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

Abstract

The optimization of thickness and surface roughness of the TiO 2 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, TiO 2 pastes synthesized with various concentrations under hydrothermal conditions were utilized to deposit the TiO 2 films of tunable porosities as the ETLs of PSCs. Also, the PSCs were fabricated with a structure of FTO/block-TiO 2 (b-TiO 2 )/m-TiO 2 /CH 3 NH 3 PbI 3 (MAPbI 3 )/CuInS 2 (CIS)/carbon as a low-cost architecture. Moreover, the effect of the TiO 2 paste concentration was studied on the performances of PSCs under fully ambient conditions. The optimal TiO 2 layer was constructed with 20 wt% TiO 2 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% TiO 2 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% TiO 2 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% TiO 2 paste caused ∼163% enhancement in the PCE of the device. Consequently, it could be suggested for application in fabrication of cost-effective and large scale PSCs. • Perovskite solar cells (PSCs) were fabricated by TiO 2 pastes of diverse concentrations. • Surface roughness and thickness of the TiO 2 electron transporting layers were optimized. • The optimal concentration of the mesoporous TiO 2 film was 20 wt%. • The highest efficiency (13.09%) was measured for the cell containing 20 wt% TiO 2 . • The champion device displayed FF = 0.64, J SC = 20.80 mA cm −2 and V OC = 0.98 V.