Two novel fluorenyl-porphyrins 2Flu-TPP and 4Flu-TPP serving as charge trapping elements are designed and synthesized through BF ₃.Et ₂O catalyzed Friedel-Crafts reaction. With steric hindrance building blocks of fluorene units, 2Flu-TPP and 4Flu-TPP present highly nonplanar 3-dimensional structure, which could effectively inhibit molecular packing and intermolecular arrangement of porphyrins. As charge trapping elements, porphyrin groups provide the hole trapping sites, while fluorene units act as a hole blocking group to reduce the formation of leakage current paths. The pentacene-based organic field effect transistor memory devices based on 2Flu-TPP and 4Flu-TPP show memory windows of 48.93 and 49.20 V, respectively. The 2Flu-TPP device shows reliable endurance property with a large ON/OFF current ratio (1.1×10 ⁷) and good charge retention time (2.41×10 ⁵ after 2×10 ³ s). This study suggests that porphyrin based steric hindrance small molecular elements have great promise for high-performance organic field effect transistor memory.