Highly Efficient Guanidinium‐Based Quasi 2D Perovskite Solar Cells via a Two‐Step Post‐Treatment Process

Abstract

2D perovskites with alternating cations in the interlayer space (ACI) have raised increasing interest in the field of layered 2D perovskite solar cells (PVSCs). Herein, ACI quasi‐2D PVSCs with a chemical formula of C(NH2)3(CH3NH3)4Pb4I13 (n = 4) are fabricated by an antisolvent method assisted by a novel two‐step post‐treatment process, in which guanidinium thiocyanate (GASCN) and MACl (GA = guanidinium, MA = methylammonium) are utilized as post‐treatment reagents, sequentially. With the first‐step post‐treatment by GASCN, the grain gaps within the perovskite films are dramatically diminished, leading to increased alignment and well‐ordered crystal grains. Consequently, the power conversion efficiency (PCE) of the corresponding devices increases by more than 50% (from 8.62% to 13.13%). After the second‐step post‐treatment by MACl, the trap states in the perovskite films are passivated, and as a result the PCE of the PVSCs is further enhanced to 15.27%. This work provides the new method of two‐step post‐treatment for fabrication of high quality 2D PVSC films.

Crystallization Kinetics in 2D Perovskite Solar Cells

“…Among them, the shearing method along the 〈100〉 crystal direction is the most common, and it can form three 2D perovskite phases, Ruddlesedn-Popper (R-P) [53,54] Dion-Jacobson (D-J) [55][56][57] and alternating cations in the interlayer space (ACI). [58][59][60] Their structures are illustrated in Figure 2a. The methods of cutting along the 〈110〉 and 〈111〉 directions are rarely reported in the literature (and they are not discussed here).…”

Present Status and Research Prospects of Tin‐based Perovskite Solar Cells

“… Crystal structure of 2D perovskites a) RP phase (left), DJ phase (right), b) ACI2D perovskite, and (c) B‐ACI (BEA) MA n Pb n X 3 n +1 perovskite. (d) Top‐view SEM images with cross‐sectional SEM images in the inset using 0, 2, 4, 6 mg mL −1 GASCN solution . (a) Reproduced with permission .…”

“…Copyright 2017, ACS Publications. (d) Reproduced with permission . Copyright 2019, WILEY‐VCH Verlag GmbH & Co. KGAA, Weinheim.…”

“…As the GA has played key role for accomplishment of champion PCE for Sn‐based perovskite, this newly proposed method can be a viable option for the enhancement of photovoltaic parameters for Sn‐based perovskites. Figure d shows the top‐view SEM images with cross‐sectional images in the insets of ACI quasi‐2D perovskite films using 0, 2, 4, 6 mg mL −1 GASCN solution …”

Bifunctional Ytterbium (III) Chloride Driven Low‐Temperature Synthesis of Stable α‐CsPbI3 for High‐Efficiency Inorganic Perovskite Solar Cells

“…This process is complex since the water in hydriodic acid solution should be totally removed . Moreover, the defects at the grain boundaries and surface area of perovskite films may serve as carrier recombination centers, which will reduce the open‐circuit voltage ( V oc ) and fill factor (FF) . The defects with a high reactive activity can also accelerate the degradation of the perovskite film when exposed to humid atmosphere.…”