Perovskite Solar Cell Surface Chemistry to Suppress Recombination
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Solution Overview
Problem
Existing perovskite solar cells using multiple divalent cations in the B site of the perovskite compound face challenges in achieving high photoelectric conversion efficiency due to recombination and material deterioration, with efficiencies dropping to half or less when compared to single cation systems.
Innovation Solution
Incorporating a first and second metal element with respective amine materials having two or more carbon atoms into the perovskite compound's photoelectric conversion layer, forming a surface region with these compounds to suppress recombination and deterioration, and optionally including hole and electron transport layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a perovskite compound containing multiple divalent cations (e.g., tin and lead) is used in the photoelectric conversion layer, then the band gap can be reduced to less than or equal to 1.3 eV to extend light absorption, but the photoelectric conversion efficiency deteriorates due to recombination and material deterioration
Solution Approach 1:
The photoelectric conversion layer is segmented into multiple functional components: a perovskite compound containing multiple divalent cations (tin and lead) for broad light absorption, and separate electron transport and hole transport layers to spatially separate charge carriers. This segmentation prevents recombination by directing electrons and holes to different destinations, thereby maintaining high photoelectric conversion efficiency despite the use of multiple cations.
Solution Approach 2:
Electron transport materials and hole transport materials are introduced as intermediary substances between the perovskite compound and the electrodes. These intermediaries facilitate selective charge carrier transport while preventing direct recombination at interfaces. The electron transport material mediates electron extraction, while the hole transport material mediates hole extraction, thereby protecting the multi-cation perovskite from degradation and maintaining efficiency.
2Adaptability or versatility
If a perovskite compound with multiple divalent cations is used, then the light absorption range can be extended, but material deterioration occurs resulting in efficiency less than half of single cation cells
Solution Approach 1:
The electron transport material and hole transport material serve as protective intermediary layers between the multi-cation perovskite compound and the external environment. These intermediaries prevent direct exposure to moisture, oxygen, and other degrading factors, thereby extending the operational lifetime of the material while preserving its extended light absorption capabilities.
Solution Approach 2:
The photoelectric conversion layer is constructed as a composite material system combining the multi-cation perovskite compound with electron transport materials and hole transport materials. This composite structure leverages the complementary properties of each component: the perovskite provides broad light absorption, while the transport materials provide stability and protective functions, resulting in a system that maintains both extended absorption range and improved durability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed configuration enhances photoelectric conversion efficiency by mitigating recombination and material degradation, resulting in improved performance compared to cells without amine materials, with efficiencies exceeding 19.74%.
Implementation Method 1
a perovskite compound containing a first metal element and a second metal element... as a photoelectric conversion material
Data Source
AI summary
A solar cell according to the present disclosure includes a first electrode, a photoelectric conversion layer, and a second electrode in this order. The photoelectric conversion layer comprises a perovskite compound comprising a first metal element and a second metal element, a first compound comprising the first metal element and a first amine material having two or more carbon atoms, and a second compound comprising the second metal element and a second amine material having two or more carbon atoms.