A Multilayered Electron Extracting System for Efficient Perovskite Solar Cells

Abstract

Power conversion efficiencies of perovskite solar cells (PSCs) have rapidly increased from 3.8% to a certified 25.2% within only a decade. Eliminating possible recombination losses at the interfaces is essential to further improve both efficiency and stability of this class of emerging photovoltaic technology. Herein, a simple approach for improving the electron extraction of the PC 60 BM electron transport layer (ETL) is presented by sequentially depositing Al:ZnO (AZO) and triphenyl-phosphine oxide (TPPO) on top of it, in a p-in device configuration. The efficiency of the resulting CH 3 NH 3 PbI 3-based solar cell is shown to improve from 14.6%, measured for the control PC 60 BM-only cell, to 17.9% for double-ETL (PC 60 BM/AZO) and 19.2% for triple-ETL (PC 60 BM/AZO/ TPPO)-based devices, respectively. Optimized triple-ETL-based cells exhibit high fill factor of 82%. The combination of electrical and quantum mechanical calculations shows that efficiency improvement is attributed to reduced trapassisted recombination at the interface and better energy level alignment due to chemical interactions between PC 60 BM, AZO, and TPPO. Moreover, it is shown that the use of multilayer ETL results in better device stability (T 80 ≈ 800 h) under constant illumination. This work opens new possibilities for inexpensive highly efficient and stable multilayered contacts for PSCs by combining organic small molecules and metal oxides.

Improved Photovoltaic Performance of CsPbI2Br Perovskite Films via Bivalent Metal Chloride Doping

“…We further investigated charge-transport properties of PSCs with and without SrCl 2 by using TPV measurements. The TPV curve revealed that incorporation of SrCl 2 increased the charge-carrier lifetime (Figure 6C), indicating a decrease in the undesired charge-carrier recombination (Seitkhan et al, 2020). As shown in Supplementary Figure S4, the ideality factor (m) was measured to evaluate the recombination process in PSCs.…”

Efficient Hybrid Amorphous Silicon/Organic Tandem Solar Cells Enabled by Near‐Infrared Absorbing Nonfullerene Acceptors

“…For these devices, a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) hole-transport layer and Nb-TiO 2 +BCP electrontransporting bilayer were used, as demonstrated elsewhere. [27,28] This blend of PTB7-Th:IEICO-4F was selected over newer, higher efficiency blends such as PM6:Y6 so as not to limit the current of the tandem device resulting from PM6:Y6's blueshifted absorption edge. A PM6:Y6-containing device was measured beneath a semitransparent a-Si:H device to simulate its use in a tandem structure (Figure S2, Supporting Information).…”

Inorganic top electron transport layer for high performance inverted perovskite solar cells

“…16, Top ETL is an irreplaceable layer for high performance inverted PSC and inevitably resolve the device stability. 3,6,29,34,42,45,63,65,71,81, Therefore, high stability of top ETL will enhance the stability of PSCs and promote the device commercialization.…”

“…[3][4][5] As an important functional layer in high performance inverted PSC, electron transport layer on top of perovskite film (namely top ETL) play an irreplaceable role. Known to be a star ETL, fullerene and it derivative such as [6,6]phenyl-C61-butyric acid methyl ester (PCBM) has been widely used in inverted PSCs, exhibiting negligible hysteresis. [6][7][8][9][10] However, difference between the Fermi level of PCBM and the work function of Ag electrode often results in Schottky barrier at their interface, 11 leading to charge carrier recombination and high series resistance (R S ) and thus low PSC performance.…”

“…Known to be a star ETL, fullerene and it derivative such as [6,6]phenyl-C61-butyric acid methyl ester (PCBM) has been widely used in inverted PSCs, exhibiting negligible hysteresis. [6][7][8][9][10] However, difference between the Fermi level of PCBM and the work function of Ag electrode often results in Schottky barrier at their interface, 11 leading to charge carrier recombination and high series resistance (R S ) and thus low PSC performance. To address these issues, inorganic top ETLs have been used due to their advantages such as good optical and electrical properties, low cost, facile synthesis, controllable properties, and so forth.…”