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Additive‐Free Oxidized Spiro‐MeOTAD Hole Transport Layer Significantly Improves Thermal Solar Cell Stability (in EN)

Journal Article · · Advanced Energy Materials
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  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Active Surfaces, Somerville, MA (United States)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Eidgenoessische Technische Hochschule (ETH), Zurich (Switzerland)
  4. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Paderborn Univ. (Germany)
+ Show Author Affiliations
Perovskite solar cells are among the most promising new solar technologies, already surpassing polycrystalline silicon solar cell efficiencies. The stability of the highest efficiency devices at elevated temperature is, however, poor. These cells typically use Spiro-MeOTAD as the hole transporting layer. It is generally believed that additives, required for enhancing electrical conductivity and optimizing energy level alignment, are responsible for the reduced stability—inferring that Spiro-MeOTAD based hole transporting layers are intrinsically unstable. Here, a reliable noble metal free synthesis of Spiro-MeOTAD (bis(trifluoromethane)sulfonimide)4 is presented which is used as the oxidizing agent. No additives are added to the partially oxidized Spiro-MeOTAD hole-transporting layer. Device efficiencies up to 24.2% are achieved. Electrical conductivity is largely developed by the first 1% oxidation. Further oxidation shifts the energy levels away from the vacuum level, which allows tuning of the energy level alignment without the use of additives—contradicting the current understanding of this system. Without additives, devices demonstrate significant improvement in stability at elevated temperatures up to 85 °C under one sun over 1400 h continuous illumination. The remaining degradation is pinpointed to ion migration and reactions in the perovskite layer which may be further suppressed with compositional engineering and adequate ion barrier layers.
Research Organization:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Organization:
Swiss National Science Foundation (SNSF); USDOE; USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
Grant/Contract Number:
EE0009512; SC0021650
OSTI ID:
2429740
Alternate ID(s):
OSTI ID: 2429741
OSTI ID: 2575810
Journal Information:
Advanced Energy Materials, Journal Name: Advanced Energy Materials Journal Issue: 31 Vol. 14; ISSN 1614-6840; ISSN 1614-6832
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
EN

References (10)

LiTFSI‐Free Spiro‐OMeTAD‐Based Perovskite Solar Cells with Power Conversion Efficiencies Exceeding 19% journal July 2019
Oxidized Spiro-OMeTAD: Investigation of Stability in Contact with Various Perovskite Compositions journal December 2021
Oxidation of Spiro-OMeTAD in High-Efficiency Perovskite Solar Cells journal July 2022
Effect of Selective Contacts on the Thermal Stability of Perovskite Solar Cells journal February 2017
Mechanical Reliability of Fullerene/Tin Oxide Interfaces in Monolithic Perovskite/Silicon Tandem Cells journal January 2022
Enhancing the Hole-Conductivity of Spiro-OMeTAD without Oxygen or Lithium Salts by Using Spiro(TFSI) 2 in Perovskite and Dye-Sensitized Solar Cells journal July 2014
Improving the stability of inverted perovskite solar cells towards commercialization journal September 2022
Single crystal structure and opto-electronic properties of oxidized Spiro-OMeTAD journal January 2020
Lithium salts as “redox active” p-type dopants for organic semiconductors and their impact in solid-state dye-sensitized solar cells journal January 2013
Accelerated aging of all-inorganic, interface-stabilized perovskite solar cells journal July 2022

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Related Subjects

Chemistry
Energy & Fuels
Materials Science
Physics
TFSI
perovskite solar cell
spiro-MeOTAD
thermal stability