Ultrasensitive 1D field-effect phototransistor: CH$_3$NH$_3$PbI$_3$ nanowire sensitized individual carbon nanotube

TL;DR

This paper reports a highly sensitive field-effect phototransistor using a carbon nanotube sensitized by CH$_3$NH$_3$PbI$_3$ nanowires, achieving unprecedented responsivity and revealing complex charge transfer phenomena.

Contribution

It introduces a novel CNT-based phototransistor with record responsivity and provides detailed insights into charge transfer and photo-doping mechanisms at the interface.

Findings

Record light responsivity of 7.7x10^5 A/W at low light levels.

Negative photocurrent and device insulating behavior at high illumination.

Evidence of photo-doping at the CNT-perovskite interface.

Abstract

Field-effect phototransistors were fabricated based on individual carbon nanotubes (CNTs) sensitized by CH$_3$NH$_3$PbI$_3$ nanowires (MAPbI$_3$NW). These devices represent light responsivities of R=7.7x10$^5$ A/W at low-lighting conditions in the nWmm$^{-2}$ range, unprecedented among CNT-based photo detectors. At high incident power (~1 mWmm$^{-2}$), light soaking results in a negative photocurrent, the device turns insulating. We interpret the phenomenon as a result of efficient electron-hole separation and charge transfer of holes from the perovskite to the carbon nanotube, which improves conductance by increasing the number of carriers, but leaves electrons behind. At high illumination intensity the random electrostatic potential of these quench the mobility in the nanotube. The single CNT device geometry allows the local study of the MAPbI$_3$NW/CNT interface for metallic and semiconducting CNTs separately. Infrared and Raman spectroscopy studies of CNT-CH$_3$NH$_3$PbI$_3$ composites revealed that photo-doping takes place at the interface.