Improved Performance of Perovskite Solar Cells by Suppressing the Energy-Level Shift of the PEDOT:PSS Hole Transport Layer

Abstract

In inverted architectures of perovskite solar cells (PSCs), poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate) (PEDOT:PSS) has been widely used as the hole transport layer (HTL). An issue occurring in such PSCs is that the hole transport level of PEDOT:PSS shifts upward since methylammonium iodide (MAI) used for the perovskite structure organization interacts with the underlying PEDOT:PSS HTL as a reducing agent, which impedes hole extraction and therefore lowers the performance of PSCs. To overcome this issue, we demonstrate a way of adding tetraethoxysilane (TEOS) into a water-based PEDOT:PSS solution. The HTL spin-coated from the solution contains PEDOT:PSS, which is blended with siloxanes because the polymerization of TEOS takes place via the hydrolysis reaction. This siloxane blending suppresses the MAI-induced reducing reaction and upward energy-level shift of PEDOT:PSS. Using the siloxane-blended PEDOT:PSS HTL in PSCs leads a ∼1.3-fold increase in power conversion efficiencies of iodide-based PSCs from the original ∼10.58% to ∼13.65%.

Efficient Perovskite Light‐Emitting Diodes with a Siloxane‐Blended Organic Hole Transport Layer

“…[ 50 ] Blending PEDOT:PSS with TEOS impedes the detrimental chemical interaction with methylammonium iodide in perovskite solar cells. [ 38 ] However, TEOS has never been used to make an organic HTL insoluble in perovskite LEDs as we demonstrated in this study.…”

“…We recently reported that using a siloxane‐blended PEDOT:PSS film in inverted perovskite solar cells suppressed the detrimental chemical interaction with methylammonium iodide and, therefore, improved photovoltaic performance. [ 38 ] The actual content of siloxane in the PEDOT:PSS film was much lower than the apparent content used for a spin‐coating solution. [ 38 ] Additionally, measuring the polymerization degree of the siloxane in the PVCz films was very difficult using size exclusion chromatography or static light scattering because the siloxane was unable to be removed from the substrate surface.…”

“…[ 38 ] The actual content of siloxane in the PEDOT:PSS film was much lower than the apparent content used for a spin‐coating solution. [ 38 ] Additionally, measuring the polymerization degree of the siloxane in the PVCz films was very difficult using size exclusion chromatography or static light scattering because the siloxane was unable to be removed from the substrate surface.…”

Efficient and Stable Inverted Perovskite Solar Cells Using Donor–Acceptor–Donor Small Molecules to Tuning NiOx/Perovskite Interfacial Microstructure

“…Hole transport materials such as poly(3,4‐ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), [ 10,11 ] poly‐bis (4‐phenyl) (2,4,6‐trimethylphenyl) amine (PTAA), [ 12,13 ] poly (3‐hexylthiophene‐2,5‐diyl) (P3HT), [ 14,15 ] and nickel oxide (NiO x ) [ 16,17 ] are commonly used in inverted structures. Inorganic hole transport materials NiO x have received extensive attention due to its low price, high stability, large bandgap, and ease of mass production, compared with the high price and poor stability of organic hole transport materials.…”

“…Currently, widely studied device structures are divided into inverted (p-i-n) structure and formal (n-i-p) structure, among which the inverted structure is favored by people due to its high stability, low hysteresis, low fabrication cost, and low-temperature fabrication. [6][7][8][9] Hole transport materials such as poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), [10,11] poly-bis (4phenyl) (2,4,6-trimethylphenyl) amine (PTAA), [12,13] poly (3-hexylthiophene-2,5-diyl) (P3HT), [14,15] and nickel oxide (NiO x ) [16,17] are commonly used in inverted structures. Inorganic hole transport materials NiO x have received extensive attention due to its low price, high stability, large bandgap, and ease of mass production, compared with the high price and poor stability of organic hole transport materials.…”