Dinaphtho[2,3-b:2 & PRIME;,3 & PRIME;-f]thieno[3,2-b]thiophene photoresistor: Generation of photocarriers and charge trapping

Author(s)

Fernandes, Jose Diego ; Vieira, Douglas Henrique ; Klem, Maykel dos Santos ; Alves, Neri

• Document type: Journal article
• Source: MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING; v. 165, p. 10-pg., 2023-06-06.

Abstract

Thin films of organic semiconductors have been used as active layer in several electronic devices. The molecular organization of the active layer can be a critical parameter to optimize the performance of these devices. In this work, a thin film photoresistor of Dinaphtho[2,3-b:2 & PRIME;,3 & PRIME;-f]thieno[3,2-b]thiophene (DNTT) was fabricated using physical vapor deposition (PVD) technique with the most appropriate molecular organization to obtain better performance. The DNTT photoresistor current exhibited a significant increase under ultraviolet (UV) light (& lambda; = 390 nm, Pd = 1.73 W/m2), achieving an IUV/IDark ratio of 1 x 105 at V =-1.5 V. The photoresistor DNTT achieved good values for the most important photodetector's figures of merit (FOMs), such as responsivity of 722.3 mA/W, detectivity of 1.0 x 1013 Jones and external quantum efficiency of 23000%. The measurements of real (Z & PRIME;) and imaginary (Z & DPRIME;) impedance in the dark indicated that the electrical relaxation process is slow and of the Debye type. Nyquist plots revealed the appearance of negative capacitance (NC) at low frequencies when the photoresistor is under illumination, indicating that the photogenerated carriers can be trapped. The alternating current (AC) conductivity (& sigma;AC) measurements under lighting suggest that charge transfer occurs by hopping and those charge carriers can tunnel through the space charge region (SCR) with built-in potential generated by charges trapped. Therefore, the results showed that although the DNTT photoresistor has a good photocon-ductive response, its performance can be improved by reducing of traps. (AU)

• FAPESP's process: 20/12060-1 - EGOFETs and Schottky diode: influence of the supramolecular arrangement on electrical properties
• Grantee: José Diego Fernandes Dias
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 13/14262-7 - Nanostructured films from biologically-relevant materials
• Grantee: Osvaldo Novais de Oliveira Junior
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 20/12282-4 - Development of vertical electrolyte-gated field effect transistors for UV photodetectors
• Grantee: Douglas Henrique Vieira
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 18/02604-4 - Study of printed supercapacitors integrating electrolyte-gated transistors
• Grantee: Maykel dos Santos Klem
• Support Opportunities: Scholarships in Brazil - Doctorate