MAPbI3 Perovskite Solar Cells Research Articles

Mesoscopic perovskite solar cells with an admixture of nanocrystalline TiO₂ and Al₂O₃: role of interconnectivity of TiO₂ in charge collection.

Perovskite solar cells with high power conversion efficiency usually employ mesoporous TiO2, however the role of the TiO2 layer has not been clearly resolved. Here we prepared MAPbI3 (MA = CH3NH3) perovskite solar cells with an admixture of nanocrystalline TiO2 and Al2O3 to investigate the role of the mesoporous TiO2 layer. The Al2O3 content was varied from 0% (pure TiO2) to 100% (pure Al2O3) with nominal composition of (1 - x)TiO2 + xAl2O3 (x = 0, 0.25, 0.5, 0.75 and 1). The photocurrent density and fill factor decreased as Al2O3 content increased, whereas the open-circuit voltage was hardly changed. Steady-state photoluminescence (PL) was less quenched as the Al2O3 content increased due to its non-electron-injecting characteristics, where a decrease in PL intensity with increasing TiO2 content was correlated to an increase in photocurrent. Electron injection to TiO2 was also evidenced by time-resolved PL and time-limited photocurrent measurements, where interconnection of TiO2 particles played an important role in charge collection. The slight change in voltage with Al2O3 content was explained by balancing the Fermi position due to a trade-off between charge recombination and the Fermi level. The results observed from the admixture mesoporous layer comprising electron-injecting and electron-non-injecting oxides suggest that electron-injection characteristics play an important role in determining photovoltaic parameters.

Controlled growth of organic–inorganic hybrid CH3NH3PbI3 perovskite thin films from phase-controlled crystalline powders

High-performance MAPbI3 perovskite solar cells with 16% efficiency are fabricated from phase-controlled crystalline powders.

Control of I-V hysteresis in CH3NH3PbI3 perovskite solar cell.

PSS, NiO, and PCBM, which underlines the spiro-MeOTAD in part contributes to the hysteresis. This work is expected to provide a key to the solution of the problem on I-V hysteresis in perovskite solar cell.

CH3NH3PbI3/poly-3-hexylthiophen perovskite mesoscopic solar cells: Performance enhancement by Li-assisted hole conduction

To address if the non-triphenylamine derivative hole transporting materials such as P3HT (poly-3-hexylthiophene) could also exhibit high device efficiency in mesoscopic MAPbI3 perovskite solar cells, we examined the effect of Li-TFSI (Li-bis(trifluoromethanesulfonyl) imide) and t-BP (4-tert-butylpyridine) additives added in P3HT on device performance. Unlike the triphenylamine HTMs, the P3HT thiophene HTM without amine moiety was not doped by the additives but its conductivity was significantly improved by the Li-TFSI/t-BP mediated additional hole conduction. By inclusion of Li-TFSI/t-BP additive, we could fabricate more efficient mesoscopic MAPbI3 perovskite solar cells with smaller hysteresis with respect to scan direction due to Li mediated additional hole conduction. (© 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)