# Luminescence Materials for Dye-Sensitized Solar Cells: Advances and Directions
## 1 Introduction
They are used in various niche markets such as portable electronics (powering of cell phones and cameras), building-integrated photovoltaics (BIPV), and off-grid power systems. However, despite their advantages, DSSCs still face several challenges and gaps that hinder their widespread adoption and commercialization. One of the main challenges is the stability of the dye used in these cells, as many organic dyes degrade rapidly under prolonged exposure to sunlight, limiting the cell's lifespan and efficiency [12; 13]. Additionally, the low conversion efficiency of DSSCs compared to other types of solar cells, such as silicon-based solar cells, remains a major gap that needs to be addressed to enhance the advancement of DSSCs in the market [14; 15]. Another significant challenge of DSSCs is their scalability and manufacturing processes [16; 17]. The complex and delicate nature of assembling DSSCs makes mass production difficult and costly, hindering their commercial viability [18; 19]. Due to the problem of the efficiency and stability of the DSSCs, ongoing research continues to focus on addressing these challenges and exploring new materials and cell architectures to further improve performance [20]. The performance of conventional DSSCs is limited by factors such as narrow absorption spectra and charge recombination losses, which hamper the device's performance. The energy loss in the device encompasses two ways: the first is the charge carrier recombination, which occurs during the electron transport that leads to photoelectron loss, thereby generating a weak photocurrent. The second is the spectral mismatch between the solar irradiation and the dye, which leads to the thermalization of the device by photons of high energy. Current efforts to improve the DSSC performance focus on engineering the nanostructured photo-anode\" with luminescent materials [21; 22; 23; 24; 25; 26; 27; 28]. The need to develop strong luminescent materials and approaches to improve the DSSCs' performance is crucial [29; 30; 31; 32; 33; 34; 35; 36]. They have good absorption, especially in the UV and NIR wavelengths where the DSSC has a low absorption of light, and they emit visible wavelengths, where the dye sensitizers have effective light absorption [37; 38; 39; 40]. The emittedphotons can be re-absorbed by the DSSC device to enhance the light harvesting efficiency of the cells. Basically, there is a gap in research concerning the exploration of alternative luminescent nanomaterials that can extend the absorption spectrum of DSSCs into the UV and near-infrared (NIR) ranges while simultaneously improving charge carrier dynamics and reducing recombination losses. The commonly used dye sensitizers have absorption band ranging from around 400-600 nm, which shows that photons \(<\)400 nm and \(>\)600 nm are not absorbed by the dye-sensitizers. The need to extend the absorption spectrum of the device to the UV and NIR is crucial to address such spectral mismatch in order to convert the incidence photons in such regions into usable energy [41; 42; 43; 44]. In this review, three luminescent materials, namely down-conversion, up-conversion and quantum dots were elucidated, each contributing to the optimization of the DSSCs due to the good optical properties and wide absorption spectrum in the region where the DSSC has a weak spectral responsivity. The article is composed of the following sections: Section 1 introduces the paper. Section 2 elaborates the fundamental principles of DSSC. Section 3 highlights the methods. The luminescent materials in DSSCs are deliberated in Section 4. Section 5 expounds the discussion based on challenges and recommendations of the luminescent materials in DSSCs. Finally, Section 6 concludes the paper.