Application of an Organic Molecule in a Normal-Structure Perovskite Solar Cell

Abstract

The present invention belongs to the technical field of optoelectronic materials and devices, and relates to the application of an organic molecule in a normal perovskite solar cell. In order to eliminate the hysteresis factor in the perovskite solar cell, the organic molecule of the present invention contains both cations and anions, and the anions and cations can effectively passivate the defects of the perovskite film and improve the morphology of the perovskite film, thereby reducing the interfacial recombination of the device and increasing the carrier lifetime of the film. At the same time, due to the presence of cations, the hysteresis effect of the device itself can be effectively suppressed, thus realizing the controllable preparation of a highly efficient, stable and low-hysteresis perovskite solar cell.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic materials and devices, and particularly relates to the application of an organic molecule in a normal perovskite solar cell. Background Art

[0002] In the past decade, novel perovskite materials have attracted extensive attention from researchers. Without a doubt, perovskite has been widely used in various fields due to its high absorption coefficient, suitable bandgap, long exciton lifetime, and diffusion length, such as perovskite solar cells (PSCs), perovskite light-emitting diodes, and memristors. Among all these applications, PSCs show amazing potential. So far, the certified record power conversion efficiency (PCE) of single-junction devices has reached 25.7%. Early PSCs were based on titanium dioxide (TiO2) electron transport layer (ETL) materials. However, TiO2 is limited by its high-temperature manufacturing, poor ultraviolet (UV) stability, and inability to be used in flexible devices. Compared with TiO2, tin dioxide (SnO2) is a more suitable ETL material because it has excellent UV stability and is easy to manufacture at low temperatures. It is reported that a large number of high-performance PSCs with a PCE higher than 23% are based on SnO2 ETL. Nevertheless, there are still many problems to be solved, such as poor film crystallization, interface defects, and non-negligible hysteresis phenomena.

[0003] In addition to the poor film quality, interface non-radiative recombination caused by defects (halide vacancies, cation vacancies, and Pb-I antisites) also leads to device performance loss. Finally, hysteresis is also a stumbling block on the commercialization path of perovskite solar cells. Therefore, there is an urgent need to develop a multifunctional interface modification molecule to improve the film crystallization morphology, reduce interface non-radiative recombination, and hysteresis phenomena. Summary of the Invention

[0004] In view of this, in order to eliminate the hysteresis factor in perovskite solar cells, the present invention provides the application of cationic and anionic organic molecules in normal perovskite solar cells.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] An application of an organic molecule in a normal perovskite solar cell, wherein the organic molecule contains both a cation and an anion, and its structural formula is as follows:

[0007]

[0008] Wherein, A is H, Li, Na, K, Rb, or Cs.

[0009] Furthermore, the organic molecule is used as an interface modification molecule to modify the lower interface of the normal perovskite solar cell.

[0010] Furthermore, the normal perovskite solar cell is composed of a conductive base layer, an electron transport layer, a perovskite light absorption layer, a hole transport layer, and a metal back electrode layer stacked from bottom to top.

[0011] Furthermore, the modification of the lower interface of the normal perovskite solar cell by the organic molecule as an interface modification molecule is specifically as follows: The organic molecule is dissolved in a solvent, shaken, spin-coated on the electron transport layer, and then annealed at a high temperature.

[0012] Furthermore, the mass-volume ratio of the organic molecule to the solvent is 0.05 - 200 mg: 100 mL, the shaking time is 5 min - 48 h, the annealing temperature is 90 °C - 160 °C, and the annealing time is 5 min - 1 h.

[0013] Furthermore, the conductive base layer is one of ITO or FTO; the perovskite light absorption layer is an ABX3 perovskite light absorption layer, where A is CH3NH3 + or CH(NH2)2 + one of them, B is Pb 2+ , X is a halogen ion; the hole transport layer is at least one of 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly(3-hexylthiophene-2,5-diyl), cuprous thiocyanate, cuprous iodide, or nickel oxide; the metal back electrode layer is at least one of Au or Ag.

