Photoelectrochromic devices (PECDs) function as self-powered smart windows by dynamically modulating optical transmittance and minimizing heat gain, thereby lowering energy load for heating, ventilating, and air conditioning (HVAC) systems. Simultaneously, the integrated photovoltaic (PV) component enables solar energy harvesting, making PECDs particularly attractive in building-integrated photovoltaics (BIPVs). Thus, PECDs offer a promising and feasible approach for decreasing HVAC energy loads by adapting sunlight entering the building with controlling visual comfort and generating energy as well. In the talk, we will first present the principal working mechanism and performance factors of PECDs. We then follow with a classification and discussion of different PECD architectures. Particularly, we classify them into six categories: (i) separated, (ii) patterned, (iii) combined, (iv) partly covered, (v) hybrid, and (vi) other emerging PECDs with presenting recent progress for each category. Finally, we address existing challenges with perspectives toward multifunctional PECDs capable of smart energy-efficient windows and sustainable BIPVs.