Dynamics of interfacial charge transfer between CsPbBr3 perovskite nanocrystals and molecular acceptors for photodetection application

Perovskite nanocrystals (NCs) recently emerged as a suitable candidate for optoelectronic applications because of its simplistic synthesis approach and superior optical properties. For better device performance, the effective absorption of incident photons and the understanding of charge transfer (CT) process are the basic requirements. Herein, we investigate the interfacial charge transfer dynamics of CsPbBr₃NCs in the presence of different molecular acceptors; 7,7,8,8-Tetracyanoquinodimethane (TCNQ) and 11,11,12,12 tetracyanonaphtho-2,6-quinodimethane (TCNAQ). The vivid change in CT dynamics at the interfaces of NCs and two different molecular acceptors (TCNQ and TCNAQ) has been observed. The results demonstrate that the ground state complex formation in the presence of TCNQ acts as additional driving force to accelerate the charge transfer between the NCs and molecular acceptor. Moreover, this donor (NCs)-acceptor (TCNQ, TCNAQ) system results in the higher absorption of incident photons. Finally, the photo detector based on CsPbBr₃-TCNQ system was fabricated for the first time. The device exhibited a high on-off ratio (10⁴). Furthermore, the CsPbBr₃-TCNQ photodetector shows a fast photoresponse times of 180 ms/110 ms (rise/decay time) with a specific detectivity (D*) of 5.2 × 10¹¹Jones. The simple synthesis and outstanding photodetection abilities of this perovskite NCs-molecular acceptor system make them potential candidates for optoelectronic applications.