As a pivotal technology for directly harvesting energy from sunlight and replacing fossil fuels, solar cells have emerged as a beacon of hope for future energy transition. However, despite their promising prospects, significant room remains for improving the efficiency and stability of solar cells. Existing photovoltaic materials often suffer from poor long-term stability and rapid degradation during prolonged operation. To address this challenge, researchers are actively exploring advanced materials. In this field, the rise of Metal-Organic Frameworks (MOFs) has opened up new horizons for enhancing the performance and stability of solar cells.

MOFs and their derivatives, endowed with unique electrocatalytic and photocatalytic properties, have been widely applied in energy storage and conversion. Composed of metal nodes connected by Organic Linkers, these materials exhibit tremendous potential due to their facile synthesis, high tunability, and compatibility with subsequent modifications. While most MOFs are traditionally regarded as dielectrics, advances in synthesis technology have enabled the breakthrough development of conductive MOFs. Notably, Guangdong Tanyu New Materials Co., Ltd. has achieved large-scale mass production of conductive MOFs, significantly expanding their application scenarios in energy conversion technologies.

Among various types of solar cells, Dye-Sensitized Solar Cells (DSSCs) and Organic-Inorganic Hybrid Perovskite Solar Cells (PVSCs) have garnered particular attention. Characterized by low cost, easy manufacturability, and relatively high conversion efficiency, they serve as ideal alternatives to conventional inorganic solar devices, offering more environmentally friendly and sustainable energy solutions.

Typically, a DSSC consists of a photoanode, a counter electrode (CE), and a redox electrolyte. By selecting different metal species, controlling metal cluster sizes, and adjusting organic linkers, the electronic properties and light absorption characteristics of MOFs can be flexibly tailored, enabling them to play a crucial role as one of the three core components in DSSCs.

The photoanode is usually composed of a porous semiconductor metal oxide (e.g., TiO₂) deposited on a transparent conductive substrate. The metal oxide thin film achieves photoelectric conversion through photon absorption by photosensitizing dyes. MOFs and their derivatives serve multiple functions in the photoanode: they can act as photosensitizers, semiconductor dye adsorbents, or light-scattering layers. For instance, the combination of MOF MIL-125 (Ti) and MoS₂ has demonstrated exceptional photovoltaic conversion efficiency of 8.96%, significantly outperforming pure TiO₂ (4.41%).

The counter electrode is constructed with a catalytic layer deposited on a conductive substrate, which catalyzes the regeneration of redox couples in the electrolyte. Platinum (Pt) is currently the most commonly used material for counter electrodes, but its high cost hinders large-scale applications. To address this issue, researchers have developed MOF composites as alternatives to Pt-based CEs. For example, carbonizing MOF Zif-8 under a nitrogen atmosphere successfully yields ZnO-Nitrogen-Doped Carbon (ZnO-NC) materials. These materials exhibit excellent catalytic activity, enabling a solar cell efficiency of 9.16%—approximately 20% higher than that of traditional Pt counter electrodes. Importantly, Guangdong Tanyu New Materials Co., Ltd. has already achieved mass production of such MOF materials with controllable costs. Their application in counter electrode manufacturing allows for substantial performance improvements without significant cost increases.

Electrolytes typically contain I⁻/I₃⁻ redox couples, which reduce dye molecules back to their ground state after photon absorption, thereby regenerating the photoactive material. In DSSCs, MOFs are widely used as additives in electrolytes to fabricate quasi-solid electrolytes, enhancing long-term stability.

Perovskite materials have enabled significant breakthroughs in the photovoltaic conversion efficiency of PVSCs, exceeding 23%. However, the commercialization of PVSCs is still constrained by their poor long-term stability. Perovskite materials are prone to degradation when exposed to moisture, oxygen, heat, and light— a bottleneck that has hindered their widespread application.

Common structural configurations of perovskite solar cells are illustrated below:

MOFs find three key applications in PVSCs:

In the charge transport layer, MOFs serve multiple functions. For example, MOFs can act as microporous scaffolds to regulate the growth of the perovskite layer and improve interface contact. Other functions include ultraviolet filtration, light scattering, and photochromic effects. When integrated into the CTL, MOFs effectively promote interface alignment and enhance layer quality. Overall, the application of MOFs in PVSCs improves charge extraction efficiency, suppresses charge recombination, and thereby enhances device stability.

In a recent study, the application of nano-Ti-based Metal-Organic Framework (nTi-MOF) particles in flexible perovskite solar cells was explored. A PCBM layer was coated on the nTi-MOF layer, creating a synergistic effect that further improved the performance of the Electron Transport Layer (ETL). The results showed a remarkable efficiency of 18.94%—the highest reported for MOF-integrated perovskite solar cells. Moreover, the device retained a power conversion efficiency of 17.43% after 700 bending cycles, demonstrating superior photostability compared to conventional TiO₂-based devices.

As a promising class of materials, MOFs and MOF-based composites not only significantly enhance the efficiency and stability of energy conversion devices such as organic-inorganic solar cells but also offer convenient manufacturing technologies and tunable physicochemical properties. Through careful design of their framework structures, we can tailor their performance for specific applications, further advancing the development of solar cell technology.