Exceeding 20% Efficiency for Highly Efficient and Stable Inverted Perovskite Solar Cells via Sodium Borohydride Induced Interface Engineering

Abstract

Poly(3,4‐ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) is widely used as a hole transport layer in inverted perovskite solar cells (PSCs). However, due to the serious interface defects, imperfect energy level arrangement, and low hole transfer rate between PEDOT:PSS and perovskite, the realization of efficient and stable inverted PSCs is hindered. Herein, ionic salt sodium borohydride is used as an interfacial modifier between PEDOT:PSS and MAPbI3−xClx. NaBH4 acts as an anchor to bond Pb2+ to the PEDOT:PSS surface and guides the growth of the perovskite. The champion power conversion efficiency (PCE) of the device based on NaBH4‐PEDOT:PSS reaches 20.21%, which is improved by 27.5% compared with the device based on PEDOT:PSS (15.84%). This PCE is one of the highest in inverted PSCs with PEDOT:PSS as the hole transport layer and MAPbI3−xClx as the active layer. The improved device performance is mainly attributed to the reduced valence band edge of PEDOT:PSS which matches better with the HOMO of MAPbI3−xClx, and the hole transfer rate is increased from 2.65 × 1010 to 3.69 × 1010 s−1. The long‐term stability of the optimized device exceeds 1000 h. This work provides a simple and effective strategy to improve the PCE and stability of inverted PSCs, which is a benefit for future popularization.

Synergistic Effect of Sodium Cyanoborohydride in Pb‐Sn Perovskite Solar Cells

“…The diffusion of B 3+ and Na + to the PEDOT:PSS layer contribute to improve the performance of PEDOT:PSS/perovskite interface. [42] The distribution of Na + in the perovskite xlayer could inhibit the migration of halide ions, alleviate the current-voltage hysteresis and improve the operational stability of PSCs. [43] Therefore, SC will not only reside on the upper surface, but also migrate into the bulk phase of perovskite and PEDOT:PSS layer and continue to interact with these functional layers.…”

Advances and Outlook of Boron–Hydrogen Containing Materials for Potential Clean Energy Applications: A Review

“…117,118 Therefore, it becomes critical to reduce ionic vacancies and avoid the volatilization of organic cations, which is very important to enhancing the stability of PSCs. To this end, Wu et al 119 used NaBH 4 as an interfacial modifier between poly(3,4-ethylenedioxythiophene):poly styrene-sulfonate (PEDOT: PSS) and MAPbI 3−x Cl x , where PEDOT:PSS acts as the hole transport layer (Figure 20a). NaBH 4 adsorbs Pb 2+ onto the PEDOT:PSS surface, which promotes perovskite crystal formation and thus modifies interfacial defects, improving the stability and photovoltaic conversion of PSCs.…”

“…(c) J–V curve of inverted PSCs based on PEDOT:PSS and 1-NaBH 4 –PEDOT:PSS films. Reproduced with permission from ref . Copyright 2022, John Wiley and Sons.…”

Efficient and Stable Inverted Perovskite Solar Cell using Potassium Fluoroborate Doped PEDOT:PSS

“…[28] The enhanced optical absorption of the perovskite film can be attributed to the larger grain size and better crystallinity of the perovskite grown on the film. [20,21,28,29] Increased optical absorption leads to the generation of more electron-hole pairs in the perovskite, contributing to improved performance of perovskite solar cells.…”

“…This work provides a simple and effective method to solve the problem of low hole transport in inverted devices with PEDOT:PSS as the hole transport layer. [19][20][21] 2. Results and Discussion The XPS full spectra of PEDOT:PSS and 2-KBF 4 -PEDOT:PSS are presented in Figure 1a.…”