Dynamic Urea Bond Passivators for Perovskite Solar Cell Stability
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Solution Overview
Problem
Poly-crystalline perovskites are sensitive to environmental factors such as hygroscopic dopants and atmospheric moisture, leading to instability and difficulties in controlling trap density for reproducible device performance and stability in solar cells.
Innovation Solution
A dynamic hindered urea bond-based Lewis acid-base (HUBLA) material is introduced, which can absorb moisture and release Lewis bases to heal defects, thereby improving the performance and stability of perovskite solar cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional passivation strategies are used, then defect suppression is achieved, but device stability under ambient conditions deteriorates
Solution Approach 1:
The passivation layer contains latent Lewis base sites that are initially dormant. Upon exposure to moisture, these sites are activated and automatically bind to Pb2+ ions at defect sites, enabling the material to self-heal without external intervention. This self-activating mechanism ensures long-term stability while maintaining effectiveness.
Solution Approach 2:
The passivation layer is pre-designed with hidden functional groups (Lewis bases) that are not yet active during initial device operation. These groups are prepared in advance to become active only when needed, upon moisture exposure, providing proactive protection against environmental degradation.
2Reliability
If excess lead iodide is doped to suppress charge recombination, then open-circuit voltage is improved, but sensitivity to atmospheric moisture increases
Solution Approach 1:
The passivation layer acts as an intermediary barrier between the moisture-sensitive perovskite bulk and atmospheric moisture. It selectively allows beneficial moisture to activate the Lewis bases while blocking harmful moisture from reaching and degrading the perovskite crystal structure, thus protecting the high-Voc material from hygroscopic degradation.
3Reliability
If quaternary ammonium halides are used for passivation, then open-circuit-voltage deficit is reduced, but reproducibility of device performance becomes difficult to control
Solution Approach 1:
The invention changes the chemical state of the passivation layer from permanently active to conditionally active. By controlling the activation parameter (moisture exposure), the device performance becomes more predictable and reproducible, as the passivation effect is triggered in a controlled manner rather than being present from the start, which can cause variability.
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 use of HUBLA material enhances the power conversion efficiency of perovskite solar cells up to 22.3% and maintains more than 85% efficiency after 3500 hours of storage under ambient conditions, addressing the stability issues caused by environmental factors.
Implementation Method 1
The introduction of dynamic covalent bond gives the material the ability to absorb moisture
Implementation Method 2
The introduction of dynamic covalent bond gives the material the ability to absorb moisture and then releases Lewis bases to heal the defects
Data Source
AI summary
Disclosed is a passivated perovskite structure containing a perovskite layer; and a hindered urea bond-based Lewis acid-base containing layer adjacent the perovskite layer. Also disclosed are solar cells containing the passivated perovskite structure.