96 (m, 4H). 13C NMR (400 MHz, CDCl3) δ (ppm): 163.29 (C=O), 130.97, 126.78, 126.72 (aromatic ring), 57.33, 45.55 (CH2-N), 39.32 (CH3-N), 26.02 (CH2). Q-TOF-MS (APCI) m / z: calculated for [C 24 H 28 N4O4+ H] + : 437.22; found: 437.22.

[0092]

[0093] 2. Synthesis of NDIN-O, NDIN-Br, and NDIN-I

[0094] 100 mg of NDIN was dissolved in 3 mL of methanol, and an excess of hydrogen peroxide, bromoethane, or bromoethanol was added. The mixture was stirred at 90°C for 24 h. The solution was concentrated, precipitated in chloroform, and the precipitated solid was collected and dried. Isolated SM was obtained in 85-95% yield.

[0095] NDIN-O: 1 H NMR (400 MHz, MeOD) δ (ppm): 8.64 (s, 4H), 4.25 (t, 4H), 3.44 (m, 4H), 3.15 (s, 12H), 2.32 (m, 4H). 13 C NMR (400 MHz, MeOD) δ (ppm): 163.25 (C=O), 130.39, 130.46, 126.73 (aromatic ring), 68.13 (CH3-N), 57.18, 37.56 (CH2-N), 22.28 (CH2). Q-TOF MS (APCI) m / z: calculated for [C 24 H 28 N4O6+ H] + : 469.21; found: 469.21.

[0096] NDIN-Br: 1H NMR (400 MHz, MeOD) δ (ppm): 8.75 (s, 4H), 4.25 (t, 2H), 3.49 (m, 4H), 3.40 (dd, 4H), 3.32 (s, 12H), 2.23 (m, 4H), 1.35 (m, 6H). 13 C NMR (400 MHz, MeOD) δ (ppm): 163.26 (C=O), 130.46, 126.93, 126.83 (aromatic ring), 61.31, 59.74 (CH2-N), 49.29 (CH3-N), 37.31 (CH2-N), 21.55 (CH2), 7.02 (CH3). Q-TOF MS (APCI) m / z: calculated for [C 28 H 38 BrN4O4+ Na] + : 597.53; found: 597.05.

[0097] NDIN-I: 1 H NMR (400 MHz, DMSO-d6) δ (ppm): 8.69 (s, 4H), 4.11 (t, 2H), 3.37 (m, 4H), 3.28 (dd, 4H), 2.93 (s, 12H), 2.09 (m, 4H), 1.16 (m, 6H). 13 C NMR (400 MHz, DMSO-d6) δ (ppm): 163.54 (C=O), 131.07, 127.00, 126.81 (aromatic ring), 61.11, 59.59 (CH2-N), 50.06 (CH3-N), 38.04 (CH2-N), 21.79 (CH2), 8.49 (CH3). Q-TOF MS (APCI) m / z: calculated for [C 28 H 38 I2N4O4+ Na] + : 771.43; found: 771.09.

[0098]

[0099] 3. 유기태양전지(OSC) 제작

[0100] To fabricate an inverted OSC with a device structure of [ITO / ZnO or SM / active layer (PM6:Y6BO, 138 nm) / MoO3 (3 nm) / Ag (100 nm)], a ZnO layer was first deposited on an ITO substrate via a sol-gel process. Zinc acetate dihydrate (0.1 g) and ethanolamine (0.025 mL) were dissolved in 1 mL of methoxyethanol and stirred at 60°C for 12 h. A thin film of the ZnO sol-gel precursor was spin-coated at 4000 rpm for 60 s and then cured at 200°C for 10 min. The active layer was spin-casted at 1000 rpm for 60 s with a mixture of PM6:Y6BO (1:1.2 with 0.5% (v / v) 1-chloronaphthalene (CN) in 1 mL of chlorobenzene). The active solution was filtered through a 0.45 mm membrane filter before spin-coating. The MoO3 layer and the Ag layer were deposited at 2 × 10 -6 0.09 cm at Torr 2 Heat was continuously deposited through a shadow mask having a device area of ​​.

[0101]

[0102] 4. Fabrication of a single electron-only device

[0103] To investigate the electron mobility of the intermediate layer or ZnO layer, a single electron-only device having the structure of [ITO / ZnO or SM(5nm) / Y6BO(38nm) / Al(100nm)] was fabricated.

[0104]

[0105] 5. Experimental example

[0106] Thermogravimetric analysis (TGA) results showed that NDIN-Br and NDIN-I had excellent thermal stability with decomposition temperatures of 278°C and 263°C, respectively, whereas NDIN-O had very low thermal stability (T) due to the N-oxide amine group. d: 110℃). Low thermal stability may cause irreversible damage to the intermediate layer-cathode contact, which may deteriorate device stability.

[0107] To investigate the photovoltaic performance, inverted-structure OSCs with ITO / ZnO or SM / PM6:Y6BO / MoO3 / Ag structures were fabricated (Fig. 2a). Figures 2b and c show the current density-voltage (JV) curves of the devices under illumination and in the dark, respectively, and the photovoltaic parameters are summarized in Table 2.

[0108]

[0109] [Table 1]

[0110]

[0111] Experimental results showed that the intermediate layer in the range of 4 to 5.5 nm in thickness was beneficial to the performance of the PM6:Y6BO device, and 5.5 nm was the optimal thickness. A thick intermediate layer impedes charge transport from the active layer to the cathode, whereas a thin intermediate layer has less effect on charge collection. The NDIN-O-based device exhibited the lowest power conversion efficiency (PCE) of 11.1%. This is due to the poor thermal stability of NDIN-O, which begins to decompose at a low temperature (decomposition temperature = 110°C). Unlike conventional OSCs that do not consider thermal stability during device fabrication, in this embodiment, it is difficult to apply NDIN-O as an intermediate layer in an inverted structure device due to its poor thermal stability. In addition, the open circuit voltage (V) of the NDIN-O-based device oc ) (0.77 V) was observed to decrease significantly, which is V oc This is because the V of the photodiode is correlated with the lower work function (WF) value of the NDIN-O intermediate layer. According to the metal-insulator-metal (MIM) model, the V of the photodiode ocIt is worth noting that the PCE decreases due to the work function difference between the electrodes. In the device using NDIN-Br as an intermediate layer, the PCE is improved to 14.6%, similar to the PCE of the ZnO-based device (15.0%), and the short-circuit current density (J sc ) is 25.8 mA cm -2 , the open circuit voltage (Voc) was 0.81 V and the fill factor (FF) was 69.9%. The NDIN-I based device was J sc The device exhibited a PCE of 15.4%, which was the highest among SM-based devices. From these results, it can be concluded that the introduction of bromide and iodide as counter anions (CA) significantly improved the PCE of the device by overcoming the poor thermal stability of NDIN-O as the decomposition temperatures of NDIN-Br and NDIN-I increased.

[0112] In addition, the increase in PCE also implies a relationship between PCE and different CAs. In particular, PCE is significantly improved as the CA size of SM increases. In NDIN-I-based devices, J sc It should be noted that improvement was the most important. J sc The increase in J represents a typical transition from Schottky to Ohmic contact. Therefore, high J sc To obtain the Schottky barrier at the interface, an ohmic contact must be established. The incident photocurrent efficiency (IPCE) spectrum is shown in Fig. 2d, and the calculated Jsc values ​​are listed in Table 2. The measured J sc The results that the calculated values ​​from the IPCE spectrum are consistent support the accuracy of the PCE measurement results.

