Capillary-Bridge Controlled Patterning of Stable Double-Perovskite Microwire Arrays for Non-toxic Photodetectors.

Yueyang Pi,Jiangang Feng,Chi Zhang,Jinjin Zhao,Hanfei Gao,Lei Jiang,Yingjie Zhao,Yuchen Wu

doi:10.3389/fchem.2020.00632

Abstract

Single-crystalline lead halide perovskites with remarkable physical properties offer great potential in integrated optoelectronic applications but are restricted by their instability and toxicity. To address these problems, various strategies including lead-free halide double perovskites with high stabilities of heat, light, and moisture have been developed. However, it still requires an efficient method to pattern single-crystalline, double-perovskite micro-/nanostructures with strict alignment and ordered orientation for the integration of optoelectronic devices. Here, our solution-processing approach employs capillary bridges to control the dewetting dynamics and confine the crystallization in the assembly of non-toxic Cs2AgBiBr6 microwire arrays. We demonstrate the strict alignment, high crystallinity, eliminated grain boundary, and ordered orientation of these as-prepared single-crystalline, double-perovskite microwire arrays. Based on these high-quality microwire arrays, we fabricate high-performance photodetectors with a responsivity of 1,625 A W−1, on/off ratio of 104, and fast response speed of τdecay = 0.04 ms and τrise = 0.28 ms. The long-term crystallographic and spectroscopic stability of Cs2AgBiBr6 microwire arrays has also been demonstrated through the 1 month exposure to air conditioning. Our strategy provides a new perception to fabricate stable perovskite microarrays for the integration of non-toxic optoelectronic devices.

Highlights

A droplet of double-perovskite precursor was injected onto the asymmetric wettability template and covered with a flat substrate to fabricate the Cs2AgBiBr6 microwire arrays
With the evaporation of the solvent, the continuous liquid film was separated into discrete line-shape capillary bridges pinned between superhydrophilic tops of the template and the substrate
Once the solution saturated in capillary bridges, Cs2AgBiBr6 crystals would nucleate and constantly grow at the site pinned between micropillar tops and the target substrate

Summary

INTRODUCTION

A micropillar-structured template with asymmetric wettability of superhydrophilic tops and hydrophobic sidewalls is introduced to guide the formation of capillary bridges and direct dewetting process These capillary bridges guarantee the controllable crystallization of Cs2AgBiBr6 microwires with regular positioning and strict spatial confinement, yielding perovskite microwire arrays with precise alignment, ordered orientation, and high crystallinity. Compared to the polycrystalline film, Cs2AgBiBr6 microwire arrays with high crystalline quality exhibit higher optoelectronic responsiveness because of their low defect density and suppressed grain boundary Based on these single-crystalline, double-perovskite microwires, highperforming photodetectors were demonstrated with a high responsivity of 1,625 A W−1, a high light on/off ratio of 104, a short decay time of 0.04 ms, and the rise time of 0.28 ms. The pure-phase Cs2AgBiBr6 double-perovskite microwire arrays with high crystallinity, long-term stability, and suppressed grain boundary were prepared by a capillary-bridge-mediated assembly method which refers to a dewetting process guided by the micropillar-structured template with asymmetric wettability. The light irradiance of a lightemitting diode (LED, 455 nm) was tuned and mediated by a LED controller (Thorlabs DC2200) and silicon photodiode (Thorlabs, S130C), respectively

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT