Abstract:
Although perovskite solar cells (PSCs) have reached a record
high conversion efficiency of 25.7%, the materials used to fabricate them
invoke costly hole-transporting materials, such as spiro-OMeTAD, and
expensive gold back contacts. The cost of fabrication of a solar cell or any
other practical device is an important issue in their practical applications. In
this study, we describe the fabrication of a low-cost, mesoscopic PSC,
eliminating the use of expensive p-type semiconductors and substituting
them with electronically conducting activated carbon, and the gold back
contact with expanded graphite. The activated carbon hole transporting
material was derived from readily available coconut shells and the expanded
graphite from graphite attached to rock pieces of graphite vein banks. We
drastically reduced the overall cell fabrication cost using these low-cost
materials and added commercial value to discarded graphite and coconut
shells. Under ambient conditions, our PSC gives a conversion efficiency of 8.60 ± 0.10 % at 1.5 AM simulated sunlight. We have
identified the lower fill factor as the limiting factor for the low conversion efficiency. We believe that the lower cost of the materials
used and the deceptively simple powder pressing method would compensate for the relatively lower conversion efficiency in its
practical application.
