This study presents a highly stretchable, transparent, and conductive polymer, PEDOT/STEC, developed for flexible electronics. The polymer is composed of poly(3,4-ethylenedioxythiophene) (PEDOT) and a small molecule ionic additive (STEC), which enhances both stretchability and conductivity. The STEC additives, such as STEC1, 2, and 3, are effective plasticizers that improve the mechanical properties of PEDOT:PSS films while maintaining high electrical conductivity. The films exhibit a maximum tensile strain of over 100% and a conductivity exceeding 100 S/cm, making them suitable for use as electrodes or interconnects in stretchable devices. The mechanical properties of the PEDOT/STEC films were characterized using techniques such as stress/strain analysis, strain cycling, and frequency sweep experiments. The films demonstrated a relaxation time of approximately 72 seconds and a high storage modulus, indicating their solid-like behavior despite the high concentration of STEC. Scanning electron microscopy (SEM) revealed a densely packed, solid interior, confirming the effective dispersion of STEC within the polymer matrix. The electrical properties of the PEDOT/STEC films were evaluated, showing a significant increase in conductivity compared to pure PEDOT:PSS. The addition of STEC enhances the crystallinity of the PEDOT-rich domains, which contributes to improved conductivity. The films also exhibit a mixed ion-electron conductivity, with both electronic and ionic contributions to the overall conductivity. The study also investigated the effect of tensile strain on the PEDOT/STEC films, revealing that the films maintain their conductivity even under high strain. The films showed a significant increase in conductivity from 0% to 100% strain along the stretching direction, likely due to the alignment of PEDOT chains. The films also demonstrated good cycling stability, with minimal degradation after 1000 stretching cycles. The PEDOT/STEC films were tested as interconnects for flexible field-effect transistor (FET) arrays, showing excellent performance under various stretching conditions. The films were used in both one-dimensional and two-dimensional arrays, demonstrating their versatility in flexible electronics applications. The study highlights the potential of PEDOT/STEC as a promising material for stretchable, transparent, and conductive devices in flexible electronics.This study presents a highly stretchable, transparent, and conductive polymer, PEDOT/STEC, developed for flexible electronics. The polymer is composed of poly(3,4-ethylenedioxythiophene) (PEDOT) and a small molecule ionic additive (STEC), which enhances both stretchability and conductivity. The STEC additives, such as STEC1, 2, and 3, are effective plasticizers that improve the mechanical properties of PEDOT:PSS films while maintaining high electrical conductivity. The films exhibit a maximum tensile strain of over 100% and a conductivity exceeding 100 S/cm, making them suitable for use as electrodes or interconnects in stretchable devices. The mechanical properties of the PEDOT/STEC films were characterized using techniques such as stress/strain analysis, strain cycling, and frequency sweep experiments. The films demonstrated a relaxation time of approximately 72 seconds and a high storage modulus, indicating their solid-like behavior despite the high concentration of STEC. Scanning electron microscopy (SEM) revealed a densely packed, solid interior, confirming the effective dispersion of STEC within the polymer matrix. The electrical properties of the PEDOT/STEC films were evaluated, showing a significant increase in conductivity compared to pure PEDOT:PSS. The addition of STEC enhances the crystallinity of the PEDOT-rich domains, which contributes to improved conductivity. The films also exhibit a mixed ion-electron conductivity, with both electronic and ionic contributions to the overall conductivity. The study also investigated the effect of tensile strain on the PEDOT/STEC films, revealing that the films maintain their conductivity even under high strain. The films showed a significant increase in conductivity from 0% to 100% strain along the stretching direction, likely due to the alignment of PEDOT chains. The films also demonstrated good cycling stability, with minimal degradation after 1000 stretching cycles. The PEDOT/STEC films were tested as interconnects for flexible field-effect transistor (FET) arrays, showing excellent performance under various stretching conditions. The films were used in both one-dimensional and two-dimensional arrays, demonstrating their versatility in flexible electronics applications. The study highlights the potential of PEDOT/STEC as a promising material for stretchable, transparent, and conductive devices in flexible electronics.