ORCID Profile
0000-0001-5902-4187
Current Organisation
RWTH Aachen
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Publisher: Wiley
Date: 13-08-2021
Abstract: Solution‐processed halide perovskites have emerged as excellent optoelectronic materials for applications in photovoltaic solar cells and light‐emitting diodes. However, the presence of mobile ions in the material hinders the development of perovskite field‐effect transistors (FETs) due to screening of the gate potential in the nearby perovskite channel, and the resulting impediment to achieving gate modulation of an electronic current at room temperature. Here, room‐temperature operation is demonstrated in cesium lead tribromide (CsPbBr 3 ) perovskite‐based FETs using an auxiliary ferroelectric gate of poly(vinylidenefluoride‐ co ‐trifluoroethylene) [P(VDF‐TrFE)], to electrostatically fixate the mobile ions. The large interfacial polarization of the ferroelectric gate attracts the mobile ions away from the main nonferroelectric gate interface, thereby enabling modulation of the electronic current through the channel by the main gate. This strategy allows for realization of the p‐type CsPbBr 3 channel and revealing the thermally activated nature of the hole charge transport. The proposed strategy is generic and can be applied for regulating ions in a variety of ionic–electronic mixed semiconductors.
Publisher: American Chemical Society (ACS)
Date: 25-05-2021
Publisher: Wiley
Date: 29-06-2023
Abstract: 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.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Matthew Wolf.