Molecular Engineering in Hole Transport π‐Conjugated Polymers to Enable High Efficiency Colloidal Quantum Dot Solar Cells

• Published in: Advanced energy materials Vol. 10; no. 8
• Main Authors: Mubarok, Muhibullah Al, Aqoma, Havid, Wibowo, Febrian Tri Adhi, Lee, Wooseop, Kim, Hyung Min, Ryu, Du Yeol, Jeon, Ju‐Won, Jang, Sung‐Yeon
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-02-2020
• Subjects: charge extraction; colloidal quantum dots; Colloiding; Energy conversion efficiency; Exchanging; hole transport layers; Ligands; Optoelectronics; Photovoltaic cells; Quantum dots; Solar cells; Storage stability; Transport; π‐conjugated polymers
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201902933

Organic p‐type materials are potential candidates as solution processable hole transport materials (HTMs) for colloidal quantum dot solar cells (CQDSCs) because of their good hole accepting/electron blocking characteristics and synthetic versatility. However, organic HTMs have still demonstrated inferior performance compared to conventional p‐type CQD HTMs. In this work, organic π‐conjugated polymer (π‐CP) based HTMs, which can achieve performance superior to that of state‐of‐the‐art HTM, p‐type CQDs, are developed. The molecular engineering of the π‐CPs alters their optoelectronic properties, and the charge generation and collection in CQDSCs using them are substantially improved. A device using PBDTTPD‐HT achieves power conversion efficiency (PCE) of 11.53% with decent air‐storage stability. This is the highest reported PCE among CQDSCs using organic HTMs, and even higher than the reported best solid‐state ligand exchange‐free CQDSC using pCQD‐HTM. From the viewpoint of device processing, device fabrication does not require any solid‐state ligand exchange step or layer‐by‐layer deposition process, which is favorable for exploiting commercial processing techniques.
The efficiency of colloidal quantum dot solar cells (CQDSCs) is improved by employing molecularly engineered π‐conjugated polymer‐based organic hole transport materials (HTMs). Their optical and charge generation/collection properties are optimized, and the CQDSC with an efficiency of 11.53%, which is the best among CQDSCs using organic HTMs, is achieved.