Search

EP-4739049-A1 - SEMITRANSPARENT THIN FILM SOLAR CELL AND PREPARATION METHOD THEREOF

EP4739049A1EP 4739049 A1EP4739049 A1EP 4739049A1EP-4739049-A1

Abstract

Disclosed is a customized semitransparent thin film solar cell comprising a substrate layer comprising a transparent conductive oxide on top of a glass layer, a double electron transport layer comprising a first electron transport layer and a second electron transport layer deposited by ultrasonic spray pyrolysis (USP), an absorber layer deposited by USP, and a back contact layer.

Inventors

  • KRUNKS, MALLE
  • Spalatu, Nicolae
  • KATERSKI, ATANAS
  • Asare, Ernest
  • Saleh, Hadeer
  • OJA ACIK, ILONA

Assignees

  • Tallinn University of Technology

Dates

Publication Date
20260506
Application Date
20241104

Claims (15)

  1. A semitransparent thin film solar cell comprising following stacked layers: - a substrate layer comprising a transparent conductive oxide (002), TCO, on top of a glass layer (004); - a double electron transport layer (006), ETL, comprising - a first electron transport layer (008), ETL1, and - a second electron transport layer (010), ETL2, deposited by ultrasonic spray pyrolysis, USP; - an absorber layer (012) deposited by ultrasonic spray pyrolysis, USP; - a back contact layer (014).
  2. A semitransparent thin film solar cell according to claim 1, further comprising a hole transport layer (016), HTL, between the absorber layer and the back contact layer.
  3. A semitransparent thin film solar cell according to claim 2, wherein the absorber layer (012) thickness is from 40 nm up to 200 nm.
  4. A semitransparent thin film solar cell according to any of the preceding claims, wherein at least one of the first electron transport layer (008), ETL1, and the second electron transport layer (010), ETL2, comprises at least one of selected materials from: TiO 2 , ZnO, SnO 2 , ZrO 2 , ZnS, Zn(O,S), Sb-doped ZnO.
  5. A semitransparent thin film solar cell according to any of the preceding claims, wherein the absorber layer (012) comprises at least one of selected materials from: Sb 2 S 3 , AgBiS 2 , CuSbS 2 , CuBiS 2 , AgSbS 2 , Bi 2 S 3 , Sb 2 (S,Se) 3 , Sb 2 Se 3 .
  6. A semitransparent thin film solar cell according to any of the preceding claims, wherein the hole transport layer (016), HTL, comprises at least one of selected from: P3HT, NiOx, Spiro-OmeTAD, MnS, MoOs, small organic molecules.
  7. A semitransparent thin film solar cell according to any of the preceding claims, wherein the back contact layer (014) comprises at least one of selected from: Au, Ag, Ag nanowires, C.
  8. A method of preparing semitransparent thin film solar cell, the method comprising: - cutting a glass substrate comprising a transparent conductive oxide layer (002), TCO, on top of a glass; - cleaning the substrate layer; - producing a double electron transport layer (006), ETL, on top of the substrate TCO layer by - depositing a first electron transport layer (008), ETL1, and - depositing a second electron transport layer (010), ETL2, by ultrasonic spray pyrolysis, USP; - depositing an absorber layer (012) by ultrasonic spray pyrolysis, USP; - annealing the cleaned substrate layer, the double electron transport layer (006) and the absorber layer (012) at a temperature range from 260 °C up to 310 °C in nitrogen flow for at least 2 minutes up to 20 minutes; - adding a back contact layer (014).
  9. A method according to claim 8, wherein depositing the absorber layer (012) by ultrasonic spray pyrolysis, USP, is carried out with following conditions: - at a temperature range from 170 °C up to 210 °C for at least 20 minutes up to 120 minutes, - depositing a precursor solution at a rate ranging from 2.0 ml/min up to 4.8 ml/min with a carrier gas at a rate ranging from 2 L/min up to of 5 L/min and a director gas from 0.2 L/min to 1 L/min form Sb 2 S 3 , wherein the precursor solution comprises an antimony chloride (SbCl 3 ) and a thiourea (SCN 2 H 4 , tu) with a molar ratio ranging from 1:2.5 up to 1:9 dissolved in methanol, and wherein the antimony chloride concentration is ranging from 15 mM up to 65 mM.
  10. A method according to claims 7 or 8, wherein - depositing the first electron transport layer (008), ETL1, comprises depositing titanium(IV)isoproxide and acetylacetone on the transparent conductive glass layer to form the first electron transport layer, wherein a molar ratio of titanium(IV)isoproxide and acetylacetone is ranging from 1:1 to 1:4 and temperature used during ultrasonic spray pyrolysis is ranging from 300 °C up to 500 °C; - annealing the first electron transport layer (008) at temperature range from 400 °C up to 500 °C for at least 30 minutes up to 120 minutes, and - depositing the second electron transport layer (010), ETL2, comprises spraying a solution onto the first electron transport layer (008) at temperature of 400 °C up to 500 °C to form a second electron transparent layer, wherein the solution comprises Zn(CH 3 CO 2 ) 2 in deionized water and isopropyl alcohol mixture (2:3 by volume) with a Zn(CH 3 CO 2 ) 2 concentration range from 1·10 -4 mol/l up to 9·10 -4 mol/l.
  11. A method according to any of the claims 8-10, further comprising producing a hole transport layer (016), HTL, between the absorber layer (012) and the back contact layer (014), wherein the hole transport layer (016) is produced as, spiro-OMETAD, Poly(3-hexylthiophene-2,5-diyl), P3HT, MoOx layer, NiOx layer, MnS layer or NiOx nanoparticle layer.
  12. A method according to claim 11, wherein producing the Poly(3-hexylthiophene-2,5-diyl), P3HT, layer comprises following steps: - spin coating a Poly(3-hexylthiophene-2,5-diyl), P3HT, onto the absorber layer at speed of 3000 rpm for 0.33 minutes to form thin film layers, wherein the Poly(3-hexylthiophene-2,5-diyl) is dissolved in chlorobenzene with concentration of 1 wt%, - heating the formed thin film layers in an inert atmosphere at 150 °C for 5 min.
  13. A method according to any of the claims 8-12, wherein adding the back contact layer (014) is carried out by depositing at least one of: Au, Ag; and wherein depositing is carried out using vacuum evaporation technique or Ag nanowire.
  14. A method according to any of the claims from 8-13, wherein depositing the absorber layer (012) comprising Sb 2 S 3 by ultrasonic spray pyrolysis, USP, is carried out: - at a nebulization frequency of ranging from 1 MHz up to 2 MHz, and - with a power of ranging from 30 W up to 300 W.
  15. A method according to any of the claims from 8-14, wherein spraying is carried at least 30 minutes up to 90 minutes at spraying rate ranging from 2 ml/min up to 5 ml/min using a carrier gas with the carrier gas rate ranging from 3 L/min up to 10 L/min and a director gas with the director gas rate ranging from 0.2 L/min up to 1 L/min.

