Thiophene-Functionalized Hybrid Perovskite Microrods and their Application in Photodetector Devices for Investigating Charge Transport Through Interfaces in Particle-Based Materials

Tom Kollek; Daniel Wurmbrand; Susanne T Birkhold; Eugen Zimmermann; Julian Kalb; Lukas Schmidt-Mende; Sebastian Polarz

doi:10.1021/acsami.6b12466

Thiophene-Functionalized Hybrid Perovskite Microrods and their Application in Photodetector Devices for Investigating Charge Transport Through Interfaces in Particle-Based Materials

ACS Appl Mater Interfaces. 2017 Jan 11;9(1):1077-1085. doi: 10.1021/acsami.6b12466. Epub 2016 Dec 20.

Authors

Tom Kollek¹, Daniel Wurmbrand¹, Susanne T Birkhold¹, Eugen Zimmermann¹, Julian Kalb¹, Lukas Schmidt-Mende¹, Sebastian Polarz¹

Affiliation

¹ University of Konstanz , Universitaetsstrasse 10, 78457 Konstanz, Germany.

PMID: 27935284
DOI: 10.1021/acsami.6b12466

Abstract

Particle-based semiconductor materials are promising constituents of future technologies. They are described by unique features resulting from the combination of discrete nanoparticle characteristics and the emergence of cooperative phenomena based on long-range interaction within their superstructure. (Nano)particles of outstanding quality with regards to size and shape can be prepared via colloidal synthesis using appropriate capping agents. The classical capping agents are electrically insulating, which impedes particle-particle electronic communication. Consequently, there exists a high demand for realizing charge transport through interfaces especially for semiconductors of relevance like hybrid perovskites (HYPEs), for example, CH₃NH₃PbI₃ (MAPI) as one of the most prominent representatives. Of particular interest are crystals in the micrometer range, as they possess synergistic advantages of single crystalline bulk properties, shape control as well as the possibility of being functionalized. Here we provide a synthetic strategy toward thiophene-functionalized single crystalline MAPI microrods originating from the single source precursor CH₃NH₃PbI₃TEG₂ (TEG = triethylene glycol). In the dark, the microrods show enhanced charge transport characteristics of holes over 2 orders of magnitude compared to microscale cuboids with insulating alkyl surface modifiers and nonfunctionalized random sized particles. In large-area prototype photodetector devices (2.21 cm²), the thiophene functionalization improves the response times because of the interparticle charge transport (t_ON = 190 ms, t_OFF = 430 ms) compared to alkyl-functionalized particles (t_ON = 1055 ms, t_OFF = 60 ms), at similar responsivities of 0.65 and 0.71 mA W^-1, respectively. Further, the surface functionalization and crystal grains on the micrometer scale improve the device stability. Therefore, this study provides clear evidence for the interplay and importance of crystal size, shape and surface modification of MAPI crystals, which is of major importance in every optoelectronic device.

Keywords: electronic transport; hybrid perovskites; particle shape; semiconductor nanostructures; surface functionalization.