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Halogen-Functionalized Hole Transport Materials with Strong Passivation Effects for Stable and Highly Efficient
Tong Bie1, Rui Li1, Xiang Gao2
1Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China.
ACS Nano
|August 16, 2024
Summary
New hole transport materials (HTMs) with halogen atoms improve quasi-two-dimensional perovskite solar cell (PSC) performance by reducing energy mismatch and passivating defects. This leads to higher efficiency and enhanced stability.
Area of Science:
- Materials Science
- Photovoltaics
- Chemical Engineering
Background:
- Perovskite solar cell (PSC) performance is significantly influenced by the interface between the hole transport material (HTM) and the perovskite layer.
- Optimizing this interface is crucial for efficient charge extraction and minimizing energy losses.
Purpose of the Study:
- To design and synthesize novel HTMs with triphenylamine-carbazole cores and halogenated end groups.
- To investigate the impact of these HTMs on the energy level alignment, defect passivation, and crystal quality in quasi-two-dimensional PSCs.
Main Methods:
- Synthesis of triphenylamine-carbazole-based HTMs with chlorine and bromine substituents.
- Characterization of HTM energy levels (HOMO) and their alignment with the perovskite layer.
- Fabrication and performance testing of quasi-two-dimensional PSCs incorporating the synthesized HTMs.
- Assessment of device stability under continuous illumination.
Main Results:
- Synthesized HTMs exhibited deeper highest occupied molecular orbital energy levels compared to commercial alternatives.
- Halogen bonding between HTMs and perovskite layer defects effectively passivated non-radiative recombination centers.
- Vertical crystal growth and improved quality of the perovskite layer were observed.
- Quasi-two-dimensional PSCs with chlorohexane-substituted HTMs achieved a power conversion efficiency of 21.07% and maintained 97.2% of initial efficiency after 1100 hours.
Conclusions:
- Novel halogenated HTMs enhance PSC performance through improved energy matching and defect passivation via halogen bonding.
- The developed HTMs promote high-quality perovskite crystal formation, leading to superior power conversion efficiency and operational stability.
