[论文解读] From Dye Sensitized to Perovskite Solar Cells, The Missing Link

So‐Min Yoo, Seog Joon Yoon+4 more|arXiv (Cornell University)|May 28, 2019

Perovskite Materials and Applications参考文献 1被引用 38

一句话总结

本论文通过控制前驱体浓度将染料敏化太阳能电池的阻抗模式与钙钛矿太阳能电池联系起来，并提供一个等效电路模型以用传输和复合过程来解释 PSC 的阻抗。

ABSTRACT

Fundamental working mechanisms of perovskite solar cells remain an elusive topic of research. Impedance Spectroscopy (IS) application to perovskite-based devices generates uncommon features and misleading outputs, mainly due to the lack of a stablished model for the interpretation of the results. In this work we control the perovskite precursor concentration to fabricate a series of perovskite-based solar cells with different amounts of perovskite absorber. Low concentration devices present the well-known dye sensitized solar cell (DSSCs) impedance pattern. As the amount of perovskite is increased, the characteristic impedance spectra of thin-film perovskite solar cells (PSCs) arises. This transition is characterized by a change in the working principles, determined by an evolution of the dominant capacitance: from the intermediate frequency chemical capacitance of TiO2 in devices with isolated perovskite domains, to a large low-frequency capacitance signal which divides the spectra in two sections, yet with no direct influence in final device performance. This study allows to link experimentally, in terms of impedance behavior, PSCs with the rest of solar cell devices via DSSCs. We observe that it is not possible to assign a single physical origin to the different resistances determined in the impedance spectra except for the series resistance. In contrast, resistive element present contributions from different physical processes, observing a transport-recombination coupling. Based on this analysis we provide an equivalent circuit model to evaluate the impedance pattern of PSCs in terms of the processes directly affecting the final performance (i.e. considering transport-related and recombination-related losses), a crucial tool for further development of perovskite photovoltaics.

研究动机与目标

• 通过阻抗谱（IS）研究钙钛矿太阳能电池的基本工作机制。
• 探究改变钙钛矿前驱体浓度如何改变器件阻抗模式。
• 开发一个将阻抗特征映射到影响 PSC 性能的传输和复合过程的等效电路模型。

提出的方法

• 通过控制前驱体浓度制备一系列含钙钛矿吸收层量不同的钙钛矿太阳能电池。
• 测量器件的阻抗光谱，以观察从 DSSC 式模式过渡到 PSC 模式。
• 分析主导电容如何从 TiO2 化学电容演变为在增加钙钛矿含量时出现的大型低频电容。
• 提出一个将传输相关损耗与复合相关损耗在阻抗响应中分离的等效电路模型。

实验结果

研究问题

• RQ1 钙钛矿前驱体浓度如何影响太阳能电池的阻抗光谱？
• RQ2 PSC 阻抗是否可以用一个统一模型在 DSSC 式与 PSC 两个区间下进行解释？
• RQ3 除串联电阻外，PSC 阻抗光谱中的电阻元件的物理起源是什么？
• RQ4 传输和复合过程如何在阻抗测量中体现并与最终器件性能相关？

主要发现

• 低钙钛矿含量器件显示 DSSC 式阻抗模式。
• 增加钙钛矿含量使光谱转变为具有较大低频电容的典型 PSC 模式。
• 主导电容从与 TiO2 相关的化学电容演变为一个巨大的低频信号，该信号将光谱分成两部分，但并不直接决定最终性能。
• 阻性元件不能仅指向单一物理起源，除了串联电阻之外；它们反映了传输和复合共同贡献。
• 提供了一个等效电路模型，用于从传输相关和复合相关损失的角度评估阻抗。