Ionic Accumulation as a Diagnostic Tool in Perovskite Solar Cells: Characterizing Band Alignment with Rapid Voltage Pulses.
Ionic Accumulation as a Diagnostic Tool in Perovskite Solar Cells: Characterizing Band Alignment with Rapid Voltage Pulses.
复制标题
离子积累作为钙钛矿太阳能电池的诊断工具：用快速电压脉冲表征能带对准。
DOI：
10.1002/adma.202302146
复制
发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Hill NS
中科院分区：
文献类型：
--
作者：
Hill NS
尽管有创纪录的设备，但钙钛矿太阳能电池中的界面仍然知之甚少，阻碍了进一步的进展。它们的混合离子-电子性质导致界面处的成分变化，这取决于外部施加偏压的历史。这使得难以精确地测量电荷提取层的能带能量对准。因此，该领域经常采用试错过程来优化这些接口。目前的方法通常是在真空中和不完整的细胞上进行，因此值可能无法反映在工作设备中发现的值。为了解决这个问题，开发了一种脉冲测量技术，其特征在于功能器件中钙钛矿层上的静电势能降。该方法针对一系列稳定化偏压重建电流-电压（JV）曲线，在随后的快速电压脉冲期间保持离子分布“静态”。观察到两种不同的状态：在低偏置下，重建的JV曲线是“s形”，而在高偏置下，返回典型的二极管形曲线。使用漂移扩散模拟，证明了两种机制的交叉点反映了界面处的带偏移。这种方法有效地允许在照明下测量完整器件中的界面能级对准，而不需要昂贵的真空设备。
Despite record‐breaking devices, interfaces in perovskite solar cells are still poorly understood, inhibiting further progress. Their mixed ionic‐electronic nature results in compositional variations at the interfaces, depending on the history of externally applied biases. This makes it difficult to measure the band energy alignment of charge extraction layers accurately. As a result, the field often resorts to a trial‐and‐error process to optimize these interfaces. Current approaches are typically carried out in a vacuum and on incomplete cells, hence values may not reflect those found in working devices. To address this, a pulsed measurement technique characterizing the electrostatic potential energy drop across the perovskite layer in a functioning device is developed. This method reconstructs the current‐voltage (JV) curve for a range of stabilization biases, holding the ion distribution “static” during subsequent rapid voltage pulses. Two different regimes are observed: at low biases, the reconstructed JV curve is “s‐shaped”, whereas, at high biases, typical diode‐shaped curves are returned. Using drift‐diffusion simulations, it is demonstrated that the intersection of the two regimes reflects the band offsets at the interfaces. This approach effectively allows measurements of interfacial energy level alignment in a complete device under illumination and without the need for expensive vacuum equipment.