Crystalline, electrically conductive molecules that transport charge carriers efficiently are candidates for next-generation printable optoelectronic devices. Here, we have designed a series of D-pi-D porphyrin molecular systems as either a free-base or with coordinated metals (Cu and Zn) via high yield, low-temperature synthetic procedures. The D-pi-D porphyrin molecular systems (coded as HPPHT, CPPHT and ZPPHT) were comprehensively investigated employing electrical and electrochemical methods, optical absorption spectroscopy, XRD, and XPS to identify their energy levels, optical, electrical and structural properties. The studies revealed that the D-pi-D porphyrin molecular systems were crystalline, with desirable energy levels and superior electrical properties compared to the benchmark Spiro-OMeTAD under similar conditions. Among these molecular systems, CPPHT exhibited an activation energy of 0.13 eV and a higher charge carrier density (N-d similar to 4.84 x 10(13) cm(-3)), when compared to the HPPHT (4.20 x 10(11) cm(-3), 0.13 eV) and ZPPHT (1.92 x 10(12) cm(-3), 0.17 eV) systems. These molecular systems were introduced as hole transport materials into pre-made perovskite solar cells (without a HTM) by a simple infiltration process via the front contact layer. Among the three systems studied, CPPHT solar cells showed the highest photo-current density (Jsc) of 20.44 mA.cm(-2) and power conversion efficiency (PCE) of 11.76% when compared with the H/ZPPHT devices under AM 1.5G (100 mW.cm(-2)) illumination; signifying lower recombination at the interface of the CPPHT/perovskite (MAPbI(3)). Incorporation of Li-TFSI/t-BP additives on the device surface improved the HTM-MAPbI(3) interface, and increased the Jsc to 21.35 mA.cm(-2) with a PCE of 12.88% for CPPHT devices. These D-pi-D porphyrin molecular systems under ambient conditions demonstrated excellent short-term and operational stability in the presence of moisture. The modified device architecture opens up a novel configuration for designing high-performance optoelectronic devices.