High-efficiency solid-state-ligand-exchange (SSE) step-free colloidal quantum dot photovoltaic (CQDPV) devices are developed by employing CQD ink based active layers and organic (Polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) and poly(3-hexylthiophene) (P3HT)) based hole transport layers (HTLs). The device using PTB7 as an HTL exhibits superior performance to that using the current leading organic HTL, P3HT, because of favorable energy levels, higher hole mobility, and facilitated interfacial charge transfer. The PTB7 based device achieves power conversion efficiency (PCE) of 9.60%, which is the highest among reported CQDPVs using organic HTLs. This result is also comparable to the PCE of an optimized device based on a thiol-exchanged p-type CQD, the current-state-of-the-art HTL. From the viewpoint of device processing, the fabrication of CQDPVs is achieved by direct single-coating of CQD active layers and organic HTLs at low temperature without SSE steps. The experimental results and device simulation results in this work suggest that further engineering of organic HTL materials can open new doors to improve the performance and processing of CQDPVs.
Bibliographical noteFunding Information:
The authors gratefully acknowledge support from the National Research Foundation (NRF) Grant funded by the Korean Government (MSIP, Grant Nos. 2016R1A5A1012966, 2017M2A2A6A01020854, and 2017R1A2B2009178) and Global Scholarship Program for Foreign Graduate Students at Kookmin University in Korea.
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- charge extraction
- colloidal quantum dots
- hole transport layer
- solar cells
- solid state ligand exchange
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)