The photovoltaic response of six cells with an active layer of heterocyclic azo dyes is presented for the first time. The active azo layers differed in the type of substituent (i.e. electron-donating: CH3, OCH3 and electron withdrawing: Br). We showed that by changing the substituent in the heterocyclic azo dye we change the power efficiency of the device. It should be mentioned that all presented data showed high potential of heterocyclic azo dyes for effective photovoltaic output. The studied heterocyclic azo dyes have higher photovoltaic parameters than those obtained for photovoltaic cell with 4-Diethoxyphenylsilylazobenzene.