Optimization of TiO2 paste concentration employed as electron transport layers in fully ambient air processed perovskite solar cells with a low-cost architecture

The optimization of thickness and surface roughness of the TiO2 layer as an efficient electron transporting layer (ETL) plays a significant role on the performance improvement of perovskite solar cells (PSCs). In the present investigation, TiO2 pastes synthesized with various concentrations under hydrothermal conditions were utilized to deposit the TiO2 films of tunable porosities as the ETLs of PSCs. Also, the PSCs were fabricated with a structure of FTO/block-TiO2 (b-TiO2)/m-TiO2/CH3NH3PbI3 (MAPbI(3))/CuInS2 (CIS)/carbon as a low-cost architecture. Moreover, the effect of the TiO2 paste concentration was studied on the performances of PSCs under fully ambient conditions. The optimal TiO2 layer was constructed with 20 wt% TiO2 paste concentration, which resulted in the formation of a hole-free, smooth, and compact ETL layer. The champion perovskite solar cell fabricated with the 20 wt% TiO2 paste concentration showed the highest power conversion efficiency (PCE) of 13.09% (J(SC) = 20.80 mA cm(-2), V-OC = 0.98 V and FF = 0.64) but the champion PSC device made with the 10 wt% TiO2 paste exhibited the lowest PCE = 8.05% (J(SC) = 19.83 mA cm(-2), V-OC = 0.91 V and FF = 0.45). These results illustrated that the optimal 20 wt% TiO2 paste caused similar to 163% enhancement in the PCE of the device. Consequently, it could be suggested for application in fabrication of cost-effective and large scale PSCs.

Automated summary

By optimizing the thickness and surface roughness of the TiO2 layer, significant improvements in the performance of perovskite solar cells can be achieved. The use of a 20% TiO2 paste concentration resulted in the highest power conversion efficiency for the fabricated champion PSC device.