[0113] To evaluate the electron mobility of the devices, single-electron devices with ITO / ZnO or SM / Y6BO / Al structures were fabricated. The electron mobility was calculated according to the Mott-Gurney equation using the space-charge-limited-current (SCLC) method. The electron mobilities of the NDIN-O, NDIN-Br, and NDIN-I-based devices were 4.20 × 10 , respectively. -6 , 4.47 × 10 -5 and 1.53 × 10 -4 cm -2 V -1 s -1 The electron mobility of ZnO-based devices (8.71 × 10 -5 cm -2 V -1 s -1 ) was similar to J. The improved cathode modification function of the compound according to the present invention sc It can be linked to the trend of values.

[0114] Series resistance (R) of NDIN-O, NDIN-Br and NDIN-I based devices under 1.0 sun illumination condition, respectively. s ) values ​​are 6.73, 4.66 and 3.26 Ωcm 2 , and from this R s The value is J sc We confirmed that the shunt resistance (R) of NDIN-O, NDIN-Br, and NDIN-I based devices is closely related to the value sh ) values ​​are 0.274, 0.469, and 0.446 MΩcm, respectively. 2 As a ZnO-based device (0.497 MΩcm 2 ) showed lower values ​​than R. These R sh The trend of values ​​is consistent with the trend of device FF values, where lower values ​​are obtained when SM is applied compared to ZnO-based devices, indicating the possibility of leakage current in devices using SM as an intermediate layer. SM-based devices have lower R than ZnO-based devices.sh Higher J, which is lower in value but contributes mainly to PCE improvement sc The value was expressed.

[0115] To understand how charge moves and accumulates through the device, the effective voltage (V eff ) and photocurrent density (J ph ) was investigated. According to Fig. 3, log(V eff ) for log(J ph ) is low V eff In the domain, a linear relationship was observed and high V eff In the region, it started to saturate. The saturation photocurrent region (V) of devices based on NDIN-O, NDIN-Br, and NDIN-I, respectively sat ) of V eff The values ​​were 0.302, 0.257, and 0.214. These results are consistent with the trends in device performance. V eff When the saturation current density (J) is high sat ) is the maximum exciton generation rate (G max ), exciton dissociation probability, collection probability, and charge mobility. G max The value is J ph / q·L (q is the electron charge and L is the thickness of the active layer). J sat G obtained from NDIN-O, NDIN-Br and NDIN-I based devices under conditions max The values ​​are 1.09×10 each 27 , 1.17×10 27 and 1.26×10 27 m 3 s -1 is. Also, any V eff In J ph / J sat The exciton dissociation probability of the device calculated from the value is J scThe device performances based on ZnO, NDIN-O, NDIN-Br, and NDIN-I were 86.3, 75.5, 84.3, and 87.1%, respectively, under these conditions. These results demonstrate a reduction in charge recombination and an increase in charge collection at the interlayer interface.

[0116] J sc and V oc The light intensity (P) light ) dependence on J sc Dae P light and V oc Dae P light Measured using curves. Charge carrier recombination. J sc Wow P light The correlation between the equations is J sc ∝ (P light ) α can be explained as . Here, the value of α is closer to 1 when the recombination of bimolecular charges is negligible. Typically, polymer-based solar cells have a J α for light intensity in the range of 0.85 to 1. sc It exhibits a power law dependence of α, and bimolecular recombination, which causes some carrier loss, has been considered to be the cause of the deviation from α = 1. According to Fig. 4, the α value of the ZnO-based device was 0.990, and the α values ​​of the NDIN-O, NDIN-Br, and NDIN-I-based devices were 0.967, 0.978, and 0.991, respectively. Based on these results, the space charge at the interface of the SM-based device can be reduced to prevent bimolecular recombination from occurring in the device.

[0117] Understanding the recombination mechanism is crucial because photogenerated charge carriers are lost due to recombination. scIt is important to increase the performance of solar cells by consequently increasing the trap-assisted recombination. Shockley-Read-Hall recombination, also known as trap-assisted recombination, is the primary recombination mechanism that occurs when trap states are introduced into the band gap. V oc Dae P light The slope of the curve represents trap-assisted recombination. V oc Dae P light The relationship between V oc ∝ nk B T / qlnP light (n is the diode ideality factor, k B can be described by (where T is the temperature, q is the electron charge). When band-to-band recombination outweighs Shockley-Reed-Hall recombination, the slope is 1, and when only Shockley-Reed-Hall recombination occurs, the slope is 2. The slope value of the ZnO-based device was 1.173. The slope values ​​of the NDIN-O, NDIN-Br, and NDIN-I-based devices were 1.417, 1.261, and 1.154, respectively. This demonstrates that SM has succeeded in reducing the number of traps. It is also worth examining the slope value because it shows the same trend as the PCE value.

[0118] The carrier transport and recombination mechanisms were investigated by electrochemical impedance spectroscopy (EIS) measurements. Figure 5 shows the recombination resistance (R) under dark conditions. rec ) is shown. A semicircle without a transmission line indicates strong recombination in the device. R reccorresponds to the size of the EIS semicircle, which is proportional to the charge collection at the electrode / intermediate layer / active layer interface. R at zero bias measured at 0 V for devices based on ZnO, NDIN-O, NDIN-Br, and NDIN-I rec The values ​​were 447, 234, 430, and 401 kΩ, respectively. R rec The trend matches well with the FF of the device. R rec is related to the recombination site at the electrode / intermediate layer / active layer interface, and a higher value means a lower possibility of carrier recombination.

[0119]

[0120] <Example 2>

[0121] In this example, naphthalene diimide derivatives (NDIN-OTs and NDIN-BS) were synthesized by introducing a quaternary ammonium ion and a counter anion (CA) or a zwitterion into the naphthalene diimide side chain (Fig. 6), and an inverted polymer solar cell was manufactured using this as an electron transport layer material, and the cell characteristics, etc. were investigated.

[0122]

[0123] 1. Synthesis of NDIN

[0124] 1,4,5,8-Naphthalenetetracarboxylic dianhydride (0.67 g, 2.5 mmol) and N,N′-dicyclohexylcarbodiimide (DCC) (1.24 g) were added to a 50 mL two-necked flask. After washing with a stream of dry argon, 10 mL of quinoline and N,N-dimethyl-1,3-propanediamine (0.94 mL, 7.5 mmol) were added, and the solution was stirred at 230 °C for 24 h. The reaction mixture was cooled to ambient temperature and then precipitated in water. After washing the precipitated solid with methanol and ethanol, bright yellow solid crystals were obtained with a yield of 75% (0.82 g).

[0125] 1 H NMR (400 MHz, CDCl3) δ (ppm): 8.75 (s, 4H), 4.27 (t, 4H), 2.49 (t, 4H), 2.28 (s, 12H), 1.96 (m, 4H). 13 C NMR (400 MHz, CDCl3) δ (ppm): 163.29 (C=O), 130.97, 126.78, 126.72 (aromatic ring), 57.33, 45.55 (CH2-N), 39.32 (CH3-N), 26.02 (CH2). Q-TOF-MS (APCI) m / z: calculated for [C 24 H 28 N4O4+ H] + : 437.22; found: 437.22.

