Biocompatible and flexible peptide assemblies have emerged as a promising class of piezoelectric materials for biomechanical energy harvesting, offering a viable pathway toward the self-powered operation of wearable and implantable electronic devices. However, despite substantial progress primarily driven by extensive investigations of homochiral L-diphenylalanine and its derivatives, the vast structural diversity of short peptides, particularly that arising from heterochiral sequences, remains largely unexplored. Herein, we successfully synthesized a series of L/D-containing dipeptides Boc-L-Ile-D-Phe-OMe (2) and Boc-L-Ile-D-Phg-OMe (4), along with their all-L counterparts Boc-L-Ile-L-Phe-OMe (1) and Boc-L-Ile-L-Phg-OMe (3), in which Phg is a close analogue of Phe with a side chain shortened by one methylene unit. These peptides were assembled into continuous, unidirectional and densely packed supramolecular architectures through a dip-coating technique. Piezoresponse force microscopy (PFM) results revealed effective d33 coefficients of 2.15, 3.26, 4.63, and 6.31 pm V-1 for peptides 1, 2, 3, and 4 respectively, exhibiting a clear ascending trend (1 < 2 < 3 < 4) that is further confirmed by density functional theory (DFT) calculations. Correspondingly, piezoelectric generators fabricated from the L/D-containing peptide 4 exhibited the highest open-circuit voltage of 3.30 V under an applied force of 35 N, while devices based on peptide 3 generated a short-circuit current of 80 nA under 43 N. Notably, these values outperform previously reported peptide-based piezoelectric generators, underscoring the considerable potential of these materials for efficient biomechanical energy conversion. These findings establish a clear relationship between piezoelectric responses and molecular features, particularly side-chain configuration and residue chirality, thereby expanding the design space of peptide-based piezoelectric materials and enabling performance optimization beyond conventional homochiral systems.