Enhancement of the photovoltaic performance of perovskite solar cells via sono‐synthesis of Al‐doped TiO ₂ as the electron transport layer

Abstract

Summary Nowadays, there is a focus on perovskite solar cells (PSCs) as one of the most efficient photovoltaic systems. This research presents the effect of the fabrication method on the aluminum‐doped titanium dioxide (Al‐doped TiO2) as the electron transport layer for the improvement of photovoltaic performance of mesostructured PSCs. In the initial step, TiO2 sol with different concentrations of Al+3 was prepared using the sol‐gel method in the presence of ultrasonic irradiation with low intensity. The compact TiO2 films (c‐TiO2) were deposited using the spin‐coating method, and after thermal treatment, were used to fabricate PSCs. Structural, optical, morphological, and electrical properties of layers were studied using different characterizations. The results obtained imply that increasing the conductivity of Al‐doped TiO2 layers compared to undoped TiO2 requires an optimal amount of Al dopant. According to the applied optimization, the PSCs achieved the best performance when the Al dopant concentration was 1 wt%. Therefore, the best device containing 1 wt% Al‐doped TiO2 film showed a short‐circuit current density of 24.06 mA/cm2, open‐circuit voltage (Voc) of 0.970 V, and fill factor of 0.67, yielding a power conversion efficiency of 15.34%.

Crystalline porous materials in perovskite solar cells: a mutually beneficial marriage

“…TiO 2 is an n-type semiconductor material with high optical transparency, energy level matching with perovskite, and tunable electronic properties, and it is widely used as the ETL in PSCs. 78 Despite the many advantages of TiO 2 as an ETL, low electrical conductivity, electron mobility, and many oxygen vacancy defects generated on the surface after high-temperature sintering limited its further utilization. 79 ZIF-8 is a three-dimensional porous crystal bridged by tetrahedral Zn ions with 2-methylimidazole as the ligand.…”

Applications of Metal Oxide Charge Transport Layers in Perovskite Solar Cells

“…The doping of Al and In was also significant for the enhancement of carrier mobility and conductivity of SnO 2 and TiO 2 . [102,103] In addition, Sn, [104,105] N, Cs, [106] Cl, [107] F, [69,108] and other main group elements were used in doping ETL to regulate the electrical conductivity, defect states, and energy band structure of ETL as well. Furthermore, partial doping could also improve the contact interface between perovskite and ETL, resulting in larger average grain size and better crystallinity of perovskite.…”

Catalyzing the Affordability of Perovskite Solar Cells with Aluminum-Modified Cubic Titania

“…On the other hand, doping metal impurities into the TiO 2 matrix alters the band-edge position of TiO 2 , which also enhances the charge separation at the perovskite/ETL junction. 29 Besides, doping Al in the TiO 2 lattice passivates the bulk electron trap (or oxygen vacancies) and suppresses the recombination of carriers at their surface, improving the respective devices' performance. Though there are some reports on applying Al-TiO 2 in PSCs, the application of Al-TiO 2 nanocubes in PSCs has not yet been examined.…”

“…Since transmittance is the crucial property of ETM, Al is the best choice for dopant in the TiO 2 matrix. On the other hand, doping metal impurities into the TiO 2 matrix alters the band-edge position of TiO 2 , which also enhances the charge separation at the perovskite/ETL junction . Besides, doping Al in the TiO 2 lattice passivates the bulk electron trap (or oxygen vacancies) and suppresses the recombination of carriers at their surface, improving the respective devices' performance.…”