A team of researchers led by Prof. Jae Won Shim from the School of Electrical Engineering, Korea Univ (first author Tae Hyuk Kim) and Prof. JaeHong Park from the Department of Chemistry and Nanoscience, Ewha Womans Univ has developed key technologies to maximize the efficiency and stability of advanced indoor organic photovoltaic (OPVs).

Indoor OPVs are emerging as the next-generation technologies for wireless sensors and low-power electronic devices in the Internet of Things (IoT). However, practicality in terms of power supply cannot be guaranteed and significant improvements in power conversion efficiency (PCE) and lifespan are necessary.

Charge carrier dynamics of the 2PACz-mixed photoactive layer are systematically investigated to develop efficient indoor OPVs. Spontaneous vertical phase separation of photoreactive layers with 2PACz forms a vertical component distribution and dramatically improves carrier yield-mobility product which yields suppression of trap-assisted recombination and leaking current in the indoor OPVs. Also, 2PACz-treated ITO leads to induce a sufficiently large work function owing to a vacuum-level shift, thereby enabling efficient energy-level matching to achieve charge selection enhancement at the hole-selective interface.

The champion OPV (~ 36% PCE under indoor lights) system maintains 95 % of its initial efficiency after 1000 h of operation in ambient air. Our findings highlight the tremendous potential of indoor OPVs for simultaneously achieving high efficiency and ambient shelf-lifetime.

Figure 1. illustrates an indoor organic photovoltaics controlled through a system that utilizes a self-assembled monolayer (SAM). (a) current-voltage (J-V) curves of indoor OPVs due to improved charge transfer yield and energy level alignment by combining 2PACz-treated ITO with 2PACz-mixed photoactive layer, (b) energy level schematic diagram of the device, (c) stability of the device.

[Reference] Kim, T. H., Park, N. W., Saeed, M. A., Jeong, S. Y., Woo, H. Y., Park, J., & Shim, J. W. (2023). Record Indoor Performance of Organic Photovoltaics with Long-Term Stability Enabled by Self-Assembled Monolayer-Based Interface Management. Nano Energy, 108429.

[Main Author] Prof. Jae Won Shim (School of Electrical Engineering, Korea University), Prof. JaeHong Park (Department of Chemistry and Nanoscience, Ewha Womans University), Tae Hyuk Kim (School of Electrical Engineering, Korea University)

* Contact : jwshim19@korea.ac.kr, jaehong@ewha.ac.kr