Role of silver-PC61BM composite electron transport layer in methylammonium lead iodide solar cell

Abstract

Primary ways to achieve high efficiency in photovoltaics is improving light absorption in the photoactive layer. More light absorption results more number of exciton generation and hence more free charge carrier production therefore high current density is possible in photovoltaics. There is a limitation in optical absorption of semiconductor which depends on semiconductor energy bandgap, absorption coefficient, thickness. For optimized photovoltaic condition all afore mentioned parameters are fixed and hence light absorption. To overcome these limitations, various light capturing mechanisms are adopted in photovoltaics. In those mechanisms, plasmonic is very important methods. Placing metal nanoparticles in the light results in absorption and scattering phenomenon based on metal particle size, shape and photon wavelength. Incorporating suitable size of metal nanoparticles either in photoactive layer, buffer layer or in electrode improves light absorption. In this case, silver nanoparticle (AgNPs) mixed with PC61BM was used as an additional buffer layer which localizes and scatters light along sides reduces series resistance. Capacitance reveals that electron transport layer with AgNPs rearranges distribution of trap state. Addition of AgNPs in electron transport layer brings down sheet resistance of device.