Abstract
An in-depth study on the photovoltaic characteristics under indoor lights, i.e., light-emitting diode (LED), fluorescent lamps, and halogen lamps, was performed with varying the photoactive layer thickness (120–870 nm), by comparing those under 1-sun condition. The semi-crystalline mid-gap photoactive polymer, poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2FBT) and a fullerene derivative, [6,6]-phenyl C 71 butyric acid methyl ester (PC 70 BM) were used as a photoactive layer. In the contrary to the measurements under 1-sun condition, the indoor devices show a clearly different behavior, showing the thickness tolerant short-circuit current density (J SC ) and fill factor (FF) values with 280–870 nm thick photoactive layers. The retained J SC and FF values of thick indoor devices were discussed in terms of the parasitic resistance effects based on the single-diode equivalent circuit model. The much lower series/shunt resistance (Rs/R P ) ratio was measured with thick photoactive layer (≥280 nm), resulting in negligible decreases in the J SC and FF values even with a 870-nm-thick active layer under the LED condition. Under 1000 lx LED light, the PPDT2FBT:PC 70 BM device showed an optimum power conversion efficiency (PCE) of 16% (max power density, 44.8 μW/cm 2 ) with an open-circuit voltage of 587 mV, a J SC of 117 μA/cm 2 , and a FF of 65.2. The device with a 870-nm-thick active layer still exhibited an excellent performance with a PCE of 12.5%. These results clearly suggest that the critical parasitic resistance effects on the performance vary depending on the light illumination condition, and the large R P associated with the viable thick photoactive layer and the well-matched absorption (of photoactive layer) with the irradiance spectrum (of indoor light) are essential to realize efficient indoor photovoltaic cells with high J SC and FF.
Original language | English |
---|---|
Pages (from-to) | 466-475 |
Number of pages | 10 |
Journal | Nano Energy |
Volume | 58 |
DOIs | |
Publication status | Published - 2019 Apr 1 |
Keywords
- Indoor light conditions
- Organic photovoltaics
- Poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2, 5]thiadiazole)]
- Semi-crystalline polymer
- Single-diode equivalent circuit model
- Ultra-thick photoactive layer
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)
- Electrical and Electronic Engineering