Visualizing carrier transport in hybrid-perovskite based lateral metal-semiconductor-metal structures
N. Ganesh a, A.Z. Ashar a, Sumukh Purohit a, K.L. Narasimhan b, K.S. Narayan a
a Chemistry and Physics of Materials Unit (CPMU), Jawaharlal Nehru Center for Advanced Scientific Research, Jakkuru, Bengaluru, Karnataka 560064, India, Bengaluru, India
b Center for Nano Science and Engineering (CENSE), Indian Institute of Science, Bengaluru, India
Proceedings of SUNRISE September Symposium 2021 ‘Powering Green Recovery’ (SUNRISEIII)
Online, Spain, 2021 September 20th - 22nd
Organizers: Hari Upadhyaya, Adrian Walters, James Durrant, Sara Walters and Georgia Bevan
Invited Speaker, N. Ganesh, presentation 043
Publication date: 14th September 2021

The high performance of hybrid perovskite-based devices is attributed to its excellent bulk-transport properties. However, carrier dynamics at the metal-perovskite interface and its influence on device operation are not widely understood. Here we explore the microscopic origins of the dominant transport mechanisms in methylammonium lead iodide (MAPbI3) perovskite-based asymmetric metal-electrode lateral devices, with inter-electrode length varying from 4 μm to 120 μm. The device operation characteristics exhibit a cross-over of the transport regimes, from the ohmic to the space-charge limited current (SCLC) characteristic as a function of the inter-electrode length and the applied bias. The potential landscape imaged using spatially resolved Kelvin-probe measurements indicates the presence of a transport barrier at the metal-MAPbI3 interface. Additional observation of a finite electric field across the bulk confirms minimal ion-screening effects on the observed transport characteristics. Further, we study the influence of local photo-excitation using near-field scanning photocurrent microscopy. Photocurrent profiles across the device exhibit dominant recombination and charge-separation zones. In the presence of an external bias, the asymmetric photocurrent profile points to the unbalanced nature of carrier transport. These lateral devices exhibit photodetector characteristics with a responsivity of ≈ 54 mA/W in self-powered mode, and ≈ 6.2 A/W at 5 V bias, in short-channel devices (4 μm). Moreover, the low device capacitance enables light-switching transient response of ~12 ns, suitable for high-speed operational applications.
 

We acknowledge the Department of Science and Technology, Government of India, and EPSRC-UKRI Global Challenge Research Fund project, SUNRISE (EP/P032591/1), for the financial assistance. SP acknowledges DST-INSPIRE for the fellowship.

© FUNDACIO DE LA COMUNITAT VALENCIANA SCITO
We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info