Ultrathin, solution-processed emerging solar cells with high power-per-weight (PPW) outputs demonstrate unique potential for applications where low weight, high power output, and flexibility are indispensable. The following perspective explores the literature of emerging PVs and highlights the maximum reported PPW values of perovskite solar cells (PSCs) 29.4 W/g, organic solar cells (OSCs) 32.07 W/g, and quantum dot solar cells 15.02 W/g, respectively. The record PPW values of OSCs and PSCs are approximately one order of magnitude higher compared to their inorganic ultrathin solar cells counterparts (approximately 3.2 W/g for CIGS and a-Si). This consists emerging PVs, very attractive for a variety of applications where the PPW is the key parameter. In particular, both OSCs and PSCs can be implemented in different scenarios of applications (indoor and biocompatible applications for OSCs and outdoor and high-energy radiation conversion conditions for the PSCs) due to their unique optoelectronic and physiochemical properties. Finally, our theoretical optical and electrical simulation and optimization study for the most promising and well-suited PV technologies showed an impressive maximum realistic theoretical PPW limit of 74.3 and 93.7 W/g for PSCs and OSCs, respectively. Our finding in the theoretical section shows that the experimental results achieved in the literature of PSCs and OSCs toward high PPW outputs is not quite close to the theoretical maximum (35% and 40% of the theoretical maximum for OSCs and PSCs, respectively), and thus, more work needs to be done to further increase the experimental PPWoutput of these promising PV technologies.