Interfacial Layer Materials with a Truxene Core for Dopant‐Free NiO_x‐Based Inverted Perovskite Solar Cells

Abstract

Nickel oxide (NiOx) is commonly used as a holetransporting material (HTM) in p‐i‐n perovskite solar cells. However, the weak chemical interaction between the NiOx and CH3NH3PbI3 (MAPbI3) interface results in poor crystallinity, ineffective hole extraction, and enhanced carrier recombination, which are the leading causes for the limited stability and power conversion efficiency (PCE). Herein, two HTMs, TRUX‐D1 (N2,N7,N12‐tris(9,9‐dimethyl‐9H‐fluoren‐2‐yl)‐5,5,10,10,15,15‐hexaheptyl‐N2,N7,N12‐tris(4‐methoxyphenyl)‐10,15‐dihydro‐5H‐diindeno[1,2‐a:1′,2′‐c]fluorene‐2,7,12‐triamine) and TRUX‐D2 (5,5,10,10,15,15‐hexaheptyl‐N2,N7,N12‐tris(4‐methoxyphenyl)‐N2,N7,N12‐tris(10‐methyl‐10H‐phenothiazin‐3‐yl)‐10,15‐dihydro‐5H‐diindeno[1,2‐a:1′,2′‐c]fluorene‐2,7,12‐triamine), are designed with a rigid planar C3 symmetry truxene core integrated with electron‐donating amino groups at peripheral positions. The TRUX‐D molecules are employed as effective interfacial layer (IFL) materials between the NiOx and MAPbI3 interface. The incorporation of truxene‐based IFLs improves the quality of perovskite crystallinity, minimizes nonradiative recombination, and accelerates charge extraction which has been confirmed by various characterization techniques. As a result, the TRUX‐D1 exhibits a maximum PCE of up to 20.8% with an impressive long‐term stability. The unencapsulated device retains 98% of their initial performance following 210 days of aging in a glove box and 75.5% for the device after 80 days under ambient air condition with humidity over 40% at 25 °C.

Exploring the Charge-Transport and Optical Characteristics of Organic Doublet Radicals: A Theoretical and Experimental Study with Photovoltaic Applications

“…49 As shown in Figure S13a and b, the VB level of HSL was reduced from −5.84 to −5.42 eV for 2PACz and 2PACz/radical 2, respectively. The upshift of 420 meV of the VB level indicates the modification of the surface chemical state by radical 2 and provides an additional driving force for hole extraction, 50 resulting in an improved V OC .…”