Crosslinked Polymer Passivation for Perovskite Film Grain Boundaries
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Solution Overview
Problem
Perovskite optoelectronic devices face challenges due to crystal grain boundary defects and precipitation issues in the precursor solutions when using linear polymers, which affect the quality and stability of the films and devices.
Innovation Solution
A method involving the in-situ reaction of first and second monomers to form a crosslinked polymer, which is combined with perovskite crystal grains at the grain boundaries, avoiding precipitation and enhancing the film's hydrothermal and mechanical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear polymers are added as additives to perovskite precursor solution, then crystal grain boundaries can be protected and defects passivated, but precipitates form in the perovskite precursors which is detrimental to subsequent solution processing
Solution Approach 1:
The patent changes the chemical structure parameters of the additive by using crosslinkable monomers instead of linear polymers. The monomers have specific functional groups and molecular weights that allow them to dissolve in the precursor solution and subsequently crosslink upon heating, transforming from a soluble state to an insoluble network state that protects grain boundaries without causing precipitation during processing
Solution Approach 2:
The patent applies preliminary action by adding the crosslinkable monomers to the precursor solution before perovskite film formation. The monomers are pre-positioned at the crystal grain boundaries during film deposition, and then crosslinking is triggered by heating treatment after the perovskite crystals have formed, ensuring both solution processability and grain boundary protection
2Reliability
If small molecular compounds are used as additives, then crystal grain boundaries can be protected, but the passivation effect is insufficient compared to polymer additives
Solution Approach 1:
The patent creates a composite structure where crosslinkable monomers form a polymer network embedded within the perovskite crystal grain boundaries. This composite of organic monomers and inorganic perovskite crystals provides enhanced defect passivation compared to small molecular compounds alone, while maintaining the benefits of solution processing
Solution Approach 2:
The patent segments the additive function into two distinct stages: first, the monomers dissolve and distribute in the precursor solution; second, upon heating, they crosslink to form a segmented network structure specifically at the grain boundaries. This segmentation allows the additive to provide both solution processability and effective passivation
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 crosslinked polymer effectively passivates defects, improves charge transfer efficiency, and increases the stability and optoelectronic properties of the perovskite film, preventing ion migration and enhancing the device's performance and durability.
Implementation Method 1
the first monomer and the second monomer are reacted in situ to form a first polymer
Implementation Method 2
the perovskite precursor solution forms perovskite crystal grains
Implementation Method 3
the first polymer is combined with the perovskite crystal grains and concentrated at a crystal grain boundary of the perovskite crystal grains
Data Source
AI summary
A perovskite film, method of preparing thereof, and an optoelectronic device are provided. They are prepared by steps including preparing a mixture containing a first monomer and a second monomer which can be crosslinked in situ; performing an annealing process, and the first monomer and the second monomer are reacted in situ to form a first polymer which combines with the perovskite crystal grains formed by the perovskite precursor and is concentrated at a crystal grain boundary of the perovskite crystal grains to passivate the perovskite crystal grain defects, and then a perovskite film is formed by curing.