Inhibiting Interfacial Diffusion in Heterojunction Perovskite Solar Cells by Replacing Low‐Dimensional Perovskite with Uniformly Anchored Quaternized Polystyrene

Abstract

Surface heterojunction has been regarded as an effective method to improve the device efficiency of perovskite solar cells. Nevertheless, the durability of different heterojunction under thermal stress is rarely investigated and compared. In this work, benzylammonium chloride and benzyltrimethylammonium chloride are utilized to construct 3D/2D and 3D/1D heterojunctions, respectively. A quaternized polystyrene is synthesized to construct a three‐dimensional perovskite/amorphous ionic polymer (3D/AIP) heterojunction. Due to the migration and volatility of organic cations, severe interfacial diffusion is found among 3D/2D and 3D/1D heterojunctions, in which the quaternary ammonium cations in the 1D structure are less volatile and mobile than the primary ammonium cations in the 2D structure. 3D/AIP heterojunction remains intact under thermal stress due to the strong ionic bond anchoring at the interface and the ultra‐high molecular weight of AIP. Furthermore, the dipole layer formed by AIP can further reduce the voltage loss caused by nonradiative recombination at the interface by 0.088 V. Therefore, the devices based on the 3D/AIP heterojunction achieve a champion power conversion efficiency of 24.27% and maintain 90% of its initial efficiency after either thermal aging for 400 h or wet aging for 3000 h, showing a great promise for polymer/perovskite heterojunction towards real applications.

Mixed-Dimensional Engineering to Generate a Desirable 2D/3D Heterostructure Perovskite Layer to Record Stable and Efficient Carbon-Based Perovskite Solar Cells

“…In the case of 3D FAPbI 3 , the (001), (111), and (002) and lattice planes are attributed to two prominent diffraction peaks at angles of 14.0, 24.3, and 28.1°, respectively. Additionally, a peak at 7.2° is observed in the XRD pattern of the passivated FAPbI 3 layer with TBACl vapor (2D/3D samples), which may have belonged to the two-dimensional TBA 2 PbI 4 perovskite phase. , As can be seen, the 3D FAPbI 3 phases by employing the vapor treatment step are intensified except for the 2D/3D-220 layer. In the 2D/3D-220 layer, not only 3D perovskite phases have not improved but also a δ-FAPbI 3 phase (11.7°) is formed in it.…”

Towards 26% efficiency in inverted perovskite solar cells via interfacial flipped band bending and suppressed deep-level traps

“…Fig. 1c and d show that PDI treatment successfully reduces the surface contact potential difference (CPD), which means that the surface work function (WF) is decreased () 36 and n-type doping of the upper surface is achieved. W tip and W sample represent the WFs of the tip and the sample, respectively.…”

Improving Thermal Stability of High-Efficiency Methylammonium-Free Perovskite Solar Cells via Chloride Additive Engineering

“…The BA + can compensate for the loss of FA + /Cs + by occupying cubic sites and passivating FA + /Cs + vacancies . Additionally, they may potentially form a 2D phase, improving band alignment and enhancing mechanical properties. , Furthermore, a substantial amount of iodine vacancy defects in the perovskite originates from the volatilization and loss of halide anions while thermally annealing the perovskite film . This leads to the creation of NNR centers, resulting in considerable deficits in V oc .…”