[0126]

[0127] 2. Synthesis of NDIN-OTs and NDIN-BS

[0128] 100 mg of NDIN was dissolved in 3 mL of methanol, and an excess of ethyl tosylate or 1,4-butanesultone was added. The mixture was stirred at 90°C for 24 h. The solution was concentrated, precipitated in chloroform, and the precipitated solid was collected and dried. Isolated SM was obtained in 85-95% yield.

[0129]

[0130] NDIN-OTs: 1 H NMR (400 MHz, MeOD) δ (ppm): 8.71 (s, 4H), 7.59 (d, 4H), 7.16 (d, 4H), 4.27 (t, 4H), 3.47 (m, 4H), 3.37 (dd, 4H), 3.03 (s, 12H), 2.32 (s, 6H), 2.23 (m, 4H), 1.35 (m, 6H). 13 C NMR (400 MHz, MeOD) d (ppm): 163.34 (C = O), 140.21 (CS), 130.42, 128.41, 125.57, 126.81, 120.43 (aromatic ring), 60.31, 59.50 (CH2-N), 49.27 (CH3-N), 37.43 (CH2-N), 21.39 (-CH3), 20.02(CH2), 7.03 (-CH3). Q-TOF MS (APCI) m / z: calculated for [C 42 H 52 N4O 10 S2+ Na] + : 860.01; Found: 859.30.

[0131] NDIN-BS: 1 H NMR (400 MHz, DO-d6) δ (ppm): 8.61 (s, 4H), 4.25 (t, 4H), 3.52 (t, 4H), 3.39 (t, 4H), 3.12 (s, 12H), 2.89 (t, 4H), 2.27 (m, 4H), 1.93 (m, 4H), 1.79 (m, 4H).13 C NMR (400 MHz, D2O) d (ppm): 165.97 (C = O), 131.17, 129.33, 125.98 (aromatic ring), 66.80, 65.01 (CH2-N), 50.71 (CH2-S), 49.95 (CH3-N), 33.71 (CH2-N), 26.53, 21.08 (CH2). Q-TOF MS (APCI) m / z: calculated for [C 32 H 44 N4O 10 S2+ Na] + : 731.84; Found: 731.24.

[0132]

[0133] 3. Fabrication of organic solar cells (OSCs)

[0134] To fabricate an inverted OSC with a device structure of [ITO / ZnO or SME / active layer (PM6:Y6BO, 138 nm) / MoO3 (3 nm) / Ag (100 nm)], a ZnO layer was first deposited on an ITO substrate via a sol-gel process. Zinc acetate dihydrate (0.1 g) and ethanolamine (0.025 mL) were dissolved in 1 mL of methoxyethanol and stirred at 60°C for 12 h. A thin film of the ZnO sol-gel precursor was spin-coated at 4000 rpm for 60 s and then cured at 200°C for 10 min. The active layer was spin-casted at 1000 rpm for 60 s with a mixture of PM6:Y6BO (1:1.2 with 0.5% (v / v) 1-chloronaphthalene (CN) in 1 mL of chlorobenzene). The active solution was filtered through a 0.45 mm membrane filter before spin-coating. The MoO3 layer and the Ag layer were deposited at 2 × 10 -6 0.09 cm at Torr 2 Heat was continuously deposited through a shadow mask having a device area of ​​.

[0135]

[0136] 4. Fabrication of a single electron-only device

[0137] To investigate the electron mobility of the intermediate layer or ZnO layer, a single electron-only device having the structure of [ITO / ZnO or intermediate layer / Y6BO(38nm) / Al(100nm)] was fabricated.

[0138]

[0139] 5. Experimental example

[0140] Thermogravimetric analysis (TGA) results confirmed that NDIN-OTs and NDIN-BS were thermally stable, with decomposition temperatures of 304°C and 338°C, respectively.

[0141] To investigate the photovoltaic performance, inverted-structure OSCs with the ITO / ZnO or SM (NDIN-OTs or NDIN-BS) / PM6:Y6BO / MoO3 / Ag structures were fabricated (Fig. 7a). Figures 7b and c show the current density-voltage (JV) curves of the devices under illumination and in the dark, respectively, and the photovoltaic parameters are summarized in Table 2.

[0142]

[0143] [Table 2]

[0144]

[0145]

[0146] For the device using NDIN-BS as an intermediate layer, a PCE of 14.5% was achieved, similar to the PCE of the ZnO-based device (15.0%), and J sc is 25.7 mA cm -2 , V oc was 0.81 V, and FF was 69.7%. The NDIN-OTs based device was J sc (24.5 mA cm -2) showed a PCE of 14.2% due to a significant decrease in the FF, but the FF was 70.8%, which was higher than that of the NDIN-BS-based device. Organic compounds containing tosylate anions are known to be soluble in polar solvents such as chlorinated hydrocarbons, methanol, ethanol, and isopropanol, which means that NDIN-OTs may have improved film-forming properties in the active layer. The low J of the NDIN-OTs-based device sc It can be seen that this is due to insufficient charge extraction due to work function mismatch and excessive contact resistance between the active layer and the electrode. The incident photocurrent efficiency (IPCE) spectrum is shown in Fig. 7d, and J sc The calculated values ​​are listed in Table 2. The measured J sc The results that the calculated values ​​from the IPCE spectrum are consistent support the accuracy of the PCE measurement results.

[0147] To evaluate the electron mobility of the devices, single-electron devices with ITO / ZnO or SME / Y6BO / Al structures were fabricated. The electron mobility was calculated according to the Mott-Gurney equation using the space-charge-limited-current (SCLC) method. The devices with NDIN-OTs and NDIN-BS had electron mobility of 1.44 × 10, respectively. -7 and 2.60 × 10 -7 cm -2 V -1 s -1 The electron mobility of ZnO-based devices (8.71 × 10 -5 cm -2 V -1 s -1 ) was similar to J. The improved cathode modification function of the compound according to the present invention sc It can be linked to the trend of values.

[0148] Series resistance (R) under 1.0 sun illumination condition of NDIN-OTs and NDIN-BS based devicess ) values ​​are 5.85 and 5.19 Ωcm, respectively. 2 , and from this R s The value is J sc We confirmed that the shunt resistance (R) of NDIN-OTs and NDIN-BS based devices is closely related to the value sh ) values ​​are 0.488 and 0.441 MΩcm, respectively. 2 As a ZnO-based device (0.497 MΩcm 2 ) showed lower values ​​than R. These R sh The trend in values ​​is consistent with the trend in device FF values, where lower values ​​are obtained when SM is applied compared to ZnO-based devices, indicating the possibility of leakage current in devices using SME as an intermediate layer.

[0149] To understand how charge moves and accumulates through the device, the effective voltage (V eff ) and photocurrent density (J ph ) was investigated. According to Fig. 8a, log(V eff ) for log(J ph ) is low V eff In the domain, a linear relationship was observed and high V eff In the region, it started to saturate. The saturation photocurrent region (V) of devices based on NDIN-OTs and NDIN-BS sat ) of V eff The values ​​were 0.259 and 0.255, respectively. These results are consistent with the trend of device performance. V eff When the saturation current density (J) is high sat ) is the maximum exciton generation rate (G max ), exciton dissociation probability, collection probability, and charge mobility. G max The value is J ph / q·L (q is the electron charge and L is the thickness of the active layer). Jsat G obtained from NDIN-OTs and NDIN-BS based devices under conditions max The values ​​are 1.10 × 10 each 28 and 1.14 × 10 28 m 3 s -1 And, the exciton dissociation probability of devices based on ZnO, NDIN-OTs and NDIN-BS was J sc The values ​​were 86.3%, 84.7%, and 84.2%, respectively, under the conditions (Fig. 8b). These results demonstrate the relationship between the reduction of charge recombination and charge collection at the intermediate layer interface.

