Efficient luminescent solar cells based on tailored mixed-cation perovskites

Area of Science:

• Materials Science
• Renewable Energy
• Solid-State Physics

Background:

• Metal halide perovskites are promising for photovoltaics due to their tunable properties.
• Achieving high efficiency and good stability in perovskite solar cells remains a key challenge.
• Electroluminescence is a critical metric for assessing the quality of photovoltaic materials.

Purpose of the Study:

• To develop a high-efficiency perovskite solar cell with enhanced electroluminescence.
• To investigate the role of precursor composition on device performance.
• To understand the mechanisms behind improved charge carrier dynamics.

Main Methods:

• Fabrication of perovskite films via a single-step solution process using formamidinium (FA) and methylammonium (MA) based precursors.
• Characterization of perovskite solar cells using current-voltage measurements under AM 1.5 sunlight.
• Analysis of film composition using Rietveld analysis of X-ray diffraction data.
• Investigation of charge carrier dynamics using time-resolved photoluminescence decay measurements.

Main Results:

• A maximum power conversion efficiency of 20.8% was achieved for perovskite solar cells.
• Films with a PbI2/FAI molar ratio of 1.05 showed optimal performance.
• Excess PbI2 (approx. 3 wt%) in the film was found to suppress nonradiative charge carrier recombination.
• External electroluminescence quantum efficiency reached approximately 0.5%, a record for perovskite photovoltaics.
• An open-circuit photovoltage of 1.18 V was recorded.

Conclusions:

• Single-step solution-processed perovskite solar cells can achieve high power conversion efficiencies.
• Controlled excess of PbI2 is crucial for suppressing recombination and enhancing electroluminescence.
• These findings position perovskite photovoltaics as a competitive alternative to silicon solar cells.