Tin oxide (SnO 2 ) has been reported as a promising electron transport layer (ETL) for planar heterojunction perovskite solar cells (PSCs). This work reports a low temperature solution-processed bilayer SnO 2 as an efficient ETL in gas-quenched planar-heterojunction methylammonium lead iodide (MAPbI 3 ) perovskite solar cells. SnO 2 nanoparticles were employed to fill the pin-holes of sol−gel SnO 2 layer and form a smooth and compact bilayer structure. The PCE of bilayer devices has increased by 30% compared with sol− gel reference device and the J sc , V oc , and FF has been improved simultaneously. The superior performance of bilayer SnO 2 is attributed to the reduced current leakage, enhanced electron extraction characteristics, and mitigated the trapassisted interfacial recombination via X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), and space-charge limited current−voltage (SCLC) analysis.

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The current work reports the lithium (Li) doping of a low-temperature processed zinc oxide (ZnO) electron transport layer (ETL) for highly efficient, triple-cation-based MAFARbPbI (MA: methylammonium, FA: formamidinium, Rb: rubidium) perovskite solar cells (PSCs). Lithium intercalation in the host ZnO lattice structure is dominated by interstitial doping phenomena, which passivates the intrinsic defects in ZnO film. In addition, interstitial Li doping also downshifts the Fermi energy position of Li-doped ETL by 30 meV, which contributes to the reduction of the electron injection barrier from the photoactive perovskite layer. Compared to the pristine ZnO, the power conversion efficiency (PCE) of the PSCs incorporating lithium-doped ZnO (Li-doped) is raised from 14.07 to 16.14%. The superior performance is attributed to the reduced current leakage, enhanced charge extraction characteristics, and mitigated trap-assisted recombination phenomena in Li-doped devices, thoroughly investigated by means of electrochemical impedance spectroscopy (EIS) analysis. Li-doped PSCs also exhibit lower photocurrent hysteresis than ZnO devices, which is investigated with regard to the electrode polarization phenomena of the fabricated devices.

Inorganic cesium lead triiodide (CsPbI 3 ) perovskite materials are becoming increasingly attractive for use in perovskite/silicon tandem solar cells, due to their almost ideal band gap energy ( E g ) of about 1.7 eV. To be useful as photovoltaic absorbers, the CsPbI 3 must form the cubic or black phase (α-CsPbI 3 ). To do so at relatively low temperatures, hydroiodic acid (HI) is required as a solution additive. This paper demonstrates CsPbI 3 perovskite solar cells with an efficiency of 6.44%, formed using a HI concentration of 36 μL/mL. This value is higher than the previous most commonly used HI additive concentration. Herein, by undertaking a systematic study of the HI concentration, we demonstrate that the structural, morphological, optical, and electrical properties of CsPbI 3 solar cells, processed with this HI additive concentration, are superior.

Solution-processed organic solar cells (OSCs) have become a promising renewable energy technology in recent years.