[0150] J sc and V oc The light intensity (P) light ) dependence on J sc Dae P light and V oc Dae P light Measured using curves. Charge carrier recombination. J sc Wow P light The correlation between the equations is J sc ∝ (P light ) α can be explained as . Here, the value of α is closer to 1 when the recombination of bimolecular charges is negligible. Typically, polymer-based solar cells have a J α for light intensity in the range of 0.85 to 1. sc The power law dependence of α is shown, and bimolecular recombination, which causes some carrier loss, has been considered to be the cause of the deviation from α = 1. According to Fig. 9a, the α values ​​of ZnO, NDIN-OTs, and NDIN-BS-based devices were 0.990, 0.973, and 0.978, respectively. These results indicate that the reduced space charge at the interface of the NDIN-BS-based device compared to the NDIN-OTs-based device leads to the loss of photogenerated charge carriers due to de-recombination, which is why understanding the recombination mechanism is crucial. scIt is important to increase the performance of solar cells by consequently increasing the energy density. Shockley-Read-Hall recombination, also known as trap-assisted recombination, is a primary recombination mechanism in which one electron and one hole recombine through a trap state or recombination center. V oc Dae P light The slope of the curve represents Shockley-Reed-Hall recombination. V for devices with different intermediate layers oc Dae P light The slopes of the curves are shown in Fig. 9b. When only trap-assisted recombination occurs, the slope (n) is 2, but when interband recombination (Langevin) surpasses it, the slope (n) is 1. The n value of the ZnO-based device was 1.173, while the n values ​​of the NDIN-OTs-based and NDIN-BS-based devices were 1.395 and 1.302, respectively. This indicates that the number of traps is reduced in the NDIN-BS-based device compared to the NDIN-OTs-based device.

[0151] As shown in Fig. 10, the device was exposed to AM 1.5G simulated illumination (100 mA cm) in a nitrogen atmosphere. -2 ) were continuously exposed to light to perform photostability aging tests. At this time, PCE 100% represents the initial PCE value of a newly fabricated device for photostability test measurements. All devices were kept under continuous light exposure, and PCE was measured every 10 minutes. Devices based on NDIN-OTs and NDIN-BS showed photostability of approximately 65% ​​after 60 minutes of light exposure, while ZnO-based devices showed similar photostability (70%) after 60 minutes of exposure.

[0152] To fully understand the carrier transport and recombination process, devices based on NDIN-OTs and NDIN-BS were performed. Figure 11 shows the recombination resistance (R) obtained by fitting the data in the dark state. rec ) is shown. The absence of a transmission line in the semicircle indicates that the device has undergone significant recombination. R rec corresponds to the size of the EIS semicircle proportional to the charge collection at the electrode / intermediate layer / active layer interface. Calculated R at 0 V for devices based on ZnO, NDIN-OTs, and NDIN-BS, respectively. rec The values ​​were 447, 368, and 381 kΩ, respectively. R rec The trend matches well with the FF of the device. R rec The larger the value, the lower the probability that carriers will recombine at the recombination site at the electrode / interlayer / active layer interface.

[0153]

[0154] <Example 3>

[0155] In this example, perylene diimide derivatives (PDIN-O, PDIN-I, PDIN-Br, and PDIN-BS) were synthesized by introducing a quaternary ammonium ion and a counter anion (CA) or a zwitterion into the perylene diimide side chain (Fig. 12), and using these as electron transport layer materials, an inverted structure polymer solar cell was manufactured, and the cell characteristics, etc. were investigated.

[0156]

[0157] 1. Synthesis of PDIN

[0158] Dissolve 5 g of 3,4,9,10-perylenetetracarboxylic acid dianhydride in 100 ml of DMF, add 16 ml of N,N-dimethyl-1,3-propanediamine, and stir at 130°C for 12 hours. After cooling to room temperature, add 300 ml of THF, and remove the solution by filtration under reduced pressure from the formed precipitate. Then, wash three times with 300 ml of THF. Vacuum drying yielded a dark red solid in 94% yield.

[0159]

[0160] 2. Synthesis of PDIN-O, PDIN-I, PDIN-Br, and PDIN-B

[0161] 2.1 Synthesis of PDIN-O

[0162] 200 mg of PDIN was dissolved in 50 ml of ethanol, and 0.36 ml of H2O2 was added dropwise under an argon atmosphere. The mixture was stirred at room temperature for 30 minutes, and then at 60°C for 3 hours until the solution became transparent. After cooling to room temperature, the solution was removed under reduced pressure. The purple substance was purified by sequentially washing it three times with acetone and hexane, and then dried. A solid was obtained in a yield of 90%.

[0163] PDIN-O: 1 H NMR (400 MHz, MeOD, d, ppm): 7.22 (s, 4H, Ar), 6.79 (s, 4H, Ar), 3.80 (s, 4H, CH2(CH2)2NO(CH3)2), 3.22 (m, 4H, CH2NO(CH3)2), 3.18 (s,12H, CH3), 2.14 (m, 12H, CH2CH2NO(CH3)2). 13 C NMR (150 MHz, MeOD, d, ppm): 170.42, 163.52, 133.19, 130.60, 123.81, 128.21, 122.81, 122.36, 69.83, 58.80, 39.90, 23.86.

[0164]

[0165] 2.2 Synthesis of PDIN-I and PDIN-Br

[0166] 2.56 g of PDIN and methyl iodide or methyl bromide were dissolved in 130 ml of toluene and stirred for 12 hours in an argon atmosphere at 100°C. The mixture was cooled to room temperature, filtered with suction, washed with toluene, and dried under vacuum to obtain the product. This product was subjected to Soxhlet extraction with chloroform. The residue was dried under vacuum to obtain a brown-red solid in 81% yield.

[0167] PDIN-I: 1 H NMR (DMSO-d6, 400 MHz) d: 8.55 (4H, d), 8.33 (4H, d), 4.16 (4H, t), 3.48 (4H, m), 3.09 (18H, s), 2.19 (4H, m). 13 C NMR (DMSO-d6, 100 MHz, d) (ppm): 163.1, 134.7, 131.0, 128.9, 126.1, 124.0, 122.9, 64.3, 53.2, 37.4, 22.1.

[0168] PDIN-Br: 1 H NMR (MeOD-d, 400 MHz) d: 7.43 (4H, d), 7.12 (4H, d), 3.97 (4H, t), 3.57 (8H, t), 3.28 (12H, s), 2.21 (4H, m), 1.47 (6H, m). 13 C NMR (DMSO-d6, 100 MHz, d) (ppm): 136.1, 133.5, 130.7, 128.0, 124.2, 122.2, 88.3, ​​60.9, 50.0, 40.7, 21.7.

[0169]

[0170] 2.3 Synthesis of PDIN-BS

[0171] 100 mg of PDIN and 1,4-butane sultone were dissolved in 30 ml of chloroform and methanol (chloroform / methanol = 1:1, v / v). The mixture was stirred at 60°C for 3 days. After 3 days, the solvent was removed, and ethyl alcohol was added dropwise to the product. The mixture was filtered to obtain the pure product as a red solid in a yield of 62.1%.

