Tribromide-Modified Wide-Bandgap Perovskite Inks for Iodine Defect Control
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Solution Overview
Problem
Current perovskite-silicon tandem solar cells face challenges such as short charge-carrier diffusion length, low power conversion efficiencies, and stability issues due to iodine interstitials leading to charge recombination and VOC deficits.
Innovation Solution
Incorporation of a tribromide salt in the perovskite ink solution to form a mixed halide perovskite film, which suppresses iodine interstitial formation and reduces charge recombination, enabling efficient charge collection in wide bandgap perovskite solar cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If perovskite solar cells use conventional ink solutions without tribromide salt, then the manufacturing process is simple, but the charge-carrier diffusion length is short and power conversion efficiency is low
Solution Approach 1:
The patent modifies the chemical composition parameters of the perovskite ink solution by introducing tribromide salt as an additive. This parameter change in the ink solution formulation enables the formation of mixed halide perovskite films with improved crystalline structure and reduced defects, thereby increasing charge-carrier diffusion length and power conversion efficiency without complicating the overall manufacturing process
Solution Approach 2:
The patent creates a composite material system by combining conventional perovskite precursors with tribromide salt in the ink solution. This composite approach results in mixed halide perovskite films that exhibit enhanced optoelectronic properties, including longer carrier diffusion lengths and higher efficiency, while maintaining the solution-processable nature of the material
2Reliability
If perovskite solar cells contain iodine interstitials, then the material synthesis is straightforward, but charge recombination increases and open-circuit voltage is reduced
Solution Approach 1:
The patent extracts and removes iodine interstitial defects from the perovskite crystal structure by using tribromide salt as a defect passivating agent. The tribromide salt selectively binds to and removes harmful iodine interstitials during the film formation process, thereby reducing charge recombination centers and improving open-circuit voltage without requiring complex post-processing steps
Solution Approach 2:
The patent converts the potentially harmful effect of iodine interstitials into a beneficial outcome by using tribromide salt to passivate these defects. The tribromide salt reacts with iodine interstitials to form stable complexes that eliminate the harmful defects, thereby transforming a source of degradation into an opportunity for improving device performance
3Use of energy by moving object
If perovskite solar cells are designed with wide bandgap for efficient light absorption, then the optical absorption is improved, but the charge-carrier diffusion length becomes shorter
Solution Approach 1:
The patent applies local quality improvement by creating mixed halide perovskite structures with spatially varying halide compositions. The tribromide salt creates localized regions with optimized crystal structure and reduced defect density specifically in areas where charge carriers are generated, thereby maintaining long diffusion lengths while preserving the wide bandgap properties for efficient light absorption
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
Enhances the efficiency of perovskite-silicon tandem solar cells by improving carrier diffusion length and reducing deep trap density, achieving efficiencies up to 28.6% with improved open-circuit voltage and fill factor.
Implementation Method 1
Defect engineering in wide bandgap perovskites for efficient and stable fully textured perovskite-silicon tandem solar cells
Implementation Method 2
suppresses iodine interstitial formation and reduces charge recombination
Implementation Method 3
Solar photovoltaic cells for terrestrial applications are typically made from inorganic semiconductor materials, e.g. Si, GaAs, CIGS (CuInGaSe), etc., which absorb a large percentage of solar radiation and convert it to electricity
Implementation Method 4
The perovskite active layer combines the promise of solution processing with the ability to tailor the band-gap through ion substitution. Associated with their photovoltaic performance, perovskite also exhibits high fractions of radiative recombination
Data Source
AI summary
Described herein are perovskite ink solutions comprising a composition of Formula I (APbI3-zBrz), a tribromide salt, and a solvent, wherein z is defined herein. Further described are perovskite films prepared using the ink solutions, methods for preparing the perovskite films, and use of the films in wide band gap single junction and tandem solar cells. As shown herein, solar cells fabricated using the perovskite films prepared from ink solutions comprising a tribromide salt achieve enhanced efficiency compared to solar cells comprising a perovskite film prepared without the tribromide salt.