Light-weight solar panels have great potentials to increase the installation amount of the solar power generation systems because it can be set-up the photovoltaics to the location of difficult to install, for example, on the wall of building and on the roof of weak building such as carport and prefabricated buildings.

Perovskite solar cells (PSCs) are one of the candidates of the ultra-light photovoltaics from their bendable characteristics of the perovskite layers for potentials of the film-type of solar cells. PSCs also can be manufactured by layering of electron and hole transport materials, and the organic-metal-halide perovskite materials as the intermediate layer by coating and printing. This fabrication processes are expected to lead the low-cost photovoltaics. In addition, higher than 20% power conversion efficiency of PSCs has been reached in the small area cells about 1 cm², and they are expected to become next-generation solar cells that enable high efficiency and low cost. However, the practical application of the perovskite solar cells requires the long-term durability and development of the layers coating processes that enable mass production. In this presentation, it will be introduced that the materials development and interface engineering to overcome the challenges to commercialization of PCS.

The hole-transporting material (HTM) is an important component of perovskite solar cells (PSCs) and the most frequently used HTM is Spiro-OMeTAD. In common, Spiro-OMeTAD requires dopants such as Li(TFSI) to realize high power conversion efficiencies (PCEs). However, these dopants cause severe instability issues in PSCs. To overcome this adverse effect from the dopants in HTM, we collaborate with Nippon Fine Chemical Co.,LTD and developed new HTM, SF48 (figure 1), which do not require the dopants. The PSC with non-doped SF48 exhibited a high PCE of 18%, which was comparable to that of the reference PSCs with doped Spiro-OMeTAD. In addition, the thermal stability of SF48 at 85 °C in air was superior to that of Spiro-OMeTAD, both with and without dopants.[1]

On the other hand, hole transporting self-assembled monolayer (SAM) has been developed and it showed better solar cell performances than the ordinally HTM. SAM has the benefits to prepare hole transport layer on the highly-roughness surfaces and the bended surfaces. To further improve the performance of the PSCs with SAMs, it must investigate that the relationship between molecular structure and solar cell performances. we developed the new SAM materials which including the typical additional groups. Then, the solar cell performances are compared with the SAMs including different structures.