[0172] 1 H NMR (400 MHz, CF3COOD): δ (ppm) 8.62-8.57 (m, 8H), 4.28-4.25 (t, J = 8.0 Hz, 4H), 3.51-3.49 (t, J = 4.0 Hz, 4H), 3.23-3.16 (m, 8H), 3.02 (s, 12H), 2.36-2.24 (m, 8H). 13 C NMR (100 MHz, CF3COOD): δ (ppm) 135.62, 132.65, 128.92, 125.86, 124.02, 121.56, 69.00, 66.04, 62.65, 62.50, 50.57, 43.25, 22.91, 17.90.

[0173]

[0174] 3. Fabrication of organic solar cells (OSCs)

[0175] To fabricate an inverted OSC with a device structure of [ITO / ZnO or SME / active layer (PM6:Y6BO, 138 nm) / MoO3 (3 nm) / Ag (100 nm)], a ZnO layer was first deposited on an ITO substrate via a sol-gel process. Zinc acetate dihydrate (0.1 g) and ethanolamine (0.025 mL) were dissolved in 1 mL of methoxyethanol and stirred at 60°C for 12 h. A thin film of the ZnO sol-gel precursor was spin-coated at 4000 rpm for 60 s and then cured at 200°C for 10 min. The active layer was spin-casted at 1000 rpm for 60 s with a mixture of PM6:Y6BO (1:1.2 with 0.5% (v / v) 1-chloronaphthalene (CN) in 1 mL of chlorobenzene). The active solution was filtered through a 0.45 mm membrane filter before spin-coating. The MoO3 layer and the Ag layer were deposited at 2 × 10 -6 0.09 cm at Torr 2 Heat was continuously deposited through a shadow mask having a device area of ​​.

[0176]

[0177] 4. Fabrication of a single electron-only device

[0178] To investigate the electron mobility of the intermediate layer or ZnO layer, a single electron-only device having the structure of [ITO / ZnO or intermediate layer / Y6BO(38nm) / Al(100nm)] was fabricated.

[0179]

[0180] 5. Experimental example

[0181] Thermogravimetric analysis (TGA) results showed that PDIN-O began to decompose at 100°C, whereas PDIN-I, PDIN-Br, and PDIN-BS, in which quaternary ammonium ions and zwitterions were introduced into the PDIN side chain, exhibited improved thermal stability.

[0182] In order to investigate the photovoltaic performance, an inverted structure OSC according to the present invention with the structure of ITO / PDIN derivative (5 nm) / PM6:Y6BO (100 nm) / MoO3 (3 nm) / Ag (100 nm) was fabricated as shown in Fig. 13a, and an inverted structure NFOSC with the structure of ITO / ZnO (25 nm) / PM6:Y6BO (100 nm) / MoO3 (3 nm) / Ag (100 nm) was used as a comparative example. 1.0 Solar illumination (100 mWcm -2 ) and the current density-voltage (JV) curves of the device in the dark state are shown in Figs. 13b and c, and the device performance and photovoltaic parameters are listed in Table 3.

[0183]

[0184] [Table 3]

[0185]

[0186] a Calculated using the IPCE curve

[0187] b series resistor

[0188] c Shunt resistance in cancer state

[0189]

[0190] The PCEs of the PDIN-I, PDIN-Br, and PDIN-BS-based devices were 15.5%, 15.0%, and 15.0%, respectively, which were almost identical to the PCE (15.0%) of the ZnO-based device, indicating that ZnO-free devices with similar performance to ZnO-based devices were successfully fabricated. These results demonstrate that PDIN derivatives are useful as materials for the cathode interlayer (CIL) in inverted structure devices, and that the modification of the counterion group overcomes the thermal stability issue of PDIN-O. J scThe improvement in FF significantly contributes to the device performance. The highest PCE is 15.5% obtained using PDIN-I as CIL, which is slightly higher than that of ZnO-based devices. This performance improvement is due to the J of PDIN-I-based devices. sc (28.2 mA cm -2 ) is a J of ZnO-based devices sc (25.9 mA cm -2 ) as compared to the PDIN-I based device. However, the FF of the PDIN-I based device was 68.6%, which was slightly lower than the FF (70.8%) of the ZnO based device. In addition, introducing quaternary ammonium ions and zwitterions into the PDIN backbone can improve the device performance compared to the PDIN-O based device. J sc The trend was consistent with the work function, J SC The values ​​were calculated using IPCE (Fig. 13d). The PCE of the PDIN-O-based device was 12.5%, which was lower than that of the devices using other intermediate materials. In such cases, a large voltage loss in the OSC may occur due to the potential across the device. In addition, the poor thermal stability of PDIN-O may reduce the PCE of the device. The V of ZnO, PDIN-I, PDIN-Br, PDIN-BS, and PDIN-O-based devices oc were 0.82, 0.80, 0.82, 0.82, and 0.78 V, respectively. In PDIN-O based devices, V oc A significant decrease in V oc It is correlated with the low work function value of the PDIN-O intermediate layer. To investigate the electron transport properties of the PDIN derivatives, single-electron devices with the structures of ITO / ZnO or PDIN derivative / Y6BO(38 nm) / Al(100 nm) were fabricated. The electron mobility of the ZnO-based devices was 0.87 × 10 -4 cm -2 V -1 s -1The electron mobilities of PDIN-I, PDIN-Br, PDIN-BS, and PDIN-O based devices were 1.71 × 10 -4 , 1 . 01 × 10 -4 , 0 . 89 × 10 -4 , and 0 . 02 × 10 -4 cm -2 V -1 s -1 As can be seen in Fig. 14, the electron mobility of the PDIN-I, PDIN-Br, and PDIN-BS-based devices was higher than that of the ZnO-based device, while the PDIN-O-based device showed the lowest electron mobility. The built-in potential, current density, and electric field represent the characteristics of SCLC electron mobility and can improve the current density by promoting electron movement from the active layer to the electrode. The trend of electron mobility is J SC and was well consistent with the trend of PCE.

[0191] Shunt resistance (R) from the JV curve in the dark state sh ) and series resistance (R s ) were obtained (Table 2). R of ZnO, PDIN-I, PDIN-Br, PDIN-BS, and PDIN-O based devices sh The values ​​are 497, 427, 434, 444 and 318 Ωcm 2 It is. R sh is related to the shunt leakage current, i.e., unwanted excess current at low bias, (V - J R s ) / R sh (V is the applied voltage, J is the current density) can be expressed as R sh If you reduce R, the leakage current increases and FF also decreases. sh The data were in good agreement with the FF of the device. The R of the device based on the PDIN derivative sh The value is R of ZnO-based devices shIt was lower than the value. R sh Reducing the Rs affects the FF and increases the current loss. The Rs values ​​of devices based on ZnO, PDIN-I, PDIN-Br, PDIN-BS, and PDIN-O are 3.86, 3.08, 3.72, 3.73, and 6.83 Ωcm. 2 The Rs values ​​of the device were PCE and J SC There was a close correlation with the trend, with the highest R in devices using PDIN-O as CIL. s Value and lowest R sh was observed, leading to low photovoltaic performance.

[0192] Effective voltage (V) eff ) and photocurrent density (J ph ), according to Figure 15a, which shows the relationship between log(V eff ) for log(J ph ) is low V eff In the domain, a linear relationship was observed and high V eff In the region, saturation began. The saturation photocurrent region (V) of devices based on ZnO, PDIN-I, PDIN-Br, PDIN-BS, and PDIN-O sat ) of V eff The values ​​are 0.22, 0.19, 0.25, 0.25, and 0.39 V, respectively. PDIN-O based devices have higher V compared to PDIN-I, PDIN-Br, and PDIN-BS based devices. sat , which is because PDIN-O provides a high energy barrier to the device.

