Carrier‐Transport Mechanism in Organic Antiambipolar Transistors Unveiled by Operando Photoemission Electron Microscopy

Abstract

Figure 5. a-c) Illustrations and the energy-level alignments of AAT in the following

Output and Negative‐Region Characteristics in Organic Anti‐Ambipolar Transistors

“…This indicates that electrons and holes recombine near the lateral interfaces of AATs. [ 32 ] Otherwise, the observed current should be larger than the calculated ones since no carrier transport from n–type to p–type, or p–type to n–type is considered in our calculations.…”

Antiambipolar, ambipolar, and unipolar charge transport in organic transistors based on a single vertical P–N heterointerface

“…However, most studies have shown that the lateral heterointerface plays a determined role in OHJT. 39,40 Here, our results indicate that it may be achieved from devices with a single vertical organic heterointerface. In previous reports, ambipolar and depleted unipolar charge properties are ordinary from OHJT devices.…”

Surface Potential Visualization in Organic Antiambipolar Transistors Using Operando Kelvin Probe Force Microscopy for Understanding the Comprehensive Carrier Transport Mechanism

“…In our previous study, we revealed that the Λ‐shaped transfer curve of the AAT can be analyzed as the overlapped drain current in the saturation regions of the constituent transistors in the same analogy as that of the shoot‐through current (STC) in complementary metal–oxide semiconductor (CMOS) inverters. [ 28–30,41 ] The I D – V G curve of the AAT is generally given by the following equations: [ 38–40,43 ] $$\[ \begin{array}{*{20}{c}}{{I_{D,n}} = \frac{W}{{2{L_n}}}{\mu _n}{C_i}{{({V_G} - {V_{th,n}})}^2}}\end{array} \]$$ $$\[ \begin{array}{*{20}{c}}{{I_{D,p}} = \frac{W}{{2{L_p}}}{\mu _p}{C_i}{{({V_D} - {V_G} + {V_{th,p}})}^2}}\end{array} \]$$where L n and L p are the effective channel lengths of the PTCDI‐C8 and α‐6T channels, respectively (here, 20 and 30 µm for the PTCDI‐C8 and α‐6T channels, respectively, given the p–n‐stacked layers with 35 µm width), W is the common channel width (400 µm), and C i is the capacitance of the insulator per unit area (73.5 nF cm −1 ). Moreover, I D,n , µ n , and V th,n are the PTCDI‐C8 transistor's I D in the saturation region, electron carrier mobility, and threshold voltage, respectively.…”

“…The carrier transport mechanisms are basically the same as those proposed by PEEM measurements in our previous work. [ 43 ] The HOMO and LUMO energy levels of the PTCDI‐C8 and α‐6T layers and the Fermi level of Au electrodes were evaluated in that work. When V G is < V on , holes are accumulated in the α‐6T channel due to the effective gate voltage ( V D − V G ) (Figure 5a).…”