Book excerpt: Here, we show a new diketopyrrole based polymeric hole-transport material (PBDTP-DTDPP, (poly[[2,5-bis(2-hexyldecyl)-2,3,5,6-tetrahydro-3,6-dioxopyrrolo[3,4- c ]pyrrole-1,4-diyl]- alt -[[2,2′-(4,8-bis(4-ethylhexyl-1-phenyl)-benzo[1,2- b :4,5- b ′]dithiophene)bis-thieno[3,2- b ]thiophen]-5,5′-diyl]])) for application in perovskite solar cells. The material performance was tested in a solar cell with an optimized configuration, FTO/SnO 2 /perovskite/PBDTP-DTDPP/Au, and the device showed a power conversion efficiency of 14.78%. The device charge carrier dynamics were investigated using transient absorption spectroscopy. The charge separation and recombination kinetics were determined in a device with PBDTP-DTDPP and the obtained results were compared to a reference device. We find that PBDTP-DTDPP enables similar charge separation time (