A new strategy via double C–H activation cyclization has been developed for the versatile synthesis of IDBT derivatives with quite different photoelectric properties. Single-crystal field-effect transistors based on IDBT-l-TIPSA delivered high and balanced charge carrier mobilities of up to 0.64 cm² V⁻¹ s⁻¹ for holes and 0.34 cm² V⁻¹ s⁻¹ for electrons under ambient conditions.