[0193] Saturation current density (J sat ) conditions, the maximum exciton generation rate (G) of devices based on ZnO, PDIN-I, PDIN-Br, PDIN-BS and PDIN-O max ) are 1.20 x 10 each 27 , 1.28 x 10 27 , 1.19 x 10 27 , 1.1 x 1027 and 1.09 x 10 27 m 3 s -1 It was G max It did not show a significant change because it was affected by the absorbance of the active layer. High V eff Because photogenerated excitons dissociate into free charge carriers in J sat is limited by carrier transport and collection.

[0194] The exciton dissociation probabilities of devices based on ZnO, PDIN-I, PDIN-Br, PDIN-BS, and PDIN-O were 86.3%, 88.4%, 87.3%, 87.2%, and 78.6%, respectively (Fig. 15b). The experimental results suggest that the PDIN derivatives (PDIN-I, PDIN-Br, and PDIN-BS) induce an intermolecular electric field, thereby promoting exciton dissociation for additional charge generation at the interface contact between the intermediate layer and the active layer, thereby promoting charge increase. sc increased. J sc and light intensity (P light ) as shown in Fig. 15c, the α values ​​of devices based on ZnO, PDIN-I, PDIN-Br, PDIN-BS, and PDIN-O were 0.990, 0.981, 0.975, 0.983, and 0.971, respectively. These results indicate that bimolecular recombination is negligible or suppressed in the devices. V oc Wow P light In the graph of Fig. 15d, which illustrates the relationship between the n values ​​and the trap-assisted recombination, the slope (n value) explains the trap-assisted recombination. The n values ​​of the ZnO, PDIN-I, PDIN-Br, PDIN-BS, and PDIN-O-based devices are 1.173, 1.178, 1.212, 1.229, and 1.249, respectively, which indicate that the n values ​​are closer to 1 than 2, indicating that the charge recombination is effectively limited by trap-assisted recombination. In terms of photovoltaic parameters, the PDIN-I-based device has a J sc was the highest, but V ocwas slightly lower than that of ZnO, PDIN-Br, and PDIN-BS based devices.

[0195] The devices were exposed to AM 1.5G simulated illumination (100 mW cm) in a nitrogen atmosphere. -2 ) to evaluate the photostability of the device. The PDIN derivative showed photostability of approximately 85% of the initial PCE value even after 60 minutes of exposure, while the ZnO-based device showed low photostability (approximately 70%) after 60 minutes of exposure. In other words, the ZnO-based device showed faster performance degradation than the PDIN derivative-based device under the same conditions.

[0196] It is well known that the interfacial contact between the interlayer and the photoactive material can be degraded by ultraviolet (UV) light illumination and the presence of oxygen. To investigate whether there is a light-soaking issue due to trapped oxygen caused by applying various interlayers to the device, stability tests under UV light exposure and thermal stability tests were performed. The stability tests were performed in a nitrogen-filled glove box (oxygen concentration <1 ppm) and UV exposure was performed for a few seconds after the initial IV measurement and after the final IV measurement to determine whether the absence of UV during the aging process affects the device performance. A short UV exposure (5 s) was performed to avoid the formation of oxygen radicals that could degrade the absorber layer, and the stability tests were performed after annealing at room temperature and 85°C for 30 h (Figs. 16a and 16b). After the initial UV exposure at room temperature, all devices exhibited relatively small PCE loss due to a decrease in FF and V oc and J scThe decrease was negligible, indicating that oxygen-induced degradation and UV presence had less significant effects. Interestingly, the PDIN-I, PDIN-Br, and PDIN-BS based devices recovered their initial cell performances and all performance losses were recovered after the final UV irradiation. Nevertheless, the PCE decrease from the initial to the final PCE after the aging process was smaller for the PDIN derivative-based devices than for the reference device (PDIN-I = 2.58%, PDIN-Br = 3.37%, PDIN-BS = 3.33%, ZnO = 10.6%, PDIN-O = 12%). Since the PDIN layer is an effective oxygen barrier layer, the addition of the PDIN derivative as a CIL can increase the J sc The leakage current of PDIN-I was not changed, and this trend was well matched with the IV curve according to Fig. 13c, which indicates that PDIN-I is the most stable material because the leakage current of PDIN-I is smaller than that of other devices. The ZnO-based device showed higher leakage current due to trap states deeply localized inside the crystal structure due to chemical adsorption of oxygen, similar to the PDIN-Br and PDIN-BS-based devices. Trap-assisted recombination in the intermediate layer part is J sc In addition, V oc It is very important for device performance because it can reduce the recombination resistance. Both ZnO and PDIN derivative-based devices showed high recombination resistance values. Therefore, these devices showed high V even after degradation due to UV and oxygen. oc was able to maintain and improve voltage stability. In addition, a significant decrease in PCE was observed within 5 hours of thermal annealing. Since oxygen adsorption is an endothermic process, PCE loss accelerates at 85°C compared to the slow re-adsorption process at room temperature. The significant performance degradation of PDIN-O during the first 2 hours was attributed to the thermal annealing effect that occurred at 110°C during device fabrication.

[0197] To understand the carrier recombination and transport mechanism, electrochemical impedance spectroscopy (EIS) measurements were obtained. Figure 17 shows the recombination resistance (R) measured under dark conditions at 0 V. rec ) were shown. R of ZnO, PDIN-I, PDIN-Br, PDIN-BS, and PDIN-O based devices rec The values ​​were 447, 348, 358, 399, and 283 kΩ, respectively. R rec The size of the value is R sh and showed a decrease in the degree of interfacial recombination, similar to the trend of FF.

[0198]

[0199] <Example 4>

[0200] In this example, perylene diimide derivatives (PDIN-O, PDIN-N, and PDIN-OTs) were synthesized by introducing a quaternary ammonium ion and a counter anion (CA) to the perylene diimide side chain (Fig. 18), and an inverted polymer solar cell was manufactured using this as an electron transport layer material, and the cell characteristics, etc. were investigated.

[0201]

[0202] 1. Synthesis of PDIN

[0203] Dissolve 5 g of 3,4,9,10-perylenetetracarboxylic acid dianhydride in 100 ml of DMF, add 16 ml of N,N-dimethyl-1,3-propanediamine, and stir at 130°C for 12 hours. After cooling to room temperature, add 300 ml of THF, and remove the solution by filtration under reduced pressure from the formed precipitate. Then, wash three times with 300 ml of THF. Vacuum drying yielded a dark red solid in 94% yield.

[0204]

[0205] 2. Synthesis of PDIN-O, PDIN-N, and PDIN-OTs

[0206] 2.1 Synthesis of PDIN-O

[0207] 200 mg of PDIN was dissolved in 50 ml of ethanol, and 0.36 ml of H2O2 was added dropwise under an argon atmosphere. The mixture was stirred at room temperature for 30 minutes, and then at 60°C for 3 hours until the solution became transparent. After cooling to room temperature, the solution was removed under reduced pressure. The purple substance was purified by sequentially washing it three times with acetone and hexane, and then dried. A solid was obtained in a yield of 90%.

