Solution-processed solar-charging power units made of organic photovoltaic modules and asymmetric super-capacitors

Organic photovoltaics with the properties of flexibility, portability, and printability are ideal candidates for low-power-consumption electronics such as the Internet of Things under indoor light conditions. In this work, an all solution-processed integrated photocapacitor (IPC) consisting of an organic photovoltaic module (OPVM) and an asymmetric super-capacitor (ASC) is demonstrated. The OPVM poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene)-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)benzo[1, 2-c:4,5-c′]dithiophene-4,8-dione)] (PBDB-T) : 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone)-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′d′]-s-indaceno[1,2-b:5,6-b-]-dithiophene (ITIC) with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the top electrode delivers a high power conversion efficiency of 6.7% with a voltage of 4.3 V (1 Sun). The ASC based on PEDOT:PSS and Ti3C2Tx electrodes shows a wide operation window of 1.5 V in the aqueous electrolyte with a high energy density of 28.7 μW h cm−2. Consequently, the IPC achieves a high output voltage of 3 V and outstanding overall efficiency of 6.0% (45 000 lx), which shows excellent stability as the solar-charging power unit under room light (500 lx). Synergizing energy harvest and storage in a solution-processed robust, lightweight, low-cost organic IPC enables this solar-charging power unit wide potential applications in low-power-consumption portable electronics.