Assessment of the Factors Influencing Charge‐Carrier Mobility Measurements in Organic Field‐Effect Transistors

Abstract

Evaluation of the charge mobilities is a critical link in the development of organic semiconductors and the associated devices. One of the most widely used measurements relies on an organic field-effect transistor (OFET) configuration. It is based on a relationship between charge-carrier mobility and current-voltage curves, which happens to often exclude factors that are extrinsic to the organic semiconductor but can in fact significantly affect the measured current. The consequence is that the actual meaning of the mobilities evaluated in this way remains ambiguous. As such, it is unclear how well OFET data represent the actual charge-transport properties of the organic semiconductors. Here, by employing a molecular-scale OFET device model that directly connects microscopic charge transfer to macroscopic current characteristics, the mobilities in an OFET configuration and their relationships to the bulk mobilities are investigated. Specifically, the role of disorder, nature of the semiconductor-dielectric interface, and presence of non-Ohmic contacts are addressed. By explicitly including these factors that are frequently impeding a clear evaluation of the experimental data, the study represents a major step into a robust molecular-scale description of OFET operation.

Precise Extraction of Charge Carrier Mobility for Organic Transistors

“…Recently, several papers have been published on mobility extraction, the roots of the misconceptions about mobility and the relevant extraction methods; however, a systematic illustration of the problem is still lacking. Additionally, determination of ways to avoid errors in mobility evaluation, including device fabrication aspects, the measurement setup configuration, and the bias and temperature dependences, remains an urgent problem.…”

Addition of the Lewis Acid Zn(C6F5)2 Enables Organic Transistors with a Maximum Hole Mobility in Excess of 20 cm2 V−1 s−1

“…Furthermore, solution‐processed mobilities approaching single‐crystal‐like values have been achieved in small‐molecule:polymer blend OTFTs doped with B(C 6 F 5 ) 3 . Furthermore, the effects of B(C 6 F 5 ) 3 on µ are more important now than ever, considering the recent spate of overestimated µ values that have contaminated the literature . Given the broad applicability of B(C 6 F 5 ) 3 , we wondered whether other molecular Lewis acids with similar multifunctional properties, and influences on µ , exist.…”

Vertical Organic Field‐Effect Transistors

“…1) The performances of currently reported VOFETs and their functional devices are still relatively low, which are needed further improvements from aspects of developing high performance organic semiconductors, the further optimization of device structures and device fabrication techniques. Although great progress regarding simulation techniques recently has been achieved for traditional OFETs, [142,143] comparable work is less developed for VOFETs, which is also needed to be strengthened in future. [33,36] 2) OSSCs are one of the best candidates for high performance organic electronic and optoelectronic devices and circuits.…”

“…5) In addition, development of device models and device simulation techniques is also very crucial to both fundamental studies and practical applications of VOFETs. Although great progress regarding simulation techniques recently has been achieved for traditional OFETs, [142,143] comparable work is less developed for VOFETs, which is also needed to be strengthened in future. Anyway, with the solution of these above mentioned challenges and under the joint effect of scientists from various fields, it is believed that these will contribute the next step rapid development for VOFETs and their related fields in organic electronics and optoelectronics.…”