I think because of the problems with the liquid electrolyte, the DSSCs are developed to all solid state perovskite solar cell structure for easier handing and manufacturing in addition to the presence of more alternatives for the hole transport layers, which is an electrolyte in the DSSCs.
Ya now the DSSC is modified into Pervoskite solar cells. The new trend in PSC is developing the lead free electrolytes for high performance and optimizing its fabrication techniques.
Perfectly it is a good question, new trends in DSSC that includes synthesis of new dyes, new raw materials used in photo-anode and cathode, high conductivity and stability of an electrolyte as well how can use the quantum chemistry to simulate the work of DCCs .
Added with the link provided by Adriana, one may refer to the following papers/book:
[1] Grätzel, M. (2003). Dye-sensitized solar cells. Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 4(2), 145-153.
[2] Hagfeldt, A., Boschloo, G., Sun, L., Kloo, L., & Pettersson, H. (2010). Dye-sensitized solar cells. Chemical reviews, 110(11), 6595-6663.
[3] Kalyanasundaram, K. (Ed.). (2010). Dye-sensitized solar cells. EPFL press.
[4] Hagfeldt, A., & Vlachpoulos, N. (2018). Dye-sensitized solar cells. In The Future of Semiconductor Oxides in Next-Generation Solar Cells (pp. 183-239).
[5] Zhang, J., Freitag, M., Hagfeldt, A., & Boschloo, G. (2018). Solid-State Dye-Sensitized Solar Cells. In Molecular Devices for Solar Energy Conversion and Storage (pp. 151-185). Springer, Singapore.