Room-Temperature Solution-Processed n-Doped Zirconium Oxide Cathode Buffer Layer for Efficient and Stable Organic and Hybrid Perovskite Solar Cells

Abstract

In this study, we present a simple and effective method to improve the performance and stability of organic and hybrid perovskite solar cells by the incorporation of solution-processed cetyltrimethylammonium bromide (CTAB)-doped zirconium oxide (ZrO x ) as cathode buffer layer (CBL). This novel n-doped ZrO x CBL possesses several remarkable features, including ease of fabrication without the need for thermal annealing or any other post-treatment, reasonable electrical conductivity (2.9 × 10–5 S cm–1), good ambient stability, effective work function modulation of Ag electrode, relative weak thickness-dependent performance property, and wide applicability in a variety of active layers. Compared with ZrO x CBL without CTAB dopant, CTAB-doped ZrO x can significantly improve the power conversion efficiency (PCE) from 0.57% to 2.48% in organic solar cells based on diketopyrrolopyrrole-thiophene-bezothiadazole low-bandgap polymer (PDPP-TBT):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) blend. With this n-doped ZrO x CBL, organic solar cells based on polythieno­(3,4-b)-thiophene-alt-benzodithiophene (PTB7):PC71BM blend deliver a record high PCE of 9.3%. The effectiveness of this novel CBL also extends to perovskite solar cells, and a high PCE up to 15.9% is demonstrated, which is superior to those of the devices with undoped ZrO x and state-of-the-art CBL zinc oxide nanoparticle film. In addition, this approach is applicable to the development of high-performance semitransparent solar cells. More significantly, the long-term ambient stability of the resulting devices can be secured without the need of rigorous encapsulation.

Interfacial Engineering of Metal Oxides for Highly Stable Halide Perovskite Solar Cells

“…In this work the authors demonstrated how doping ZrO x with CTAB increases its electrical conductivity and improves device performance in comparison with devices applying the bare ZrO 2 oxide. Moreover, the ZrO x ‐based material can be fabricated at room temperature, and the final device shows high stability without the need for rigorous encapsulation . All these novel results suggest that there is still much room for improvement in the functionalization of oxide interfaces, semiconductors or inert scaffolds, for the enhancement of stability in PSCs.…”

“…(n) ITO/NiCo 2 O 4 /perovskite/PC 61 BM:C 60 /ZrAcac/Ag . (o) ITO/PEDOT:PSS/perovskite/PC 61 BM/ZrO x /Ag and ITO/ PEDOT:PSS/perovskite/PC 61 BM/ZrO x ‐CTAB/Ag . (p) ITO/PEDOT:PSS/perovskite/PCBM/C 60 /Ag and ITO/CuNiO/perovskite/PCBM/C 60 /Ag .…”

Recent advances in interfacial engineering of perovskite solar cells

“…PHJ p-i-n PSCs with a typical inverted structure (ITO/ PEDOT:PSS/perovskite/PCBM/metal) are promising for future flexible electronic devices due to their low-temperature processability [26]. It is important that the work functions of the cathode and anode match the quasi-Fermi levels of the active layers to ensure ohmic contact, maximum Voc, and minimal energy barrier for charge extraction to reduce interface carrier recombination [143,144]. Accordingly, low work function metals such as Al (~4.1 eV) or Ca (~2.9 eV) are sometimes used as cathode electrodes in PHJ p-i-n PSCs for efficient electron extraction (tables 1-4).…”

Efficient and Stable Vacuum‐Free‐Processed Perovskite Solar Cells Enabled by a Robust Solution‐Processed Hole Transport Layer

“…[9][10][11] The incomplete coverage of the interfacial layer can cause detrimental effects on devicep erformance and long-term stability. [17][18][19][20][21] Ar epresentative example is poly (3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenes ulfonate) (PSS) anions (PEDOT:PSS), which representst he mostc ommonly used hole transportl ayer (HTL) in p-i-n typeP SCs (device configuration: substrate/anode/HTL/perovskite/electron transport layer (ETL)/ cathode)s of ar. [15,16] To overcomet hese intrinsic materials limitations, an effective approach is to incorporated opants into the host semiconductors (i.e.,d oping) to alter the carrier concentration and thus the electronic conductivity of the materials.…”

“…[15,16] To overcomet hese intrinsic materials limitations, an effective approach is to incorporated opants into the host semiconductors (i.e.,d oping) to alter the carrier concentration and thus the electronic conductivity of the materials. [17][18][19][20][21] Ar epresentative example is poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenes ulfonate) (PSS) anions (PEDOT:PSS), which representst he mostc ommonly used hole transportl ayer (HTL) in p-i-n typeP SCs (device configuration: substrate/anode/HTL/perovskite/electron transport layer (ETL)/ cathode)s of ar. [9,10] The PEDOT:PSS layer possesses several advantages as HTL such as favorable solution processability, high work function, and tunable conductivity.…”