Anti‐Dissociation Passivation via Bidentate Anchoring for Efficient Carbon‐Based CsPbI_2.6Br_0.4 Solar Cells

Abstract

Molecular passivation on perovskite surface is an effective strategy to inhibit surface defect-assisted recombination and reduce nonradiative recombination loss in perovskite solar cells (PSCs). However, the majority of passivating molecules bind to perovskite surface through weak interactions, resulting in weak passivation effects and susceptible to interference from various factors. Especially in carbon-based perovskite solar cells (C-PSCs), the molecular passivation effect is more susceptible to disturbance in subsequent harsh preparation of carbon electrodes via blade-coating route. Herein, bidentate ligand 2,2′-Bipyridine (2Bipy) is explored to passivate surface defects of CsPbI 2.6 Br 0.4 perovskite films. The results indicate that compared with monodentate pyridine (Py), bidentate 2Bipy shows a stronger chelation with uncoordinated Pb(II) defects and exhibits a greater passivation effect on perovskite surface. As a result, 2Bipy-modified perovskite films display a significantly boosted photoluminescence lifetime, accompanied by excellent anchoring stability and anti-dissociation of passivating molecules. Meanwhile, the moisture resistance of the 2Bipy-modified perovskite films is also significantly enhanced. Consequently, the efficiency of C-PSCs is improved to 16.57% (J sc = 17.16 mA cm −2 , V oc = 1.198 V, FF = 80.63%). As far as it is known, this value represents a new record efficiency for hole transport material-free inorganic C-PSCs.

In Situ Growth of a Robust 1D Capping Layer for Stable and Efficient CsPbI3 Perovskite Solar Cells Without Hole Transporter

“…To address such issue, some strategies have been employed, such as element doping, [14,23] additive engineering [24][25][26] and surface modification. [27][28][29][30] Nevertheless, element doping and additive engineering usually face with widened E g , ions aggregation, and lower charge transport, while the effect of surface modification with small molecules on phase structure is very limited. [31][32][33] Regarding organic-inorganic perovskites, it has been widely recognized that in-situ formation of a low dimensional (LD) perovskite capping layer on 3D perovskite is a promising route to enhance chemical and phase stability of the 3D perovskite.…”

Moisture Induced Secondary Crystal Growth Boosting the Efficiency of Hole Transport Layer‐Free Carbon‐Based Perovskite Solar Cells beyond 19.5%

“…[12][13][14] Therefore, HTL-free carbon-based perovskite solar cells (C-PSCs) show promising commercial application potential. [15][16][17][18][19][20][21][22][23] However, the reported highest PCE of C-PSCs is only 19.06% to date, [21] which lags far behind the traditional metal electrode-based ones and needs further improvement.…”

Interfacial dipole engineering in all-inorganic perovskite solar cells

“…18 As p is a vector, its magnitude determines the magnitude of D, and its direction determines the sign of D. A positive dipole results in a positive D, while a negative dipole leads to a negative D. Consequently, the WF increased for 7-AI-NO 2 , while it decreased for 7-AI and 7-AI-OCH 3 , consistent with previous findings. 11,[18][19][20] Additionally, Kelvin probe force microscopy (KPFM) crossvalidated the WF change (Fig. S7, ESI †).…”

“…Notably, the 7-AI-OCH 3 modified device exhibited a higher V bi (1.326 V) compared to the control (1.261 V), 7-AI-NO 2 (1.297 V), and 7-AI (1.318 V), indicating suppressed nonradiative recombination and a higher V oc output. 20…”

“…A positive dipole results in a positive Δ, while a negative dipole leads to a negative Δ. Consequently, the WF increased for 7-AI-NO 2 , while it decreased for 7-AI and 7-AI-OCH 3 , consistent with previous findings. 11,18–20…”