The sharp increase of research passion in the new-generation solar cells in recent years has resulted in a new trend in combining multiple types of energy devices in a single device. In view of the enhanced and/or diversified function of integrated devices, as compared with conventional devices with limited performance or sole applicability, many integrated power packs have been widely developed by combining different devices, such as a silicon solar cell (SSC), Cu(In,Ga)(Sn,Se)₂ (CIGS), organic solar cell (OSC), dye-sensitized solar cell (DSSC), perovskite solar cell (PSC), lithium-ion battery (LIB), nanogenerator (NG), supercapacitor (SC), photoelectrosynthetic cell (PESC), and electrolysis cell (ELC), into one unit. In this Review, with a particular emphasis on their recent advances, we cover the integrated solar cell device research in a broad sense and provide an overview of state-of-the-art progress on the integrated solar cell devices based on DSSC and PSC, such as DSSC/LIB, DSSC/SC, DSSC/NG, DSSC/LIB/NG, PSC/OSC, PSC/CIGS, PSC/PSC, PSC/SSC, SSC/SC, PSC/SC, OSC/SC, DSSC/PESC, PSC/PESC, and PSC/ELC, for energy harvesting and storage that are significantly important for self-powering systems and portable/wearable electronics. Finally, the challenges and future outlooks in this promising photovoltaic (PV) field are featured on the basis of current development.

Platinum (Pt)-free counter electrodes (CEs) are economical alternative components of dye-sensitized solar cells (DSSCs) that have attracted much interest and become the focus of research, with an increasingly large number of scientific papers published in the last two decades. The development of these CE materials was driven mainly by desires to overcome the disadvantages of Pt, as follows: high cost, scarcity, corrosion by the I₃ ⁻/I⁻ redox couple electrolyte, and mismatch or non-effectivity in the I-free redox couple electrolyte. Although much more is now known about the principal physicochemical processes that occur during CE operation of the DSSC, the stability issues associated with CEs have not been matched by the exponential increase in CE research effort. This raises questions regarding the stability of the CEs whether the present research is sufficiently addressing the stability issues that limit DSSC performance. This review attempts to identify some of the key techniques that evaluate CE stability in DSSCs through a selective presentation of recent research highlights. Classical approaches could effectively assess the probability of using alternative Pt-free CE materials for commercial application, which offer strategies to overcome the current stability stalemate.

The sustainable production of green hydrogen via water electrolysis necessitates cost-effective electrocatalysts. By following the circular economy principle, the utilization of waste-derived catalysts significantly promotes the sustainable development of green hydrogen energy. Currently, diverse waste-derived catalysts have exhibited excellent catalytic performance toward hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water electrolysis (OWE). Herein, we systematically examine recent achievements in waste-derived electrocatalysts for water electrolysis. The general principles of water electrolysis and design principles of efficient electrocatalysts are discussed, followed by the illustration of current strategies for transforming wastes into electrocatalysts. Then, applications of waste-derived catalysts (i.e., carbon-based catalysts, transitional metal-based catalysts, and carbon-based heterostructure catalysts) in HER, OER, and OWE are reviewed successively. An emphasis is put on correlating the catalysts’ structure–performance relationship. Also, challenges and research directions in this booming field are finally highlighted. This review would provide useful insights into the design, synthesis, and applications of waste-derived electrocatalysts, and thus accelerate the development of the circular economy-driven green hydrogen energy scheme.

To advance the progress of photoelectrolysis, various promising devices integrated with p- and n-type photocatalysts and dye sensitized photoelectrodes have been systematically studied. This review discusses, from theory to practice, an integration strategy for state-of-the-art dye sensitized solar cells (DSSCs) with potential p- and n-type photo-electrocatalysts or directly with dye sensitized photoanodes and cathodes for hydrogen and oxygen production through water splitting. Thorough insight into the theoretical approach which systematically drives the photoelectrolysis reaction directly or in a coupled mode, with diverse configurations of DSSCs and other photovoltaic (PV) cells, is crucial to understand the underlying fundamental concepts and elucidate trends in such reactions, and will serve as a guide to design new electrocatalysts and their integration with new PV devices, while simultaneously underlining major gaps that are required to address the challenges. Likewise, challenges, opportunities and frontiers in tandem and hybrid perovskite electrolysis processes are also discoursed in the present tutorial review. We illustrate our analysis by encompassing these integrated systems to photo-electrolysis, artificial photosynthesis such as CO₂ conversion into value-added chemical reduction-products, where advancements in new catalysts and solution-processed inexpensive PV devices can certainly enrich the overall performance of the renewable production of solar fuels, including solar driven carbonaceous fuels.