[0208] PDIN-O: 1 H NMR (400 MHz, MeOD, d, ppm): 7.22 (s, 4H, Ar), 6.79 (s, 4H, Ar), 3.80 (s, 4H, CH2(CH2)2NO(CH3)2), 3.22 (m, 4H, CH2NO(CH3)2), 3.18 (s,12H, CH3), 2.14 (m, 12H, CH2CH2NO(CH3)2). 13 C NMR (150 MHz, MeOD, d, ppm): 170.42, 163.52, 133.19, 130.60, 123.81, 128.21, 122.81, 122.36, 69.83, 58.80, 39.90, 23.86.

[0209]

[0210] 2.2 Synthesis of PDIN-N

[0211] A mixture of 39.2 g of perylene-3,4,9,10-tetracarboxylic dianhydride and 64.1 g of N,N-dimethyldipropylenetriamino in 300 ml of methanol was stirred at 60°C for 8 hours. After removing the solvent under reduced pressure, the mixture was washed with chloroform to obtain PDIN-N as a red solid in a yield of 70%.

[0212] 1H NMR (400 MHz, CDCl3), δ(ppm): 8.40 (dd,4H,J= 5.4, 0.5 Hz), 8.23 ​​(d, 4H,J= 5.4 Hz), 4.24 (t, 4H,J= 2.7 Hz), 2.75 (t, 4H,J= 4.3 Hz), 2.69 (t, 4H, 4.5 Hz), 2.33 (t, 4H,J= 5.8 Hz), 2.22 (s, 12H), 1.96(tt, 4H,J= 4.3, 2.7 Hz), 1.68 (m, 6H,J= 5.8, 4.5 Hz). 13 C NMR (400 MHz, CDCl3) δ (ppm): 162.8, 133.6, 130.6, 128.6, 125.4, 122.8, 122.5, 58.0, 48.3, 47.3, 45.5, 38.6, 28.4, 28.1.

[0213]

[0214] 2.3 Synthesis of PDIN-OTs

[0215] 2.56 g of PDIN was dissolved in 43.5 g of ethyl tosylate and 130 ml of methanol, and the mixture was reacted at 60°C for 12 hours under an argon atmosphere. The reaction mixture was cooled to room temperature and precipitated with chloroform through suction filtration. The precipitated solid was dried under vacuum to obtain a reddish-brown solid product in 81% yield.

[0216] 1 H NMR (DMSO-d6, 400MHz) δ (ppm): 8.61 (4H, dd,J= 5.4, 0.5 Hz), 8.39 (4H, d,J= 5.4 Hz), 3.83 (4H, t,J= 2.7 Hz), 2.63 (t,J= 4.3 Hz)), 2.57 (t,J= 4.5 Hz), 2.53 (t,J= 5.8 Hz), 2.47-2.68 (12H), 2.21 (12H, s), 1.89 (4H, tt,J= 4.3, 2.7 Hz), 1.54 (4H, tt,J= 5.8, 4.5 Hz). 13C NMR (DMSO-d6, 400 MHz) δ (ppm): 163.1, 134.7, 131.0, 128.9, 126.1, 124.0, 122.9, 64.3, 53.2, 37.4, 22.1.

[0217]

[0218] 3. Fabrication of organic solar cells (OSCs)

[0219] To fabricate an inverted OSC with a device structure of [ITO / SME / active layer (PM6:Y6BO, 138 nm) / MoO3 (3 nm) / Ag (100 nm)], the SME material was dissolved in MeOH, filtered through a 0.45 mm membrane filter, and spin-casted. The active layer was spin-casted with a mixture of PM6:Y6BO (1:1.2 with 0.5% (v / v) 1-chloronaphthalene (CN) in 1 mL of chlorobenzene) at 1000 rpm for 60 s. The active solution was filtered through a 0.45 mm membrane filter before spin-coating. The MoO3 layer and the Ag layer were deposited at a thickness of 2 × 10 -6 0.09 cm at Torr 2 Heat was continuously deposited through a shadow mask having a device area of ​​.

[0220]

[0221] 4. Fabrication of a single electron-only device

[0222] To investigate the electron mobility of the intermediate layer or ZnO layer, an electron-only device having the structure of [ITO / intermediate layer / Y6BO(38nm) / Al(100nm)] was fabricated.

[0223]

[0224] 5. Experimental example

[0225] Thermogravimetric analysis (TGA) results showed that PDIN-O started to decompose at 100°C, but other PDIN derivatives (PDIN-N and PDIN-OTs) showed excellent thermal stability up to 200°C.

[0226] To evaluate the photovoltaic properties of CBLs based on PDIN-O, PDIN-N, and PDIN-OTs, inverse-structured OSCs with the structure ITO / CBL / PM6:Y6BO / MoO3 / Ag were fabricated (Fig. 19a). 1.0 solar illumination (100 mWcm -2 ) and the current density-voltage (JV) curves of the device in the dark state are shown in Figs. 19b and c, and the device performance and photovoltaic parameters are listed in Table 4.

[0227]

[0228] [Table 4]

[0229]

[0230] a Calculated using the IPCE curve

[0231] b series resistor

[0232] c Shunt resistance in cancer state

[0233]

[0234] The PCEs of devices based on PDIN-O, PDIN-N, and PDIN-OTs were 12.5, 13.3, and 14.2%, respectively. These results demonstrate that PDIN-N and PDIN-OTs are useful as intermediate layer materials for inverted structure devices, and that modifying the counterion group overcomes the thermal stability issue of PDIN-O. PDIN-O-based devices exhibit low V oc , J sc The combination of PDIN-O and FF resulted in low PCE. The PDIN-O-based devices exhibited poor performance due to the work function mismatch between the active layer and ITO, and low charge extraction due to high contact resistance. The J of devices based on PDIN-O, PDIN-N, and PDIN-OTs sc The values ​​are 24.2, 24.8 and 25.7 mA cm -2Furthermore, the introduction of quaternary ammonium ions into the PDIN backbone can improve the device performance compared to PDIN-O based devices. 1.0 J obtained under sunlight illumination sc J calculated from the incident photocurrent efficiency (IPCE) sc was consistent with (Fig. 19d). PDIN-O can degrade device performance due to thermal degradation. The PCE of PDIN-O-based devices is lower than that of PDIN-N and PDIN-OTs-based devices. In such cases, large voltage losses in the OSC can occur due to the potential across the device. V of devices based on PDIN-O, PDIN-N, and PDIN-OTs oc were 0.78, 0.81 and 0.82 V, respectively. Low V oc It is caused by the transport characteristics of the device and trap-assisted recombination. The electron mobility was calculated by fabricating a single-electron device with the structure [ITO / CBL (5 nm) / Y6BO (38 nm) / Al (100 nm)], and the electron mobility of the devices based on PDIN-O, PDIN-N, and PDIN-OTs was 0.02 x 10 -4 , 0.05 x 10 -4 and 0.06 x 10 -4 cm -2 V -1 s -1 As can be seen in Fig. 20, the electron mobility of PDIN-N and PDIN-OTs based devices was higher than that of PDIN-O. The trend of electron mobility was J SC It matched well with the trend.

[0235] Series resistance (R s ) was calculated from the slope of the IV curve in the dark state. R of PDIN-O, PDIN-N, and PDIN-OTs-based devices s The values ​​are 6.83, 5.38 and 4.71 Ωcm, respectively. 2 It was. R of the device sThe value is correlated with the PCE trend of the device. R s The value was correlated with the resistive loss of the device. The improvement in FF was R s and shunt resistance (R sh ) can be confirmed. The smallest R s and the biggest R sh The values ​​explain that the charge carrier transport and collection ability is enhanced by CBL, which is in good agreement with the increase in FF and PCE. R sh describes the leakage current from the device, R sh The smaller the value, the better the current loss. R of devices based on PDIN-O, PDIN-N, and PDIN-OTs sh are 318, 382 and 420 kΩcm respectively. 2 It was.

