Re ECF Project: ECF 2015-33

Project Title: Novel fully solution-processed low-cost and stable solar cells promoting the use of low-carbon energy

Applicant: Professor CHOY Chik Ho Wallace, Department of Electrical and Electronic Engineering, The University of Hong Kong

Total Approved Grant: $499,054 (ECF & WWGF: 50/50)

Duration: 1/9/2016 to 28/2/2018

Project Status/Remarks: Completed

The project aims to :

(a). propose a new approach to realize all-solution-processed solar cells with the features of simple solution-based, low temperature (<100degC) and room atmosphere fabrication (i.e. scalable, low cost, no need of expensive, high energy- and carbon- consumed vacuum processes) for promoting low-carbon energy and enhancing the energy efficiency; and
(b). demonstrate the operation and working mechanisms of the all-solution-processed solar cells for encouraging the knowledge building of the low-carbon energy to public and advanced knowledge / technology exchange in the field / industry.

Summary of the Findings/Outcomes:
The research team has successfully demonstrated all-solution-processed solar cells fabricated using only low-cost and simple process (i.e. fully solution-processed, room atmosphere and low-temperature condition) with power conversion efficiency over 17 on ITO substrate and good device stability and lifetime. They have developed various flexible electrode, inorganic based carrier transport layer and perovskite based active layer all in low-temperature solution processes and low temperature (< 100degC). The flexible electrode has good electrical properties and optical transparency simultaneously. The carrier transport layer has good energy band alignment with the active layer and electrode for efficient carrier extraction. Remarkably, with the research team’s new approach of perovskite active layer, the devices show the best photovoltaic performance with PCE of 17.10% on rigid substrate; and negligible hysteresis and maintain stable performance during 1,000h exposure to ambient environment. In addition, the room-temperature solution-processed technique enables the fabrication of lightweight flexible PVSCs with high PCE of 14.19% and remarkable power-per-weight of 24 W/g. The work not only proves the feasibility of producing highly efficient PVSCs enabled by all room-temperature solution processing techniques, but also opens a new avenue to realize the large-scale production of low-cost perovskite-based photovoltaics. Findings of the project were disseminated through the publication of a journal, sharing with different companies and teaching in the MSc and PhD courses of The University of Hong Kong.