[0014] Furthermore, X is Cl - 、Br - or I - one of them.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The anions and cations in the present invention can effectively passivate the defects of the perovskite thin film, improve the morphology of the perovskite thin film, thereby reducing the interface recombination of the device and increasing the carrier lifetime of the thin film. At the same time, due to the presence of cations, the hysteresis effect of the device itself can be effectively suppressed. Thus, the controllable preparation of a highly efficient, stable, and low-hysteresis perovskite solar cell is realized.

[0017] 2. The perovskite solar cell prepared by using the organic molecule provided by the present invention has a maximum power conversion efficiency of up to 22.09%. After the unencapsulated device is kept at 50% humidity for 500 hours, its efficiency can still remain above 80% of the original efficiency. At the same time, the hysteresis factor is reduced from 0.055 to 0.025. The organic molecule in the present invention is of great significance for promoting the commercialization process of perovskite solar cells.

[0018] 3. After being modified by the organic molecule of the present invention, the energy level arrangement is more reasonable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the forward scan current-voltage curve graph of the perovskite solar cells in the comparative example and Example 1;

[0020] Figure 2 It is the statistical graph of the hysteresis factor of the perovskite solar cells in the comparative example and Example 1;

[0021] Figure 3 It is the statistical graph of the humidity stability of the perovskite solar cells in the comparative example and Example 1;

[0022] Figure 4 It is the energy level arrangement diagram of the comparative example and Example 1;

[0023] Figure 5 It is the forward scan current-voltage curve graph of the perovskite solar cell in Example 2;

[0024] Figure 6 It is the forward scan current-voltage curve graph of the perovskite solar cell in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0026] Comparative Example

[0027] The method for preparing a perovskite solar cell includes the following steps:

[0028] (1) The ITO conductive substrate is ultrasonically treated with detergent, deionized water, and absolute ethanol for 30 minutes in sequence, then dried with nitrogen, and then treated with ultraviolet ozone for 30 minutes and cooled for standby;

[0029] (2) Add pure water (V SnO2 :V H2O = 1:4) to the SnO2 nanoparticle dispersion with a mass fraction of 15%, mix well and then drop it onto the ITO conductive substrate treated in step (1). Then spin-coat it at a speed of 4000 rpm for 30 s, and then anneal it at 150 °C for 30 min to obtain the electron transport layer. Subsequently, perform ultraviolet ozone irradiation treatment on the electron transport layer for 10 min;

[0030] (3) Dissolve FAI (248 mg), PbBr2 (8.5 mg), RbI (6.6 mg), MACl (35.0 mg), PbI2 (682.7 mg), CsI (19.7 mg) and PbCl2 (12.7 mg) in a mixed solution of DMF and DMSO (V DMF :V DMSO = 4:1), shake for 5 min, and then drop the perovskite solution onto the electron transport layer prepared in step (2). Spin-coat it at a speed of 4000 rpm for 30 s, and then anneal it at 130 °C for 28 min. Among them, 16 s before the end of the perovskite solution spin-coating, 80 μL of chlorobenzene is dropped within 2 s to obtain the perovskite light-absorbing layer;

[0031] (4) Dissolve 72.3 mg of 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD) in 1 mL of chlorobenzene, and add 29 μL of TBP and 18 μL of Li-TFSI (concentration: 520 mg / mL, solvent: anhydrous acetonitrile). Mix well and then drop it onto the perovskite light-absorbing layer prepared in step (3). Spin-coat it at a speed of 3000 rpm for 30 s to obtain the hole transport layer;

[0032] (5) Under high vacuum (10 -4 Pa), evaporate an Au electrode with a thickness of 80 nm on the hole transport layer prepared in step (4) by thermal evaporation.

[0033] Example 1

[0034] Method for preparing a perovskite solar cell:

[0035] The difference from the comparative example is that the following operation is added between step (2) and step (3):

[0036] Dissolve organic molecule A in water to prepare a solution with a concentration of 0.75 mg / mL, shake for 20 min, and then spin-coat the solution onto the electron transport layer at a speed of 5000 rpm and anneal it at 150 °C for 5 min.

