Wen-Kai Lin

Efficiency enhancement of solution-processed inverted organic solar cells with a carbon-nanotube-doped active layer

Solution-processed titanium-doped ZnO (TZO) is synthesized by the sol–gel method to be the electron-transporting layer (ETL) in an inverted organic solar cell (IOSC). Carbon nanotubes (CNTs) are doped into an active layer of poly(3-hexylthiophene):[6,6]-phenyl C 61 butyric acid methyl ester (P3HT:PCBM). The addition of CNTs in the P3HT:PCBM composite increases the conjugation length of P3HT:PCBM:CNTs, which simultaneously enhances the capacity of the composite to absorb solar energy radiation. Vanadium oxide (V2O5) was spin-coated onto the active layer to be a hole-transporting layer (HTL). The power conversion efficiency (PCE) results indicate that the V2O5 nanobelt structure possesses better phase separation and provides a more efficient surface area for the P3HT:PCBM:CNT active layer to increase photocurrent. The optimized IOSCs exhibited an open circuit voltage (Voc), a short-circuit current density (Jsc), a fill factor (FF), and a PCE of 0.55 V, 6.50 mA/cm2, 58.34%, and 2.20%, respectively, under simulated AM1.5G illumination of 100 mW/cm2.

All-solution-processed inverted organic solar cell with a stacked hole-transporting layer

In this study, inverted organic solar cells (IOSCs) have been fabricated and characterized. A sol–gel zinc oxide (ZnO) film is used as a hole-blocking layer (HBL). Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and copper phthalocyanine (CuPc) are used as a hole-transporting layer (HTL). The HBL, active layer, and HTL films are fabricated by spin-coating technique. The anode is fabricated from Ag nanoparticles by drop titration using a Pasteur burette. Experimental results show that the PEDOT:PSS/CuPc stacked HTL provides a stepwise hole-transporting energy diagram configuration, which subsequently increases the charge carrier transporting capability and extracts holes from the active layer to the anode. The characteristics of the IOSCs were optimized and exhibited an open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) of 0.53 V, 6.13 mA/cm2, 37.53%, and 1.24%, respectively, under simulated AM1.5G illumination of 100 mW/cm2. Hence, a solution process is feasible for fabricating low-cost and large-area solar energy devices.

Application of Inorganic/Organic Stacked Hole Transporting Layer in Organic Solar Cells

The high fill factor (FF) and high power conversion efficiency (PCE) of organic solar cells (OSCs) were investigated using an inorganic/organic stacked hole-transporting layer (HTL) of vanadium oxide (V2O5)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) between indium–tin oxide (ITO) and an active layer. The OSC configuration comprises ITO/V2O5/PEDOT:PSS/poly(3-hexylthiophene):phenyl C61-butyric acid methylester (P3HT:PCBM)/LiF/Al. The FF and PCE are 44 and 2.67% under simulated AM1.5G illumination of 100 mW/cm2, which are approximately double and tenfold, respectively, greater than those of a conventional device without the buffer layer. The V2O5/PEDOT:PSS stacked HTL provides a smooth film surface for coating the P3HT:PCBM active layer, in addition to its stepwise hole-transporting configuration, subsequently increasing charge carrier transporting capability and extracting holes from the active layer.

Efficiency enhancement of perovskite solar cells with a buffer layer

The perovskite solar cell using solvent treatment on active layer and a thin buffer layer added was fabricated and characterized. The morphology of MAPM3 active layer agglomerates owing to methylbenzene treatment and the perovskite solar cell shows an increased short circuit current density (Jsc). An efficient buffer layer, the 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi), which enhances device performance by forming well interfacial contact and restraining the hole from transporting to the cathode. The optimized perovskite solar cell showed an open circuit voltage (Voc) of 0.90 V, Jsc of 13.44 mA/cm2, fill factor (F.F.) of 64.69%, and power conversion efficiency (PCE) of 7.81% under simulated AM1.5G illumination of 100 mW/cm2, respectively.

Power efficiency enhancement in solution-processed inverted organic solar cells

Inverted organic solar cells (IOSCs) have been fabricated and characterized. The blend of poly(3-hexythiophene)(P3HT) and [6,6]-phenyl C61-butyric acid methyl ester(PCBM) is adopted as an active material. The anode is formed by Ag nanoparticles, which is fabricated using a Pasteur burette to drop by the titration. The solution-processed cooper phthalocyanine (CuPc) is used as a hole transporting layer (HTL) onto the poly (3,4ethylenedioxythiophene) : poly (sterene sulfonate) (PEDOT:PSS) for realizing to fabricate IOSCs by an all-solution process. An IOSC under the optimized structure of ITO/ZnO/P3HT:PCBM/PEDOT:PSS/CuPc/Ag exhibits open circuit voltage (Voc) of 0.557 V, short circuit current density (Jsc) of 6.344 mA/cm2F.F. of 41.53% and PCE of 1.47% at AM 1.5G of 100 mW/cm2. Solution process is feasible for low-cost, large-area solar energy applications.

Enhancing the efficiency of inverted organic solar cells by using the exciton blocking layers

In this study, inverted organic solar cells (IOSCs) have been fabricated and characterized. Devices structure consists of the blend of poly(3-hexythiophene)(P3HT) and [6,6]-phenyl C61-butyric acid methyl ester(PCBM) as an active layer and a solution process of ZnO and V2O5 as a hole blocking layer (HBL) and electron blocking layer (EBL), respectively. The blocking layer possesses high charge mobility and wide band gap. The wide band gap can effectively suppress the diffusion of electron and hole separating from exciton to the electrodes, reducing the combined effect. Experimental results reveal that ZnO annealed in high temperature to procure nano-ridge can effectively enhance electrons to transport from active layer to the cathode.

Enhancing the efficiency of inverted organic solar cells by employing solution processed blocking layers

Inverted organic solar cells (IOSCs) employing solution-processed blocking layers have been fabricated and characterized. A sol-gel-derived aluminum doped zinc oxide (AZO) film is used as a hole blocking layer (HBL) and a solvent-dissolved nickel oxide (NiO) is an electron blocking layer (EBL). The effects of blocking layer on the opto-electronic characteristics of IOSCs are investigated. The IOSC configuration has been optimized to be ITO/AZO/poly(3-hexylthiophene) (P3HT):phenyl C61-butyric acid methylester (PCBM)/NiO/Ag. It demonstrates a current density (JSC) and a power conversion efficiency (PCE) of 9.25 mA/cm2 and 2.04%, while an OSC without the blocking layers has PCE of 0.56%.