Infrared Photovoltaic–Battery Hybrid Systems Enabled by Colloidal Quantum Dots

Photovoltaic-battery (PV/B) hybrid energy systems have gained global attention due to the depletion of fossil fuels and environmental concerns. PV systems play a crucial role in sustainable power generation as they produce clean, environmentally-friendly energy directly from sunlight. Compared to the first-generation silicon PVs, which are ineffective for wavelengths beyond 1100 nm, and the high-cost second-generation III-V semiconductors, Colloidal quantum dots (CQDs) stand out as a key material in the latest generation of PVs. They offer the advantage of absorbing light in the near-infrared (NIR) range at a significantly lower cost. Current PV/B systems often integrate silicon PVs with lithium-ion batteries or direct photobatteries and have demonstrated reliable performance. Although substantial academic work has focused on NIR CQD-based PVs and batteries, research directions in NIR PV/B hybrid systems remain somewhat disorganized and uneven. This review focus on: (i) providing a detailed analysis of CQDs, including their chemical and physical properties and their applications in NIR PV cells, and (ii) summarizing literature on past and current NIR CQDPVs and batteries that could be used in PV/B systems, synthesizing diverse sources of information. This article seeks to offer new insights and identify potential future research directions for professionals in the field.