Junction Quality of SnO2-Based Perovskite Solar Cells Investigated by Nanometer-Scale Electrical Potential Profiling
[2];
[5];
[2];
- National Renewable Energy Lab. (NREL), Golden, CO (United States); Colorado School of Mines, Golden, CO (United States)
- The Univ. of Toledo, Toledo, OH (United States)
- Colorado School of Mines, Golden, CO (United States)
- Chinese Academy of Science, Zhejiang Province (China)
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
Electron-selective layers (ESLs) and hole-selective layers (HSLs) are critical in high-efficiency organic-inorganic lead halide perovskite (PS) solar cells for charge-carrier transport, separation, and collection. We developed a procedure to assess the quality of the ESL/PS junction by measuring potential distribution on cross-section of SnO2-based perovskite solar cells using Kelvin probe force microscopy. Using the potential profiling, we compared three types of cells made of different ESLs but otherwise having identical device structure: cells with PS deposited directly on bare fluorine-doped SnO2 (FTO)-coated glass; cells with an intrinsic SnO2 thin layer on the top of FTO as an effective ESL; and cells with the SnO2 ESL and adding a self-assembled monolayer (SAM) of fullerene. The results reveal two major potential drops or electric fields at the ESL/PS and PS/HSL interfaces. The electric-field ratio between the ESL/PS and PS/HSL interfaces increased in devices as follows: FTO < SnO2-ESL < SnO2+SAM; this sequence explains the improvements of fill factor (FF) and open-circuit voltage (Voc). The improvement of FF from the FTO to SnO2-ESL cells may result from the reduction in voltage lose at the PS/HSL back interface and the improvement of Voc from the prevention of hole recombination at the ESL/PS front interface. The further improvements with adding a SAM is caused by the defect passivation at the ESL/PS interface, and hence, improvement of the junction quality. Furthermore, these nanoelectrical findings suggest possibilities for improving the device performance by further optimizing the SnO2-based ESL material quality and the ESL/PS interface.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- Grant/Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1404880
- Report Number(s):
- NREL/JA-5K00-67770
- Journal Information:
- ACS Applied Materials and Interfaces, Vol. 9, Issue 44; ISSN 1944-8244
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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