[0236] To understand the charge transfer of the OSC, the effective voltage (V eff ) and photocurrent density (J ph ) was examined (Fig. 21a). log(V eff ) for log(J ph ) is low V eff In the domain, a linear relationship was observed and high V eff In the region, saturation of photocurrent began. The saturation photocurrent region (V) for PDIN-O, PDIN-N, and PDIN-OTs based devices sat ) in V eff The values ​​were 0.31, 0.29 and 0.28 V, respectively. The lower V sat is correlated with the rate of transition from the SCLC region to the saturation region. V sat The trend is J sc This is consistent with the change trend of PDIN-O. PDIN-O has a higher energy barrier and therefore has a higher V than PDIN-N and PDIN-OTs. sat It showed.

[0237] Saturation current density (J sat) conditions, the maximum exciton generation rate (G) of PDIN-O, PDIN-N, and PDIN-OTs based devices max ) values ​​are 1.09 × 10 28 , 1.14 × 10 28 and 1.14 × 10 28 m 3 s -1 It was G max It did not show a significant change because it was affected by the absorbance of the active layer. High V eff Because photogenerated excitons dissociate into free charge carriers in J sat is limited by carrier transport and collection.

[0238] Any V eff In J ph / J sat The exciton dissociation probabilities of each device calculated from the values ​​were 76.5, 81.2, and 81.6% for the devices based on PDIN-O, PDIN-N, and PDIN-OTs, respectively. J ph / J sat CBL (PDIN-N and PDIN-OTs) induces an intermolecular electric field and slightly increases exciton dissociation for additional charge generation at the interface contact between CBL and PM6:Y6BO, leading to J sc It is proven that it leads to improvement of J sc and light intensity (P light ) as shown in Fig. 21c, the α of devices based on PDIN-O, PDIN-N, and PDIN-OTs were 0.971, 0.973, and 0.974, respectively. These results indicate that bimolecular recombination is not a significant problem in the devices. V oc Wow P lightIn the graph of Fig. 21d, which illustrates the relationship, the slope (n value) explains trap-assisted recombination. The n values ​​of devices based on PDIN-O, PDIN-N, and PDIN-OTs were estimated to be 1.25, 1.37, and 1.30, respectively. This indicates that charge recombination was effectively suppressed by trap-assisted recombination.

[0239] Atomic force microscopy (AFM) analysis of the ITO modified with the intermediate layer showed that the root-mean-square roughness of PDIN-OTs was 2.329 nm, which was the lowest value compared to PDIN-N (2.549 nm) and PDIN-O (2.619 nm), and this result was consistent with the FF trend of the devices.

[0240] To investigate the aging behavior of PDIN-based devices, thermal stability tests were performed (Fig. 22). The thermal stability tests were performed inside a nitrogen-filled glove box to avoid further oxygen exposure. To overcome the light-soaking issue, newly fabricated devices were irradiated with UV light for 5 seconds, the current density-voltage (JV) curves of the devices were measured, and then the JV curves of the devices were measured again. After the first two JV measurements, the aging process was performed under thermal annealing conditions (85°C) for 30 hours. To determine whether UV had affected the results during the 30-hour aging, the devices were irradiated with UV LED again for 5 seconds, and then the final measurement was performed. All data presented were normalized for easy comparison and understanding. The PCE values ​​decreased dramatically within 5 hours after the initiation of thermal annealing. The PCE loss trend was also related to the decrease in FF due to the measurement at high temperatures, but the V oc and J scThe variation of PCE was observed to be small. A decrease in PCE from the initial to the final PCE was observed after the aging process. Nevertheless, the PCE decrease of the quaternary ammonium ion-based device was less than that of the PDIN-O-based device (PDIN-N = 26.3%, PDIN-OTs = 10.6%, PDIN-O = 34.4%). In addition, since the PDIN layer is an effective oxygen barrier layer, the addition of the PDIN derivative as a CIL can increase the J sc The significant performance degradation of PDIN-O during the first 2 hours was due to the thermal annealing effect that occurred at 110°C during device fabrication. Therefore, the PDIN-O-based devices were affected because PDIN-O degrades at approximately 100°C, consistent with the TGA results.

[0241] For each device, the recombination resistance (R) under dark conditions of 0 V rec ) was performed to measure the R of the devices based on PDIN-O, PDIN-N, and PDIN-OTs (Fig. 22). rec were 283, 290 and 333kΩ, respectively. As can be seen in Fig. 23, the increase in the size of the semicircle is R rec is correlated with the value. In EIS, the size of the semicircle is determined by the charge recombination value. High R rec The value indicates a decrease in interfacial recombination, which is R sh and follows the same trend as FF.

[0242]

[0243] The present invention is not limited to the above-described embodiments, but can be manufactured in a variety of different forms. Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

[0244] According to the present invention, a high-temperature process is not required when manufacturing a polymer solar cell, and a high-efficiency inverted-structure polymer solar cell can be realized.

Claims

1. A polymer solar cell comprising an electron transport layer containing an electrolyte composed of a diimide derivative compound between a cathode and an active layer.

2. In paragraph 1, A polymer solar cell characterized in that the skeleton of the diimide derivative compound is composed of naphthalene diimide.

3. In paragraph 2, The above diimide derivative compound is a polymer solar cell characterized by being represented by the following chemical formula 1: [Chemical Formula 1] .

4. In paragraph 2, The above diimide derivative compound is a polymer solar cell characterized by being represented by the following chemical formula 2: [Chemical Formula 2] .

5. In paragraph 2, The above diimide derivative compound is a polymer solar cell characterized by being represented by the following chemical formula 3: [Chemical Formula 3] (In the above chemical formula 3, OTs - Is lim).

6. In paragraph 2, The above diimide derivative compound is a polymer solar cell characterized by being represented by the following chemical formula 4: [Chemical Formula 4] .

7. In paragraph 1, A polymer solar cell characterized in that the skeleton of the diimide derivative compound is composed of perlyene diimide.

8. In paragraph 7, The above diimide derivative compound is a polymer solar cell characterized by being represented by the following chemical formula 5: [Chemical Formula 5] .

9. In paragraph 7, The above diimide derivative compound is a polymer solar cell characterized by being represented by the following chemical formula 6: [Chemical Formula 6] .

10. In paragraph 7, The above diimide derivative compound is a polymer solar cell characterized by being represented by the following chemical formula 7: [Chemical Formula 7] .

11. In paragraph 7, The above diimide derivative compound is a polymer solar cell characterized by being represented by the following chemical formula 8: [Chemical Formula 8] .

12. In paragraph 7, The above diimide derivative compound is a polymer solar cell characterized by being represented by the following chemical formula 9: [Chemical Formula 9] (In the above chemical formula 9, OTs - Is lim).

13. In any one of paragraphs 1 to 12, ITO substrate; An electron transport layer comprising an electrolyte composed of a diimide derivative compound; A donor composed of Poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione)](PM6) and An active layer comprising an acceptor composed of 2,2'-((2Z,2'Z)-((12,13-bis(2-butyloctyl)-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2'',3'':4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y6BO); A hole transport layer comprising molybdenum oxide (MoO3); and A polymer solar cell characterized by an inverted type in which silver (Ag) electrode layers are sequentially laminated.

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