18% High-Efficiency Air-Processed Perovskite Solar Cells Made in a Humid Atmosphere of 70% RH

Abstract

Despite the advanced progress in power conversion efficiency (PCE), developing air‐processed high‐efficiency perovskite solar cells (PVSCs) for future commercialization is still challenging. Here, we report that besides the general wisdom of the effect of moisture, oxygen in air has a severe impact on the quality of the solution‐deposited perovskite films. Interestingly, as opposed to moisture that induces fast crystallization of PbI2 upon deposition, oxygen exacerbates the wettability of the PbI2 solution on the substrates. We find that simply preheating the substrate and PbI2 solution a fully covered and uniform PbI2 film deposited in air can be obtained. This is possibly due to the increased vapor pressure of the solvent at higher temperatures to reduce the ingress of oxygen and moisture during the PbI2 deposition. Using this simple method, an air‐processed PVSC made under a humid atmosphere of 70% RH has a record PCE of 18.11%. Our work not only reveals the origin of the detrimental effects on perovskite film formation in ambient air, but also provides a simple practical strategy to develop air‐processed high‐efficiency PVSCs for future commercialization.

A prenucleation strategy for ambient fabrication of perovskite solar cells with high device performance uniformity

“…More significantly, this outstanding efficiency comes at an extremely low cost since the perovskite solar cells can be obtained by a solution-based fabrication process, triggering a global competition to translate the brilliant perovskite materials to innovative technologies [8][9][10][11] . However, researchers quickly found that the performance of PVSCs is quite sensitive to humidity, oxygen and solvent vapors, severely restricting the fabrication condition of such solar cells [12][13][14] . Normally, the oxygen and H 2 O should be below the ppm level to avoid their perceptibly negative effects on the perovskite based devices.…”

Fabrication of Efficient and Stable Perovskite Solar Cells in High‐Humidity Environment through Trace‐Doping of Large‐Sized Cations

“…[3,4] Nowadays, the most significant methods for improvinge nvironmental stability are the exploration of new perovskite materials with better intrinsic stabilityand the development of novel preparation processes, including additive engineering strategies, [5][6][7] interface engineering, [8][9][10][11][12] andp rocess optimization. [17,18] Many studies have revealed that improving perovskite film morphology and crystalline quality is an effective strategy for enhancing the intrinsic stabilityo fp erovskite materials, providing more possibilities for highly efficient and stable devices. This becomes astumbling block for their commercialization.…”

“…For example, the addition of SCN À ,L ewis acid, or trimethylammonium chloride into the perovskite precursor can increase the grain size and device performance significantly. [17,26,27] Besides, the use of al ead thiocyanate [Pb(SCN) 2 ]p recursora llowed the preparationo fh igh-quality CH 3 NH 3 PbI 3Àx (SCN) x perovskite films under high-humidity conditions. [22][23][24] However,t hesef acile solution processes normally need to be conducted in an itrogen glovebox.…”

“…This becomes astumbling block for their commercialization. [17,18] Many studies have revealed that improving perovskite film morphology and crystalline quality is an effective strategy for enhancing the intrinsic stabilityo fp erovskite materials, providing more possibilities for highly efficient and stable devices. For example, the addition of SCN À ,L ewis acid, or trimethylammonium chloride into the perovskite precursor can increase the grain size and device performance significantly.…”

“…[25] Preheating the substrate hasa lso been discovered to play ap redominant role in determining photovoltaic performance under an atmospheric environment. [17,26,27] Besides, the use of al ead thiocyanate [Pb(SCN) 2 ]p recursora llowed the preparationo fh igh-quality CH 3 NH 3 PbI 3Àx (SCN) x perovskite films under high-humidity conditions. [28] Although the Solution-processed organic-inorganic lead halide perovskites have shown photovoltaic performance above 23 %, attracting great attention.…”