Tailoring the Grain Boundaries of Wide‐Bandgap Perovskite Solar Cells by Molecular Engineering

Abstract

Due to the attraction of fabricating highly efficient tandem solar cells, wide‐bandgap perovskite solar cells (PSCs) have attracted substantial interest in recent years. However, polycrystalline perovskite thin‐films show the existence of trap states at grain boundaries which diminish the optoelectronic properties of the perovskite and thus remains a challenge. Here, a one‐step solution‐processing of [ MA0.9Cs0.1Pbfalse(I0.6Br0.4false)3] wide‐bandgap perovskite using phenylhydrazine iodide with amino groups is demonstrated to successfully passivate the trap density within grain boundaries and increase the perovskite grain size. The reinforced morphology and grain boundaries treatment considerably enhanced the power conversion efficiency (PCE) from 12.16% for pristine to 14.63% for the treated devices. This strategy can be easily adopted to other perovskites and help realize highly efficient perovskite solar cells.

Efficient and Stable Wide‐Bandgap Perovskite Solar Cells Derived from a Thermodynamic Phase‐Pure Intermediate

“…[55][56][57] To prepare high-quality perovskite thin films, the most valid strategy was to reduce defects in grain boundaries by retarding the fast crystallization of perovskite. [58,59] In contrast to the methylammonium lead halide, alloying perovskites Cs x FA 1-x Pb(I y Br 1-y ) 3 are hard to coordinate with solvent molecules (such as DMSO, NMP) to DOI: 10.1002/solr.202100906 Wide-bandgap perovskites based on alloying cesium and formamidinium lead mixed halides (Cs x FA 1-x Pb(I y Br 1-y ) 3 ) have received great attention due to their potential application in high-efficiency tandem solar cells. However, the fast crystallization of Cs x FA 1-x Pb(I y Br 1-y ) 3 perovskite films results in a high trap density and hinders the further enhancement of the photovoltaic performance.…”

“…[ 55–57 ] To prepare high‐quality perovskite thin films, the most valid strategy was to reduce defects in grain boundaries by retarding the fast crystallization of perovskite. [ 58,59 ] In contrast to the methylammonium lead halide, alloying perovskites Cs x FA 1– x Pb(I y Br 1– y ) 3 are hard to coordinate with solvent molecules (such as DMSO, NMP) to form stable intermediate adducts, and thus their crystallization is fast during the conventional one‐step process. [ 60 ] On the other hand, the simultaneous introduction of FABr and FAI by interdiffusion annealing in two‐step method suffers from the different kinetic and thermodynamic properties of the reaction of FABr and FAI with the precursor, which leads to the difficulty in the control of well‐defined composition and reproducibility.…”

Mitigating Open-Circuit Voltage Loss in Pb–Sn Low-Bandgap Perovskite Solar Cells via Additive Engineering

“…Charge transfer dynamics of the devices was studied by measuring impedances at the frequency range of 1 Hz to 1 MHz. The results obtained from the measurement were fitted with the commonly used one R–C circuit. − The equivalent circuit and corresponding parameters are provided in Figure S9 and Table S3 in Supporting Information, respectively. The control device demonstrated an R rec of ∼5 KΩ, whereas the 1.5 PEAI devices showed an R rec of ∼12.45 KΩ.…”

Hetero-perovskite engineering for stable and efficient perovskite solar cells

“…[10][11][12][13][14] PSCs have demonstrated outstanding photovoltaic performance and potential in the practical commercialization; however, they are facing serious problems in long-term stability, mainly due to the intrinsic instability of perovskite absorption layers and unstable factors of other functional layers in PSCs. 8,[15][16][17][18] To improve the stability of perovskites, some strategies have been proposed recently, including molecular engineering, [19][20][21][22] interfacial modication, [23][24][25] defect passivation, [26][27][28][29] optimization of transporting layers, 30,31 optimization of electrodes, [32][33][34] device encapsulation, [35][36][37][38] structure optimization, 39,40 the Xiaohua Cheng was born in Shandong province, China, in 1994. She joined BIT in 9/2020 as a PhD candidate in the School of Chemistry and Chemical Engineering and Advanced Research Institute of Multidisciplinary Science (ARIMS).…”