Interface passivation using diketopyrrolopyrrole-oligothiophene copolymer to improve the performance of perovskite solar cells

The unprecedented increase in power conversion efficiency (PCE) of low-cost organo-inorganic halide perovskite solar cells (OIHPSCs) toward its Shockley-Queisser limit intriguingly has prompted researchers to investigate the disadvantages of these devices. The issue of operational stability is the main hurdle challenging the way forward for commercialization. To address this, various engineering processes like composition, additives, anti-solvents, bulk and interface passivation, and deposition techniques have been widely applied to manage both extrinsic and intrinsic factors that induce degradation of the OIHPSCs. In this work, we employed interface passivation, which is an efficient approach to reduce nonradiative recombination. An ultrathin layer of electron donor diketopyrrolopyrrole-oligothiophene copolymer (DPP860) was applied as an interface passivator between the photoactive layer and [6,6]-phenyl C61 butyric acid methyl ester (PCBM). The role of the interface passivation on optoelectronic properties of the OIHPSCs was assessed using current density versus voltage (J-V) characteristics, photoluminescence spectroscopy and time-resolved photoluminescence spectroscopy. The findings show devices treated with DPP860 exhibit enhanced current density (Jsc) and fill factor, attributing for suppressed nonradiative recombination. Moreover, it shows relative improvement in the stability of the device. The results of this finding reveal that using oligothiophene copolymer can enhance the photovoltaic performance and the stability of inverted OIHPSCs in the ambient environment. The effect of an ultrathin layer of diketopyrrolopyrrole-oligothiophene copolymer (DPP860) interface passivator between the photoactive perovskite layer and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in improving the photovoltaic performance of the perovskite solar cell. image