Description

TECHNICAL FIELD The present disclosure relates to semitransparent thin film solar cells. It further covers methods for preparing semitransparent thin film solar cells, ensuring both transparency and efficiency. BACKGROUND Significant progress has been achieved in the development of various solar cell technologies, including silicon solar cells, organic solar cells, dye sensitized solar cells, Quantum dots solar cells, perovskite solar cells and chalcogenide solar cells. Furthermore, there is a need for semitransparent solar cells, offering the dual benefits of energy generation and transparency, which makes them suitable for integration. Semitransparent solar cells, while promising for applications like building-integrated photovoltaics and transparent displays, face several significant drawbacks. Traditional solar cells, such as crystalline silicon-based cells, are designed to maximize light absorption to convert sunlight into electrical energy efficiently and therefore these cells are opaque and cannot be used in applications requiring transparency. Additionally, many semitransparent technologies, such as organic photovoltaics and perovskites, suffer from limited durability and stability, particularly when exposed to environmental factors like UV radiation and moisture. Moreover, achieving high transparency often results in unwanted color tints, which can be aesthetically undesirable for certain applications. Lastly, the manufacturing processes for semitransparent cells tend to be more complex and expensive, making large-scale production economically challenging. Typical semitransparent solar cell has the following structure: substrate/transparent conductive oxide/electron transport layer/absorber layer/hole transport layer/back contact. Out of these layers, electron transport layer (ETL) presents several challenges that need to be addressed for optimal performance. One of the key issues is the trade-off between transparency and conductivity, as many ETL materials that offer good electron transport properties tend to be opaque, which can compromise the transparency of the solar cell. Additionally, poor energy level alignment between the ETL and the active layer can lead to inefficient charge extraction and increased recombination, reducing overall efficiency. Surface defects and trap states in the ETL can further hinder electron mobility and lead to performance degradation over time. Finally, achieving an optimal thickness for the ETL is crucial-too thin can result in poor charge transport, while too thick can introduce optical losses and increase resistance. Addressing these issues is essential for improving the efficiency, stability, and transparency of semitransparent solar cells. In addition, for preparation of absorber layer, most widely employed techniques for the deposition of an absorber layer are spin-coating, hydrothermal growth and chemical bath deposition. The highest efficiencies are obtained by these techniques, comprising absorber with thickness approximately higher than 250 nm. However, such absorber thickness compromise the development of semi-transparency concept. Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with making semitransparent solar cells. SUMMARY The aim of the present disclosure is to provide a semitransparent thin film solar cell which has a customizable semitransparency and a method to produce thin film solar cell capable of enhanced power conversion efficiency under low light illumination conditions and compatible with powering IoT eco-systems. The aim of the disclosure is achieved by a system for producing a semitransparent thin film solar cell, as defined in the appended independent claims to which reference is made to. Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative embodiments constructed in conjunction with the appended claims that follow. Throughout the description and claims of this specification, the words "comprise", "include", "have", and "contain" and variations of these words, for example "comprising" and "comprises", mean "including but not limited to", and do not exclude other components, items, integers or steps not explicitly disclosed also to be present. Moreover, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. BRIEF DESCRIPTION OF THE DRAWINGS The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclo