Tuning Hole Transport Layer Using Urea for High‐Performance Perovskite Solar Cells

Abstract

Interface engineering is critical to the development of highly efficient perovskite solar cells. Here, urea treatment of hole transport layer (e.g., poly(3,4-ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS)) is reported to effectively tune its morphology, conductivity, and work function for improving the efficiency and stability of inverted MAPbI 3 perovskite solar cells (PSCs). This treatment has significantly increased MAPbI 3 photovoltaic performance to 18.8% for the urea treated PEDOT:PSS PSCs from 14.4% for pristine PEDOT:PSS devices. The use of urea controls phase separation between PEDOT and PSS segments, leading to the formation of a unique fiber-shaped PEDOT:PSS film morphology with well-organized charge transport pathways for improved conductivity from 0.2 S cm −1 for pristine PEDOT:PSS to 12.75 S cm −1 for 5 wt% urea treated PEDOT:PSS. The urea-treatment also addresses a general challenge associated with the acidic nature of PEDOT:PSS, leading to a much improved ambient stability of PSCs. In addition, the device hysteresis is significantly minimized by optimizing the urea content in the treatment.order to overcome the reactivity issue of the acidic PEDOT:PSS with the plastic substrates. Therefore, we expect this technology to be expanded for addressing the stability and performance issues of perovskite solar cells.

Encapsulation of Printable Mesoscopic Perovskite Solar Cells Enables High Temperature and Long‐Term Outdoor Stability

“…Doping the typical perovskite absorber with cesium (Cs) and rubidium (Rb), or constructing layered perovskites can improve the thermal and moisture stability. Tuning or replacing the organic charge transport layers such as 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxy‐phenylamine)‐9,9′‐spirobifluorene (Spiro‐OMeTAD) and [6,6]‐phenyl‐C61‐butyrica acid methyl ester (PCBM) can effectively enhance the stability of PSCs under various conditions . Employing modifiers to protect or stabilize the interfaces has also played an essential role in achieving stable PSCs …”

Tailored PEDOT:PSS hole transport layer for higher performance in perovskite solar cells: Enhancement of electrical and optical properties with improved morphology

“…Approaches modifying the PEDOT:PSS layer to achieve higher efficiency in PSCs mostly focused on doping [21][22][23][24] or adding interfacial layer [25][26][27][28][29][30][31][32] . Solvent-only treatments have also been considered as an effective method to modify PEDOT:PSS, which till now has been focused only on single step treatment.…”

Investigating ultrafast carrier dynamics in perovskite solar cells with an extended π-conjugated polymeric diketopyrrolopyrrole layer for hole transportation

“…9 Another very common HTM, PEDOT:PSS was treated with urea which controls phase separation between PEDOT and PSS segments with better morphology and thus gives 18.8% PCE. 10 On a similar note, ITO free PSCs were fabricated using plasma treated PEDOT:PSS with an efficiency of 10.5%. 11 The removal of PSS in PEDOT:PSS provides a PCE of about 18.18% due to increase in perovskite crystal grain size.…”