[0037]

[0038] Figure 1 To compare the current-voltage scan curves of the perovskite solar cells in the comparative example and Example 1, and obtain the photovoltaic parameters of the two types of cells based on this graph. The results are shown in Table 1. From Figure 1 Table 1, it can be seen that the efficiency of the perovskite solar cell in Example 1 has been significantly improved.

[0039] Table 1

[0040]

[0041] Figure 2 To compare the statistical chart of the hysteresis factor of the perovskite solar cells in the comparative example and Example 1, it can be seen that the hysteresis factor of the perovskite solar cell in Example 1 has been significantly reduced.

[0042] Figure 3 To compare the statistical chart of the humidity stability of the perovskite solar cells in the comparative example and Example 1, it can be seen that the perovskite solar cell in Example 1 exhibits excellent humidity stability.

[0043] Figure 4 To compare the energy level arrangement diagrams of the comparative example and Example 1, it can be seen that after the molecular modification in Example 1, the energy level of the electron transport layer changes from -3.89 eV in the comparative example to -3.80 eV. This change makes the energy level difference between the electron transport layer and the perovskite light-absorbing layer smaller, which is beneficial for more carriers to transfer from the perovskite light-absorbing layer to the electron transport layer.

[0044] Example 2

[0045] The difference from Example 1 is that the cation in the organic molecule is Cs, with a concentration of 0.0005 mg / mL, shaken for 5 min, annealing temperature of 160 °C, and annealing time of 10 min.

[0046] Figure 5 For the forward current-voltage scan curve of the perovskite solar cell in Example 2, it can be seen that the efficiency of this cell is 20.95%, and compared with the efficiency of the cell in the comparative example (20.06%), the device efficiency has been significantly improved.

[0047] Example 3

[0048] The difference from Example 1 is that the cation of the organic molecule is Na, with a concentration of 2 mg / mL, shaken for 48 h, annealing temperature of 90 °C, and annealing time of 1 h.

[0049] Figure 6It is the forward current-voltage curve graph of the perovskite solar cell in Example 3. It can be seen that the efficiency of this cell is 21.05%. Compared with the efficiency of the cell in the comparative example (20.06%), the device efficiency has been significantly improved.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered within the scope of the claims of the present invention.

Claims

1. Application of an organic molecule in a normal perovskite solar cell, characterized in that, The organic molecule contains both a cation and an anion, and its structural formula is as follows: ； Wherein, A is H, Li, Na, K, Rb or Cs; The organic molecule is used as an interfacial modification molecule to modify the lower interface of a normal perovskite solar cell.

2. Use of an organic molecule in a normal perovskite solar cell according to claim 1, characterized in that The normal perovskite solar cell is composed of a conductive substrate layer, an electron transport layer, a perovskite light absorption layer, a hole transport layer and a metal back electrode layer stacked from bottom to top.

3. The application of an organic molecule in a normal perovskite solar cell according to claim 2, wherein The organic molecule is used as an interfacial modification molecule to modify the lower interface of a normal perovskite solar cell specifically as follows: The organic molecule is dissolved in a solvent, shaken, spin-coated on the electron transport layer, and then annealed at a high temperature.

4. The application of an organic molecule in a normal perovskite solar cell according to claim 3, wherein The mass-volume ratio of the organic molecule to the solvent is 0.05~200 mg: 100 mL, the shaking time is 5 min~48 h, the annealing temperature is 90°C~160°C, and the annealing time is 5 min~1 h.

5. The application of an organic molecule in a normal perovskite solar cell according to claim 2, wherein The conductive base layer is one of ITO or FTO; the perovskite light-absorbing layer is an ABX3 perovskite light-absorbing layer, where A is CH3NH3 + or CH(NH2)2 + one of them, B is Pb 2+ , X is a halide ion; the hole transport layer is at least one of 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], poly(3-hexylthiophene-2,5-diyl), cuprous thiocyanate, cuprous iodide or nickel oxide; the metal back electrode layer is at least one of Au or Ag.

6. The application of an organic molecule in a normal-structure perovskite solar cell according to claim 5, wherein X is Cl - , Br - or I - and is one of them.

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