Effect of Different Hole Transport Materials on Recombination in CH3NH3PbI3 Perovskite-Sensitized Mesoscopic Solar Cells
We report on perovskite (CH3NH3)PbI3-sensitized solid-state solar cells using spiro-OMeTAD, poly(3-hexylthiophene-2,5-diyl) (P3HT) and 4-(diethylamino)benzaldehyde diphenylhydrazone (DEH) as hole transport materials with a light to electricity power conversion efficiency of 8.5%, 4.5%, and 1.6%, resp., under AM 1.5G illumination of 1000 W/m2 intensity. Photoinduced absorption spectroscopy shows that hole transfer occurs from the (CH3NH3)PbI3 to hole transport materials after excitation of (CH3NH3)PbI3. The electron lifetime (τe) in these devices are in the order Spiro-OMeTAD > P3HT > DEH, while the charge transport time (ttr) is rather similar. The difference in τe can therefore explain the lower efficiency of the devices based on P3HT and DEH. This report shows that the nature of the hole transport material is essential for charge recombination and elucidates that finding an optimal hole transport material for the perovskite solar cell includes controlling the perovskite/hole transport material interaction. Design routes for new hole transport materials are suggested.
Record created on 2015-07-06, modified on 2016-09-27