Low Bandgap Perovskite Composition for Solar Cells
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Solution Overview
Problem
Current perovskite solar cells (PSCs) face challenges due to their high bandgap, which limits efficiency and stability, particularly for single-junction and tandem devices, necessitating the development of lower bandgap perovskite compositions suitable for industrial-scale production.
Innovation Solution
A composition with stoichiometry A1-xFAxSn1-yBy(I1-zXz)3, where A and B are cations, X is a halide, and specific additives like SnCl2·xFACl are used to achieve a bandgap between 1.1 eV and 1.5 eV, improving grain size, residual stress, and dark carrier density, enhancing the structural and optoelectronic properties of perovskite films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional Pb-based halide perovskites with bandgaps between 1.5 eV and 1.7 eV are used, then the solar cells achieve reasonable stability, but the power conversion efficiency is limited due to the higher bandgap being substantially higher than the ideal 1.34 eV for single-junction solar cells
Solution Approach 1:
The patent applies parameter changes by modifying the bandgap of perovskite materials from the conventional 1.5-1.7 eV range down to 1.1-1.5 eV through compositional adjustments. Specifically, the invention uses a mixed cation approach with A1-xFAx (where FA is formamidinium and A is cesium or methylammonium) and mixed halide approach with (I1-zXz) (where X is bromide or chloride), thereby reducing the bandgap to better match the ideal 1.34 eV for single-junction solar cells, reducing energy loss while maintaining stability through optimized composition ratios
Solution Approach 2:
The patent employs composite materials by creating a multi-component perovskite system combining different cations (cesium, formamidinium, methylammonium), different B-site metals (lead, tin), and different halides (iodide, bromide, chloride). This composite approach allows tuning of both bandgap and stability properties, achieving the optimal balance between reduced energy loss and maintained reliability that cannot be achieved with single-component perovskites
2Productivity
If the bandgap is reduced to achieve higher efficiency, then the power conversion efficiency improves by approaching the Shockley-Queisser limit, but the stability and operational durability may deteriorate
Solution Approach 1:
The patent uses parameter changes to optimize the duration of action by carefully controlling the compositional parameters of the perovskite. The invention specifies precise ranges for cation ratios (0.5 ≤ x ≤ 0.9 for FA content), B-site metal ratios (0.5 ≤ y ≤ 0.9 for Sn content), and halide ratios (0 ≤ z ≤ 1 for bromide/chloride content), thereby achieving bandgaps of 1.1-1.5 eV that enable high productivity while maintaining operational stability through the balanced composition that prevents degradation
Solution Approach 2:
The patent applies composite materials to resolve the contradiction between efficiency and durability by creating a robust multi-element perovskite system. The mixed cation (A1-xFAx), mixed B-site (Sn1-yBy), and mixed halide (I1-zXz) composition provides both the reduced bandgap for high power conversion efficiency and the structural stability for long operational life, with each component contributing to either efficiency or stability properties
3Manufacturing precision
If additives like SnCl2·xFACl are used to improve grain size and reduce residual stress, then the structural properties and optoelectronic performance are enhanced, but the manufacturing process complexity increases
Solution Approach 1:
The patent uses intermediary substances (additives containing SnCl2·xFACl where 1.5 ≤ x ≤ 4.5) that mediate the formation process to achieve precise control over grain size (750-850 nm) and residual stress (0-40 MPa). These additives act as intermediaries that facilitate controlled crystallization and stress management during film formation, enabling high manufacturing precision while the specific concentration range (0.1-10 mol %) keeps the process complexity manageable
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 approach results in high power-conversion efficiency approaching 20% for MA-free Sn—Pb-based PSCs, with improved stability maintaining over 80% of initial efficiency after 750 hours under continuous operation, and reduced residual stress, leading to enhanced operational stability and efficiency.
Implementation Method 1
Perovskite solar cells (PSCs) have emerged as a next generation photovoltaic (PV) technology
Implementation Method 2
adding an additive to the mixture, and treating the mixture. Further, the treating results in the forming of the perovskite having a stoichiometry comprising A1-xFAxSn1-yBy(I1-zXz)3
Data Source
AI summary
The present disclosure relates to a composition that includes a perovskite having a stoichiometry comprising A1-xFAxSn1-yBy(I1-zXz)3, where A is a first cation, B is a second cation, X is a halide, and 0.5≤x≤0.9, 0.5≤y≤0.9, and 0≤z≤1. In some embodiments of the present disclosure, A may include at least one of cesium, guanidinium, and/or methylammonium. In some embodiments of the present disclosure, X may include at least one of bromide and/or chloride. In some embodiments of the present disclosure, z may be equal to zero.